1
|
Amiri P, Casals O, Daniel Prades J, Hartmann J, Waag A, Pannek C, Engel L, Auf der Maur M. Monolithic integrated light-emitting-diode/photodetector sensor for photoactive analyte monitoring: design and simulation. Appl Opt 2024; 63:853-860. [PMID: 38294401 DOI: 10.1364/ao.510685] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2023] [Accepted: 12/26/2023] [Indexed: 02/01/2024]
Abstract
We present the simulation and design optimization of an integrated light-emitting-diode/photodetector (LED-PD) sensor system for monitoring of light absorbance changes developing in analyte-sensitive compounds. The sensor integrates monolithically both components in a single chip, offering advantages such as downsizing, reduced assembly complexity, and lower power consumption. The changes in the optical parameters of the analyte-sensitive ink are detected by monitoring the power transmission from the LED to the PD. Ray tracing and coupled modeling approach (CMA) simulations are employed to investigate the interaction of the emitted light with the ink. In highly absorbing media, CMA predicts more accurate results by considering evanescent waves. Simulations also suggest that an approximately 39% change in optical transmission can be achieved by adjusting the ink-deposited layer thickness and varying the extinction coefficient from 10-4 to 3×10-4.
Collapse
|
2
|
Di Vito A, Amiri P, Bornemann S, Schöttler G, Vergin M, Meierhofer F, Gülink J, Waag A, Canals J, Diéguez A, Prades JD, Auf der Maur M. Design study of a micro illumination platform based on GaN microLED arrays. Appl Opt 2023; 62:7503-7511. [PMID: 37855520 DOI: 10.1364/ao.498432] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/23/2023] [Accepted: 09/06/2023] [Indexed: 10/20/2023]
Abstract
The design study of a micro illumination tool based on GaN microLED arrays is presented. The high spatio-temporal resolution and the capability of generating fully customized optical patterns that characterize the proposed platform would enable the manipulation of biological systems, e.g., for optogenetics applications. Based on ray tracing simulations, the design aspects that mainly affect the device performance have been identified, and the related structural parameters have been optimized to improve the extraction efficiency and the spatial resolution of the resulting light patterns. Assuming that the device is a bottom emitter, and the light is extracted from the n-side, the presence of mesa-structures on the p-side of the GaN layer can affect both the efficiency and the resolution, being optimized for different values of the mesa-side inclination angle. The full width at half maximum (FWHM) of the extracted spots is mainly determined by the substrate thickness, and the relation between the FWHM and the array pitch represents a criterion to define the resolution. Namely, when F W H M
Collapse
|
3
|
Barettin D, Sakharov AV, Tsatsulnikov AF, Nikolaev AE, Pecchia A, Auf der Maur M, Karpov SY, Cherkashin N. Impact of Local Composition on the Emission Spectra of InGaN Quantum-Dot LEDs. Nanomaterials (Basel) 2023; 13:1367. [PMID: 37110952 PMCID: PMC10145816 DOI: 10.3390/nano13081367] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/24/2023] [Revised: 04/07/2023] [Accepted: 04/12/2023] [Indexed: 06/19/2023]
Abstract
A possible solution for the realization of high-efficiency visible light-emitting diodes (LEDs) exploits InGaN-quantum-dot-based active regions. However, the role of local composition fluctuations inside the quantum dots and their effect of the device characteristics have not yet been examined in sufficient detail. Here, we present numerical simulations of a quantum-dot structure restored from an experimental high-resolution transmission electron microscopy image. A single InGaN island with the size of ten nanometers and nonuniform indium content distribution is analyzed. A number of two- and three-dimensional models of the quantum dot are derived from the experimental image by a special numerical algorithm, which enables electromechanical, continuum k→·p→, and empirical tight-binding calculations, including emission spectra prediction. Effectiveness of continuous and atomistic approaches are compared, and the impact of InGaN composition fluctuations on the ground-state electron and hole wave functions and quantum dot emission spectrum is analyzed in detail. Finally, comparison of the predicted spectrum with the experimental one is performed to assess the applicability of various simulation approaches.
Collapse
Affiliation(s)
- Daniele Barettin
- Department of Electronic Engineering, Università Niccoló Cusano, 00133 Rome, Italy
| | - Alexei V. Sakharov
- Ioffe Physico-Technical Institute RAS, 26 Polytekhnicheskaya str., 194021 St. Petersburg, Russia; (A.V.S.); (A.F.T.); (A.E.N.)
| | - Andrey F. Tsatsulnikov
- Ioffe Physico-Technical Institute RAS, 26 Polytekhnicheskaya str., 194021 St. Petersburg, Russia; (A.V.S.); (A.F.T.); (A.E.N.)
| | - Andrey E. Nikolaev
- Ioffe Physico-Technical Institute RAS, 26 Polytekhnicheskaya str., 194021 St. Petersburg, Russia; (A.V.S.); (A.F.T.); (A.E.N.)
| | | | - Matthias Auf der Maur
- Department of Electronic Engineering, University of Rome Tor Vergata, Via del Politecnico 1, 00133 Rome, Italy
| | - Sergey Yu. Karpov
- Soft-Impact, Ltd., P.O. Box 83, 27 Engels ave., 194156 St. Petersburg, Russia
| | - Nikolay Cherkashin
- CEMES-CNRS and Université de Toulouse, 29 rue Jeanne Marvig, BP 94347, F-31055 Toulouse, CEDEX 4, France
| |
Collapse
|
4
|
Ries M, Nippert F, März B, Alonso-Orts M, Grieb T, Hötzel R, Hille P, Emtenani P, Akinoglu EM, Speiser E, Plaickner J, Schörmann J, Auf der Maur M, Müller-Caspary K, Rosenauer A, Esser N, Eickhoff M, Wagner MR. Origin of the spectral red-shift and polarization patterns of self-assembled InGaN nanostructures on GaN nanowires. Nanoscale 2023; 15:7077-7085. [PMID: 36987591 DOI: 10.1039/d2nr05529e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/19/2023]
Abstract
The luminescence of InxGa1-xN nanowires (NWs) is frequently reported with large red-shifts as compared to the theoretical value expected from the average In content. Both compositional fluctuations and radial built-in fields were considered accountable for this effect, depending on the size, structure, composition, and surrounding medium of the NWs. In the present work, the emission properties of InGaN/GaN NWs grown by plasma-assisted molecular beam epitaxy are investigated in a comprehensive study combining ultraviolet-Raman and photoluminescence spectroscopy (PL) on vertical arrays, polarization-dependent PL on bundles of a few NWs, scanning transmission electron microscopy, energy-dispersive X-ray spectroscopy, and calculations of the band profiles. The roles of inhomogeneous In distribution and radial fields in the context of optical emission properties are addressed. The radial built-in fields are found to be modest, with a maximum surface band bending below 350 meV. On the other hand, variations in the local In content have been observed that give rise to potential fluctuations whose impact on the emission properties is shown to prevail over band-bending effects. Two luminescence bands with large positive and moderate negative polarization ratios of ≈+80% and ≤-60%, respectively, were observed. The red-shift in the luminescence is associated with In-rich inclusions in the NWs due to thermodynamic decomposition during growth. The negative polarization anisotropy is suggested to result from spontaneously formed superlattices in the In-rich regions of the NWs. The NWs show a preferred orthogonal absorption due to the dielectric boundary conditions and highlight the extreme sensitivity of these structures towards light polarization.
Collapse
Affiliation(s)
- Maximilian Ries
- Technische Universität Berlin, Institut für Festkörperphysik, Hardenbergstraße 36, 10623 Berlin, Germany.
- Leibniz-Institut für Analytische Wissenschaften - ISAS e.V., Department Interface Analytics, Schwarzschildstraße 8, 12489 Berlin, Germany
| | - Felix Nippert
- Technische Universität Berlin, Institut für Festkörperphysik, Hardenbergstraße 36, 10623 Berlin, Germany.
| | - Benjamin März
- Ernst-Ruska-Centre for Microscopy and Spectroscopy with Electrons at Forschungszentrum Jülich, Wilhelm-Johnen-Str., 52425 Jülich, Germany
- Department of Chemistry and Center for NanoScience, Ludwig-Maximilians-Universität München, Butenandtstr. 11, 81377 Munich, Germany
| | - Manuel Alonso-Orts
- Universität Bremen, Institut für Festkörperphysik, Otto-Hahn-Allee 1, 28359 Bremen, Germany
| | - Tim Grieb
- Universität Bremen, Institut für Festkörperphysik, Otto-Hahn-Allee 1, 28359 Bremen, Germany
- Universität Bremen, MAPEX Center for Materials and Processes, Bibliothekstr. 1, 28359 Bremen, Germany
| | - Rudolfo Hötzel
- Universität Bremen, Institut für Festkörperphysik, Otto-Hahn-Allee 1, 28359 Bremen, Germany
| | - Pascal Hille
- Universität Bremen, Institut für Festkörperphysik, Otto-Hahn-Allee 1, 28359 Bremen, Germany
| | - Pouria Emtenani
- Technische Universität Berlin, Institut für Festkörperphysik, Hardenbergstraße 36, 10623 Berlin, Germany.
| | - Eser Metin Akinoglu
- Leibniz-Institut für Analytische Wissenschaften - ISAS e.V., Department Interface Analytics, Schwarzschildstraße 8, 12489 Berlin, Germany
| | - Eugen Speiser
- Leibniz-Institut für Analytische Wissenschaften - ISAS e.V., Department Interface Analytics, Schwarzschildstraße 8, 12489 Berlin, Germany
| | - Julian Plaickner
- Leibniz-Institut für Analytische Wissenschaften - ISAS e.V., Department Interface Analytics, Schwarzschildstraße 8, 12489 Berlin, Germany
- Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Hahn-Meitner-Platz 1, 14109 Berlin, Germany
| | - Jörg Schörmann
- Justus-Liebig-Universität Gießen, I. Physikalisches Institut und Zentrum für Materialforschung (LaMa), Heinrich-Buff-Ring 16, 35392 Gießen, Germany
| | - Matthias Auf der Maur
- University of Rome Tor Vergata, Department of Electronic Engineering, Via del Politecnico 1, 00133 Rome, Italy
| | - Knut Müller-Caspary
- Department of Chemistry and Center for NanoScience, Ludwig-Maximilians-Universität München, Butenandtstr. 11, 81377 Munich, Germany
| | - Andreas Rosenauer
- Universität Bremen, Institut für Festkörperphysik, Otto-Hahn-Allee 1, 28359 Bremen, Germany
- Universität Bremen, MAPEX Center for Materials and Processes, Bibliothekstr. 1, 28359 Bremen, Germany
| | - Norbert Esser
- Technische Universität Berlin, Institut für Festkörperphysik, Hardenbergstraße 36, 10623 Berlin, Germany.
- Leibniz-Institut für Analytische Wissenschaften - ISAS e.V., Department Interface Analytics, Schwarzschildstraße 8, 12489 Berlin, Germany
| | - Martin Eickhoff
- Universität Bremen, Institut für Festkörperphysik, Otto-Hahn-Allee 1, 28359 Bremen, Germany
| | - Markus R Wagner
- Technische Universität Berlin, Institut für Festkörperphysik, Hardenbergstraße 36, 10623 Berlin, Germany.
- Paul-Drude-Institut für Festkörperelektronik, Leibniz-Institut im Forschungsverbund Berlin e.V., Hausvogteiplatz 5-7, 10117 Berlin, Germany
| |
Collapse
|
5
|
Alonso-Orts M, Hötzel R, Grieb T, Auf der Maur M, Ries M, Nippert F, März B, Müller-Caspary K, Wagner MR, Rosenauer A, Eickhoff M. Correlative analysis on InGaN/GaN nanowires: structural and optical properties of self-assembled short-period superlattices. Nanoscale Res Lett 2023; 18:27. [PMID: 36856901 DOI: 10.1186/s11671-023-03808-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/10/2023] [Accepted: 02/20/2023] [Indexed: 05/24/2023]
Abstract
The influence of self-assembled short-period superlattices (SPSLs) on the structural and optical properties of InGaN/GaN nanowires (NWs) grown by PAMBE on Si (111) was investigated by STEM, EDXS, µ-PL analysis and k·p simulations. STEM analysis on single NWs indicates that in most of the studied nanostructures, SPSLs self-assemble during growth. The SPSLs display short-range ordering of In-rich and In-poor InxGa1-xN regions with a period of 2-3 nm that are covered by a GaN shell and that transition to a more homogenous InxGa1-xN core. Polarization- and temperature-resolved PL analysis performed on the same NWs shows that they exhibit a strong parallel polarized red-yellow emission and a predominantly perpendicular polarized blue emission, which are ascribed to different In-rich regions in the nanostructures. The correlation between STEM, µ-PL and k·p simulations provides better understanding of the rich optical emission of complex III-N nanostructures and how they are impacted by structural properties, yielding the significant impact of strain on self-assembly and spectral emission.
Collapse
Affiliation(s)
- Manuel Alonso-Orts
- Institut für Festkörperphysik, Universität Bremen, Otto-Hahn-Allee, 28359, Bremen, Germany.
| | - Rudolfo Hötzel
- Institut für Festkörperphysik, Universität Bremen, Otto-Hahn-Allee, 28359, Bremen, Germany
| | - Tim Grieb
- Institut für Festkörperphysik, Universität Bremen, Otto-Hahn-Allee, 28359, Bremen, Germany
| | - Matthias Auf der Maur
- Department of Electronic Engineering, University of Rome Tor Vergata, Via del Politecnico 1, 00133, Rome, Italy
| | - Maximilian Ries
- Institut für Festkörperphysik, Technische Universität Berlin, Hardenbergstraße 36, 10623, Berlin, Germany
| | - Felix Nippert
- Institut für Festkörperphysik, Technische Universität Berlin, Hardenbergstraße 36, 10623, Berlin, Germany
| | - Benjamin März
- Department of Chemistry and Centre for NanoScience, Ludwig-Maximilians-Universität Munich, Butenandtstr. 11, 81377, Munich, Germany
| | - Knut Müller-Caspary
- Department of Chemistry and Centre for NanoScience, Ludwig-Maximilians-Universität Munich, Butenandtstr. 11, 81377, Munich, Germany
| | - Markus R Wagner
- Institut für Festkörperphysik, Technische Universität Berlin, Hardenbergstraße 36, 10623, Berlin, Germany
- Paul-Drude-Institut für Festkörperelektronik, Leibniz-Institut im Forschungsverbund Berlin e.V., 10117, Berlin, Germany
| | - Andreas Rosenauer
- Institut für Festkörperphysik, Universität Bremen, Otto-Hahn-Allee, 28359, Bremen, Germany
| | - Martin Eickhoff
- Institut für Festkörperphysik, Universität Bremen, Otto-Hahn-Allee, 28359, Bremen, Germany
| |
Collapse
|
6
|
Abstract
Wurtzite AlGaAs is a technologically promising yet unexplored material. Here we study it both experimentally and numerically. We develop a complete numerical model based on an 8-band k→·p→ method, including electromechanical fields, and calculate the optoelectronic properties of wurtzite AlGaAs nanowires with different Al content. We then compare them with our experimental data. Our results strongly suggest that wurtzite AlGaAs is a direct band gap material. Moreover, we have also numerically obtained the band gap of wurtzite AlAs and the valence band offset between AlAs and GaAs in the wurtzite symmetry.
Collapse
Affiliation(s)
- Daniele Barettin
- Department of Electronic Engineering, Università degli Studi Niccolò Cusano - Telematica, via don Carlo Gnocchi 3, Rome00166, Italy
| | - Igor V Shtrom
- St. Petersburg State University, Saint Petersburg199034, Russian Federation
- Alferov University, Saint Petersburg194021, Russian Federation
- Institute for Analytical Instrumentation, Russian Academy of Sciences, Saint Petersburg190103, Russian Federation
| | - Rodion R Reznik
- St. Petersburg State University, Saint Petersburg199034, Russian Federation
| | - Sergey V Mikushev
- St. Petersburg State University, Saint Petersburg199034, Russian Federation
| | - George E Cirlin
- St. Petersburg State University, Saint Petersburg199034, Russian Federation
- Alferov University, Saint Petersburg194021, Russian Federation
- Institute for Analytical Instrumentation, Russian Academy of Sciences, Saint Petersburg190103, Russian Federation
| | - Matthias Auf der Maur
- Department of Electronic Engineering, University of Rome Tor Vergata, Rome00133, Italy
| | - Nika Akopian
- DTU Department of Electrical and Photonics Engineering, Technical University of Denmark, Kgs. Lyngby2800, Denmark
| |
Collapse
|
7
|
Obraztsova AA, Barettin D, Furasova AD, Voroshilov PM, Auf der Maur M, Orsini A, Makarov SV. Light-Trapping Electrode for the Efficiency Enhancement of Bifacial Perovskite Solar Cells. Nanomaterials (Basel) 2022; 12:3210. [PMID: 36144998 PMCID: PMC9500818 DOI: 10.3390/nano12183210] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/04/2022] [Revised: 09/02/2022] [Accepted: 09/08/2022] [Indexed: 06/16/2023]
Abstract
Antireflection and light-trapping coatings are important parts of photovoltaic architectures, which enable the reduction of parasitic optical losses, and therefore increase the power conversion efficiency (PCE). Here, we propose a novel approach to enhance the efficiency of perovskite solar cells using a light-trapping electrode (LTE) with non-reciprocal optical transmission, consisting of a perforated metal film covered with a densely packed array of nanospheres. Our LTE combines charge collection and light trapping, and it can replace classical transparent conducting oxides (TCOs) such as ITO or FTO, providing better optical transmission and conductivity. One of the most promising applications of our original LTE is the optimization of efficient bifacial perovskite solar cells. We demonstrate that with our LTE, the short-circuit current density and fill factor are improved for both front and back illumination of the solar cells. Thus, we observe an 11% improvement in the light absorption for the monofacial PSCs, and a 15% for the bifacial PSCs. The best theoretical results of efficiency for our PSCs are 27.9% (monofacial) and 33.4% (bifacial). Our study opens new prospects for the further efficiency enhancement for perovskite solar cells.
Collapse
Affiliation(s)
- Anna A. Obraztsova
- School of Physics and Engineering, ITMO University, St. Petersburg 197101, Russia
| | - Daniele Barettin
- Department of Electronic Engineering, Università Niccoló Cusano, 00133 Rome, Italy
| | | | - Pavel M. Voroshilov
- School of Physics and Engineering, ITMO University, St. Petersburg 197101, Russia
| | - Matthias Auf der Maur
- Department of Electronic Engineering, University of Rome ‘Tor Vergata’, Via del Politecnico 1, 00133 Rome, Italy
| | - Andrea Orsini
- Department of Electronic Engineering, Università Niccoló Cusano, 00133 Rome, Italy
| | - Sergey V. Makarov
- School of Physics and Engineering, ITMO University, St. Petersburg 197101, Russia
- Harbin Engineering University, Harbin 150001, China
- Qingdao Innovation and Development Center of Harbin Engineering University, Qingdao 266000, China
| |
Collapse
|
8
|
Di Vito A, Pecchia A, Auf der Maur M, Campanari V, Martelli F, Di Carlo A. Role of Phase Nanosegregation in the Photoluminescence Spectra of Halide Perovskites. J Phys Chem Lett 2021; 12:11659-11665. [PMID: 34823362 PMCID: PMC8667165 DOI: 10.1021/acs.jpclett.1c03378] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2021] [Accepted: 11/15/2021] [Indexed: 06/13/2023]
Abstract
The study of MAPbI3 phase transitions based on temperature-dependent optical spectroscopy has recently gained a huge attention. Photoluminescence (PL) investigations of the tetragonal-orthorhombic transition suggest that tetragonal nanodomains are present below the transition temperature and signatures associated with tetragonal segregations are observed. We have studied the impact of phase nanosegregation across the orthorhombic-tetragonal phase transition of MAPbI3 on the system's properties employing a tight binding (TB) approach. The particle swarm optimization has been used to obtain a consistent set of TB parameters, where the target properties of the system have been derived by first-principles calculations. The theoretical results have been compared with the measured PL spectra for a temperature range going from 10 to 100 K. Our model effectively captures the carriers' localization phenomenon induced by the presence of residual tetragonal nanodomains and demonstrates that the assumption of phase nanosegregation can explain the low-energy features in the PL spectra of MAPbI3.
Collapse
Affiliation(s)
- Alessia Di Vito
- University
of Rome “Tor Vergata”, Via del Politecnico 1, 00133, Rome, Italy
| | - Alessandro Pecchia
- CNR-ISMN, Via Salaria km 29,300, 00014 Monterotondo Stazione, Rome, Italy
| | | | - Valerio Campanari
- University
of Rome “Tor Vergata”, Via del Politecnico 1, 00133, Rome, Italy
| | | | - Aldo Di Carlo
- University
of Rome “Tor Vergata”, Via del Politecnico 1, 00133, Rome, Italy
- LASE,
Laboratory of Advanced Solar Energy, National
University of Science and Technology “MISiS”, Leninsky prospect 4, 119049, Moscow, Russia
| |
Collapse
|
9
|
Moreno S, Canals J, Moro V, Franch N, Vilà A, Romano-Rodriguez A, Prades JD, Bezshlyakh DD, Waag A, Kluczyk-Korch K, Auf der Maur M, Di Carlo A, Krieger S, Geleff S, Diéguez A. Pursuing the Diffraction Limit with Nano-LED Scanning Transmission Optical Microscopy. Sensors (Basel) 2021; 21:3305. [PMID: 34064543 PMCID: PMC8151575 DOI: 10.3390/s21103305] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/04/2021] [Revised: 05/04/2021] [Accepted: 05/05/2021] [Indexed: 11/24/2022]
Abstract
Recent research into miniaturized illumination sources has prompted the development of alternative microscopy techniques. Although they are still being explored, emerging nano-light-emitting-diode (nano-LED) technologies show promise in approaching the optical resolution limit in a more feasible manner. This work presents the exploration of their capabilities with two different prototypes. In the first version, a resolution of less than 1 µm was shown thanks to a prototype based on an optically downscaled LED using an LED scanning transmission optical microscopy (STOM) technique. This research demonstrates how this technique can be used to improve STOM images by oversampling the acquisition. The second STOM-based microscope was fabricated with a 200 nm GaN LED. This demonstrates the possibilities for the miniaturization of on-chip-based microscopes.
Collapse
Affiliation(s)
- Sergio Moreno
- Electronic and Biomedical Engineering Department, University of Barcelona, 08028 Barcelona, Spain; (J.C.); (V.M.); (N.F.); (A.V.); (A.R.-R.); (J.D.P.); (A.D.)
| | - Joan Canals
- Electronic and Biomedical Engineering Department, University of Barcelona, 08028 Barcelona, Spain; (J.C.); (V.M.); (N.F.); (A.V.); (A.R.-R.); (J.D.P.); (A.D.)
| | - Victor Moro
- Electronic and Biomedical Engineering Department, University of Barcelona, 08028 Barcelona, Spain; (J.C.); (V.M.); (N.F.); (A.V.); (A.R.-R.); (J.D.P.); (A.D.)
| | - Nil Franch
- Electronic and Biomedical Engineering Department, University of Barcelona, 08028 Barcelona, Spain; (J.C.); (V.M.); (N.F.); (A.V.); (A.R.-R.); (J.D.P.); (A.D.)
| | - Anna Vilà
- Electronic and Biomedical Engineering Department, University of Barcelona, 08028 Barcelona, Spain; (J.C.); (V.M.); (N.F.); (A.V.); (A.R.-R.); (J.D.P.); (A.D.)
- Institute for Nanoscience and Nanotechnology-IN2UB, University of Barcelona, 08028 Barcelona, Spain
| | - Albert Romano-Rodriguez
- Electronic and Biomedical Engineering Department, University of Barcelona, 08028 Barcelona, Spain; (J.C.); (V.M.); (N.F.); (A.V.); (A.R.-R.); (J.D.P.); (A.D.)
- Institute for Nanoscience and Nanotechnology-IN2UB, University of Barcelona, 08028 Barcelona, Spain
| | - Joan Daniel Prades
- Electronic and Biomedical Engineering Department, University of Barcelona, 08028 Barcelona, Spain; (J.C.); (V.M.); (N.F.); (A.V.); (A.R.-R.); (J.D.P.); (A.D.)
- Institute for Nanoscience and Nanotechnology-IN2UB, University of Barcelona, 08028 Barcelona, Spain
| | - Daria D. Bezshlyakh
- Institute of Semiconductor Technology, Technische Universität Braunschweig, 38106 Braunschweig, Germany; (D.D.B.); (A.W.)
| | - Andreas Waag
- Institute of Semiconductor Technology, Technische Universität Braunschweig, 38106 Braunschweig, Germany; (D.D.B.); (A.W.)
| | - Katarzyna Kluczyk-Korch
- Department of Electronic Engineering, University of Rome “Tor Vergara”, 00133 Roma, Italy; (K.K.-K.); (M.A.d.M.); (A.D.C.)
- Faculty of Physics, University of Warsaw, 00-662 Warsaw, Poland
| | - Matthias Auf der Maur
- Department of Electronic Engineering, University of Rome “Tor Vergara”, 00133 Roma, Italy; (K.K.-K.); (M.A.d.M.); (A.D.C.)
| | - Aldo Di Carlo
- Department of Electronic Engineering, University of Rome “Tor Vergara”, 00133 Roma, Italy; (K.K.-K.); (M.A.d.M.); (A.D.C.)
- CNR-ISM, 00128 Rome, Italy
| | - Sigurd Krieger
- Department of Pathology, Medical University of Vienna, 1210 Wien, Austria; (S.K.); (S.G.)
| | - Silvana Geleff
- Department of Pathology, Medical University of Vienna, 1210 Wien, Austria; (S.K.); (S.G.)
| | - Angel Diéguez
- Electronic and Biomedical Engineering Department, University of Barcelona, 08028 Barcelona, Spain; (J.C.); (V.M.); (N.F.); (A.V.); (A.R.-R.); (J.D.P.); (A.D.)
- Institute for Nanoscience and Nanotechnology-IN2UB, University of Barcelona, 08028 Barcelona, Spain
| |
Collapse
|
10
|
Canals J, Franch N, Moro V, Moreno S, Prades JD, Romano-Rodríguez A, Bornemann S, Bezshlyakh DD, Waag A, Vogelbacher F, Schrittwieser S, Kluczyk-Korch K, Auf der Maur M, Di Carlo A, Diéguez A. A Novel Approach for a Chip-Sized Scanning Optical Microscope. Micromachines (Basel) 2021; 12:527. [PMID: 34066638 PMCID: PMC8148435 DOI: 10.3390/mi12050527] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Revised: 04/30/2021] [Accepted: 05/05/2021] [Indexed: 12/28/2022]
Abstract
The recent advances in chip-size microscopy based on optical scanning with spatially resolved nano-illumination light sources are presented. This new straightforward technique takes advantage of the currently achieved miniaturization of LEDs in fully addressable arrays. These nano-LEDs are used to scan the sample with a resolution comparable to the LED sizes, giving rise to chip-sized scanning optical microscopes without mechanical parts or optical accessories. The operation principle and the potential of this new kind of microscope are analyzed through three different implementations of decreasing LED dimensions from 20 µm down to 200 nm.
Collapse
Affiliation(s)
- Joan Canals
- Department of Electronic and Biomedical Engineering, University of Barcelona, 08028 Barcelona, Spain; (N.F.); (V.M.); (S.M.); (J.D.P.); (A.R.-R.); (A.D.)
| | - Nil Franch
- Department of Electronic and Biomedical Engineering, University of Barcelona, 08028 Barcelona, Spain; (N.F.); (V.M.); (S.M.); (J.D.P.); (A.R.-R.); (A.D.)
| | - Victor Moro
- Department of Electronic and Biomedical Engineering, University of Barcelona, 08028 Barcelona, Spain; (N.F.); (V.M.); (S.M.); (J.D.P.); (A.R.-R.); (A.D.)
| | - Sergio Moreno
- Department of Electronic and Biomedical Engineering, University of Barcelona, 08028 Barcelona, Spain; (N.F.); (V.M.); (S.M.); (J.D.P.); (A.R.-R.); (A.D.)
| | - Juan Daniel Prades
- Department of Electronic and Biomedical Engineering, University of Barcelona, 08028 Barcelona, Spain; (N.F.); (V.M.); (S.M.); (J.D.P.); (A.R.-R.); (A.D.)
| | - Albert Romano-Rodríguez
- Department of Electronic and Biomedical Engineering, University of Barcelona, 08028 Barcelona, Spain; (N.F.); (V.M.); (S.M.); (J.D.P.); (A.R.-R.); (A.D.)
| | - Steffen Bornemann
- Institute of Semiconductor Technology, Technische Universität Braunschweig, 38106 Braunschweig, Germany; (S.B.); (D.D.B.); (A.W.)
| | - Daria D. Bezshlyakh
- Institute of Semiconductor Technology, Technische Universität Braunschweig, 38106 Braunschweig, Germany; (S.B.); (D.D.B.); (A.W.)
| | - Andreas Waag
- Institute of Semiconductor Technology, Technische Universität Braunschweig, 38106 Braunschweig, Germany; (S.B.); (D.D.B.); (A.W.)
| | - Florian Vogelbacher
- Molecular Diagnostics, AIT Austrian Institute of Technology, 1210 Vienna, Austria; (F.V.); (S.S.)
| | - Stefan Schrittwieser
- Molecular Diagnostics, AIT Austrian Institute of Technology, 1210 Vienna, Austria; (F.V.); (S.S.)
| | - Katarzyna Kluczyk-Korch
- Dipartimento di Ingegneria Elettronica, University of Rome Tor Vergata, 00133 Rome, Italy; (K.K.-K.); (M.A.d.M.); (A.D.C.)
| | - Matthias Auf der Maur
- Dipartimento di Ingegneria Elettronica, University of Rome Tor Vergata, 00133 Rome, Italy; (K.K.-K.); (M.A.d.M.); (A.D.C.)
| | - Aldo Di Carlo
- Dipartimento di Ingegneria Elettronica, University of Rome Tor Vergata, 00133 Rome, Italy; (K.K.-K.); (M.A.d.M.); (A.D.C.)
| | - Angel Diéguez
- Department of Electronic and Biomedical Engineering, University of Barcelona, 08028 Barcelona, Spain; (N.F.); (V.M.); (S.M.); (J.D.P.); (A.R.-R.); (A.D.)
| |
Collapse
|
11
|
Franch N, Canals J, Moro V, Vilá A, Romano-Rodríguez A, Prades JD, Gülink J, Bezshlyakh D, Waag A, Kluczyk-Korch K, Auf der Maur M, di Carlo A, Diéguez Á. Nano illumination microscopy: a technique based on scanning with an array of individually addressable nanoLEDs. Opt Express 2020; 28:19044-19057. [PMID: 32672190 DOI: 10.1364/oe.391497] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/26/2020] [Accepted: 04/29/2020] [Indexed: 06/11/2023]
Abstract
In lensless microscopy, spatial resolution is usually provided by the pixel density of current digital cameras, which are reaching a hard-to-surpass pixel size / resolution limit over 1 µm. As an alternative, the dependence of the resolving power can be moved from the detector to the light sources, offering a new kind of lensless microscopy setups. The use of continuously scaled-down Light-Emitting Diode (LED) arrays to scan the sample allows resolutions on order of the LED size, giving rise to compact and low-cost microscopes without mechanical scanners or optical accessories. In this paper, we present the operation principle of this new approach to lensless microscopy, with simulations that demonstrate the possibility to use it for super-resolution, as well as a first prototype. This proof-of-concept setup integrates an 8 × 8 array of LEDs, each 5 × 5 μm2 pixel size and 10 μm pitch, and an optical detector. We characterize the system using Electron-Beam Lithography (EBL) pattern. Our prototype validates the imaging principle and opens the way to improve resolution by further miniaturizing the light sources.
Collapse
|
12
|
Muratov DS, Ishteev AR, Lypenko DA, Vanyushin VO, Gostishev P, Perova S, Saranin DS, Rossi D, Auf der Maur M, Volonakis G, Giustino F, Persson POÅ, Kuznetsov DV, Sinitskii A, Di Carlo A. Slot-Die-Printed Two-Dimensional ZrS 3 Charge Transport Layer for Perovskite Light-Emitting Diodes. ACS Appl Mater Interfaces 2019; 11:48021-48028. [PMID: 31793761 DOI: 10.1021/acsami.9b16457] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Liquid-phase exfoliation of zirconium trisulfide (ZrS3) was used to produce stable and ready-to-use inks for solution-processed semiconductor thin-film deposition. Ribbon-like layered crystals of ZrS3 were produced by the chemical vapor transport method and were then exfoliated in three different solvents: dimethylformamide, ethanol, and isopropyl alcohol. The resulting ZrS3 dispersions were compared for stability and the ability to form continuous films on top of the perovskite layer in light-emitting diodes with the ITO/PEDOT:PSS/MAPbBr3/2D-ZrS3/LiF/Al structure. Film deposition was performed by using either spray or slot-die coating methods. The slot-die coating route proved to produce better and more uniform films with respect to spray coating. We found that the 2D ZrS3 electron injection layer (EIL) stabilized the interface between the perovskite and LiF/Al cathode, reducing the turn-on voltage to 2.8 V and showing a luminance that does not degrade during voltage sweep. On the other hand, EIL-free devices show electroluminescence on the first voltage sweep that reduces almost to zero in the subsequent sweeps. Combining physical device simulation and density functional theory calculation, we are able to explain these results in terms of lowering the electron injection barrier at the cathode.
Collapse
Affiliation(s)
| | | | - Dmitry A Lypenko
- Laboratory of Electronic and Photonic Processes in Polymeric Nanostructural Materials , Russian Academy of Sciences A.N. Frumkin Institute of Physical Chemistry and Electrochemistry , Leninskiy Prospect 31k4 , Moscow 119071 , Russia
| | | | | | | | | | - Daniele Rossi
- CHOSE-Centre of Hybrid and Organic Solar Energy, Department of Electronics Engineering , University of Rome Tor Vergata , Rome 00133 , Italy
| | - Matthias Auf der Maur
- CHOSE-Centre of Hybrid and Organic Solar Energy, Department of Electronics Engineering , University of Rome Tor Vergata , Rome 00133 , Italy
| | - George Volonakis
- Department of Materials , University of Oxford , Parks Road , Oxford OX1 3PH , United Kingdom
| | - Feliciano Giustino
- Department of Materials , University of Oxford , Parks Road , Oxford OX1 3PH , United Kingdom
| | - Per O Å Persson
- Thin Film Physics Division, Department of Physics, Chemistry and Biology , Linköping University , Linköping 58183 , Sweden
| | | | - Alexander Sinitskii
- Department of Chemistry , University of Nebraska-Lincoln , Lincoln , Nebraska 68588 , United States
| | - Aldo Di Carlo
- CHOSE-Centre of Hybrid and Organic Solar Energy, Department of Electronics Engineering , University of Rome Tor Vergata , Rome 00133 , Italy
| |
Collapse
|
13
|
Barettin D, Auf der Maur M, di Carlo A, Pecchia A, Tsatsulnikov AF, Lundin WV, Sakharov AV, Nikolaev AE, Korytov M, Cherkashin N, Hÿtch MJ, Karpov SY. Carrier transport and emission efficiency in InGaN quantum-dot based light-emitting diodes. Nanotechnology 2017; 28:275201. [PMID: 28612754 DOI: 10.1088/1361-6528/aa75a8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
We present a study of blue III-nitride light-emitting diodes (LEDs) with multiple quantum well (MQW) and quantum dot (QD) active regions (ARs), comparing experimental and theoretical results. The LED samples were grown by metalorganic vapor phase epitaxy, utilizing growth interruption in the hydrogen/nitrogen atmosphere and variable reactor pressure to control the AR microstructure. Realistic configuration of the QD AR implied in simulations was directly extracted from HRTEM characterization of the grown QD-based structures. Multi-scale 2D simulations of the carrier transport inside the multiple QD AR have revealed a non-trivial pathway for carrier injection into the dots. Electrons and holes are found to penetrate deep into the multi-layer AR through the gaps between individual QDs and get into the dots via their side edges rather than via top and bottom interfaces. This enables a more homogeneous carrier distribution among the dots situated in different layers than among the laterally uniform quantum well (QWs) in the MQW AR. As a result, a lower turn-on voltage is predicted for QD-based LEDs, as compared to MQW ones. Simulations did not show any remarkable difference in the efficiencies of the MQW and QD-based LEDs, if the same recombination coefficients are utilized, i.e. a similar crystal quality of both types of LED structures is assumed. Measurements of the current-voltage characteristics of LEDs with both kinds of the AR have shown their close similarity, in contrast to theoretical predictions. This implies the conventional assumption of laterally uniform QWs not to be likely an adequate approximation for the carrier transport in MQW LED structures. Optical characterization of MQW and QD-based LEDs has demonstrated that the later ones exhibit a higher efficiency, which could be attributed to better crystal quality of the grown QD-based structures. The difference in the crystal quality explains the recently observed correlation between the growth pressure of LED structures and their efficiency and should be taken into account while further comparing performances of MQW and QD-based LEDs. In contrast to experimental results, our simulations did not reveal any advantages of using QD-based ARs over the MQW ones, if the same recombination constants are assumed for both cases. This fact demonstrates importance of accounting for growth-dependent factors, like crystal quality, which may limit the device performance. Nevertheless, a more uniform carrier injection into multi-layer QD ARs predicted by modeling may serve as the basis for further improvement of LED efficiency by lowering carrier density in individual QDs and, hence, suppressing the Auger recombination losses.
Collapse
Affiliation(s)
- Daniele Barettin
- UNICUSANO, Università degli Studi Niccolò Cusano-Telematica Rome, Italy. Department of Electronic Engineering, University of Rome 'Tor Vergata', Via del Politecnico 1, I-00133, Rome, Italy
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
14
|
Barettin D, Maur MAD, Carlo AD, Pecchia A, Tsatsulnikov AF, Sakharov AV, Lundin WV, Nikolaev AE, Usov SO, Cherkashin N, Hÿtch MJ, Karpov SY. Influence of electromechanical coupling on optical properties of InGaN quantum-dot based light-emitting diodes. Nanotechnology 2017; 28:015701. [PMID: 27897139 DOI: 10.1088/0957-4484/28/1/015701] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
The impact of electromechanical coupling on optical properties of light-emitting diodes (LEDs) with InGaN/GaN quantum-dot (QD) active regions is studied by numerical simulations. The structure, i.e. the shape and the average In content of the QDs, has been directly derived from experimental data on out-of-plane strain distribution obtained from the geometric-phase analysis of a high-resolution transmission electron microscopy image of an LED structure grown by metalorganic vapor-phase epitaxy. Using continuum [Formula: see text] calculations, we have studied first the lateral and full electromechanical coupling between the QDs in the active region and its impact on the emission spectrum of a single QD located in the center of the region. Our simulations demonstrate the spectrum to be weakly affected by the coupling despite the strong common strain field induced in the QD active region. Then we analyzed the effect of vertical coupling between vertically stacked QDs as a function of the interdot distance. We have found that QCSE gives rise to a blue-shift of the overall emission spectrum when the interdot distance becomes small enough. Finally, we compared the theoretical spectrum obtained from simulation of the entire active region with an experimental electroluminescence (EL) spectrum. While the theoretical peak emission wavelength of the selected central QD corresponded well to that of the EL spectrum, the width of the latter one was determined by the scatter in the structures of various QDs located in the active region. Good agreement between the simulations and experiment achieved as a whole validates our model based on realistic structure of the QD active region and demonstrates advantages of the applied approach.
Collapse
Affiliation(s)
- Daniele Barettin
- Department of Electronic Engineering, University of Rome 'Tor Vergata', Via del Politecnico 1, I-00133, Rome, Italy. UNICUSANO, Università degli Studi Niccolò Cusano-Telematica Rome, Italy
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
15
|
Pecchia A, Gentilini D, Rossi D, Auf der Maur M, Di Carlo A. Role of Ferroelectric Nanodomains in the Transport Properties of Perovskite Solar Cells. Nano Lett 2016; 16:988-992. [PMID: 26694919 DOI: 10.1021/acs.nanolett.5b03957] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Metropolis Monte Carlo simulations are used to construct minimal energy configurations by electrostatic coupling of rotating dipoles associated with each unit cell of a perovskite CH3NH3PbI3 crystal. Short-range antiferroelectric order is found, whereas at scales of 8-10 nm, we observe the formation of nanodomains, strongly influencing the electrostatics of the device. The models are coupled to drift-diffusion simulations to study the actual role of nanodomains in the I-V characteristics, especially focusing on charge separation and recombination losses. We demonstrate that holes and electrons separate into different nanodomains following different current pathways. From our analysis we can conclude that even antiferroelectric ordering can ultimately lead to an increase of photoconversion efficiencies thanks to a decrease of trap-assisted recombination losses and the formation of good current percolation patterns along domain edges.
Collapse
Affiliation(s)
- Alessandro Pecchia
- Consiglio Nazionale delle Ricerche, ISMN , Via Salaria km 29.300, 00017 Monterotondo, Italy
| | - Desirée Gentilini
- Dipartimento Ing. Elettronica, Università di Roma "Tor Vergata" , Via del Politecnico 1, 00133 Roma, Italy
| | - Daniele Rossi
- Dipartimento Ing. Elettronica, Università di Roma "Tor Vergata" , Via del Politecnico 1, 00133 Roma, Italy
| | - Matthias Auf der Maur
- Dipartimento Ing. Elettronica, Università di Roma "Tor Vergata" , Via del Politecnico 1, 00133 Roma, Italy
| | - Aldo Di Carlo
- Dipartimento Ing. Elettronica, Università di Roma "Tor Vergata" , Via del Politecnico 1, 00133 Roma, Italy
| |
Collapse
|
16
|
Auf der Maur M, Pecchia A, Penazzi G, Rodrigues W, Di Carlo A. Efficiency Drop in Green InGaN/GaN Light Emitting Diodes: The Role of Random Alloy Fluctuations. Phys Rev Lett 2016; 116:027401. [PMID: 26824564 DOI: 10.1103/physrevlett.116.027401] [Citation(s) in RCA: 82] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/12/2014] [Indexed: 05/28/2023]
Abstract
White light emitting diodes (LEDs) based on III-nitride InGaN/GaN quantum wells currently offer the highest overall efficiency for solid state lighting applications. Although current phosphor-converted white LEDs have high electricity-to-light conversion efficiencies, it has been recently pointed out that the full potential of solid state lighting could be exploited only by color mixing approaches without employing phosphor-based wavelength conversion. Such an approach requires direct emitting LEDs of different colors, including, in particular, the green-yellow range of the visible spectrum. This range, however, suffers from a systematic drop in efficiency, known as the "green gap," whose physical origin has not been understood completely so far. In this work, we show by atomistic simulations that a consistent part of the green gap in c-plane InGaN/GaN-based light emitting diodes may be attributed to a decrease in the radiative recombination coefficient with increasing indium content due to random fluctuations of the indium concentration naturally present in any InGaN alloy.
Collapse
Affiliation(s)
- Matthias Auf der Maur
- Department of Electronic Engineering, University of Rome Tor Vergata, Via del Politecnico 1, 00133 Rome, Italy
| | | | - Gabriele Penazzi
- Bremen Center for Computational Materials Science, University of Bremen, 28359 Bremen, Germany
| | - Walter Rodrigues
- Department of Electronic Engineering, University of Rome Tor Vergata, Via del Politecnico 1, 00133 Rome, Italy
| | - Aldo Di Carlo
- Department of Electronic Engineering, University of Rome Tor Vergata, Via del Politecnico 1, 00133 Rome, Italy
| |
Collapse
|
17
|
Zampetti A, Fallahpour AH, Dianetti M, Salamandra L, Santoni F, Gagliardi A, Auf der Maur M, Brunetti F, Reale A, Brown TM, Di Carlo A. Influence of the interface material layers and semiconductor energetic disorder on the open circuit voltage in polymer solar cells. ACTA ACUST UNITED AC 2015. [DOI: 10.1002/polb.23685] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Andrea Zampetti
- Department of Electronic Engineering; CHOSE, Centre for Hybrid and Solar Energy, University of Rome “Tor Vergata,” Via del Politecnico 1; 00133 Rome Italy
| | - Amir Hossein Fallahpour
- Department of Electronic Engineering; CHOSE, Centre for Hybrid and Solar Energy, University of Rome “Tor Vergata,” Via del Politecnico 1; 00133 Rome Italy
| | - Martina Dianetti
- Department of Electronic Engineering; CHOSE, Centre for Hybrid and Solar Energy, University of Rome “Tor Vergata,” Via del Politecnico 1; 00133 Rome Italy
| | - Luigi Salamandra
- Department of Electronic Engineering; CHOSE, Centre for Hybrid and Solar Energy, University of Rome “Tor Vergata,” Via del Politecnico 1; 00133 Rome Italy
| | - Francesco Santoni
- Department of Electronic Engineering; CHOSE, Centre for Hybrid and Solar Energy, University of Rome “Tor Vergata,” Via del Politecnico 1; 00133 Rome Italy
| | - Alessio Gagliardi
- Technische Universität München, Electrical and Computer Engineering; Arcisstr. 21 80333 München Germany
| | - Matthias Auf der Maur
- Department of Electronic Engineering; CHOSE, Centre for Hybrid and Solar Energy, University of Rome “Tor Vergata,” Via del Politecnico 1; 00133 Rome Italy
| | - Francesca Brunetti
- Department of Electronic Engineering; CHOSE, Centre for Hybrid and Solar Energy, University of Rome “Tor Vergata,” Via del Politecnico 1; 00133 Rome Italy
| | - Andrea Reale
- Department of Electronic Engineering; CHOSE, Centre for Hybrid and Solar Energy, University of Rome “Tor Vergata,” Via del Politecnico 1; 00133 Rome Italy
| | - Thomas M. Brown
- Department of Electronic Engineering; CHOSE, Centre for Hybrid and Solar Energy, University of Rome “Tor Vergata,” Via del Politecnico 1; 00133 Rome Italy
| | - Aldo Di Carlo
- Department of Electronic Engineering; CHOSE, Centre for Hybrid and Solar Energy, University of Rome “Tor Vergata,” Via del Politecnico 1; 00133 Rome Italy
| |
Collapse
|
18
|
Gagliardi A, Auf der Maur M, Gentilini D, di Fonzo F, Abrusci A, Snaith HJ, Divitini G, Ducati C, Di Carlo A. The real TiO2/HTM interface of solid-state dye solar cells: role of trapped states from a multiscale modelling perspective. Nanoscale 2015; 7:1136-1144. [PMID: 25484118 DOI: 10.1039/c4nr05208k] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
In this paper we present a multiscale simulation of charge transport in a solid-state dye-sensitized solar cell, where the real morphology between TiO2 and the hole transport material is included. The geometry of the interface is obtained from an electron tomography measurement and imported in a simulation software. Charge distribution, electric field and current densities are computed using the drift-diffusion model. We use this approach to investigate the electrostatic effect of trap states at the interface between the electron and hole transport materials. The simulations show that when the trapped electrons are not screened by external additives, the dynamics of holes is perturbed. Holes accumulate at the interface, enhancing recombination and reducing cell performance.
Collapse
Affiliation(s)
- Alessio Gagliardi
- Technische Universität München, Electrical and Computer Eng., Arcisstr. 21, 80333 München, Germany.
| | | | | | | | | | | | | | | | | |
Collapse
|
19
|
Barettin D, De Angelis R, Prosposito P, Auf der Maur M, Casalboni M, Pecchia A. Model of a realistic InP surface quantum dot extrapolated from atomic force microscopy results. Nanotechnology 2014; 25:195201. [PMID: 24763365 DOI: 10.1088/0957-4484/25/19/195201] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
We report on numerical simulations of a zincblende InP surface quantum dot (QD) on In₀.₄₈Ga₀.₅₂ buffer. Our model is strictly based on experimental structures, since we extrapolated a three-dimensional dot directly by atomic force microscopy results. Continuum electromechanical, [Formula: see text] bandstructure and optical calculations are presented for this realistic structure, together with benchmark calculations for a lens-shape QD with the same radius and height of the extrapolated dot. Interesting similarities and differences are shown by comparing the results obtained with the two different structures, leading to the conclusion that the use of a more realistic structure can provide significant improvements in the modeling of QDs fact, the remarkable splitting for the electron p-like levels of the extrapolated dot seems to prove that a realistic experimental structure can reproduce the right symmetry and a correct splitting usually given by atomistic calculations even within the multiband [Formula: see text] approach. Moreover, the energy levels and the symmetry of the holes are strongly dependent on the shape of the dot. In particular, as far as we know, their wave function symmetries do not seem to resemble to any results previously obtained with simulations of zincblende ideal structures, such as lenses or truncated pyramids. The magnitude of the oscillator strengths is also strongly dependent on the shape of the dot, showing a lower intensity for the extrapolated dot, especially for the transition between the electrons and holes ground state, as a result of a relevant reduction of the wave functions overlap. We also compare an experimental photoluminescence spectrum measured on an homogeneous sample containing about 60 dots with a numerical ensemble average derived from single dot calculations. The broader energy range of the numerical spectrum motivated us to perform further verifications, which have clarified some aspects of the experimental results and helped us to develop a suitable model for the spectrum, by assuming a not equiprobable weight from each dot, a model which is extremely consistent with the experimental data.
Collapse
Affiliation(s)
- Daniele Barettin
- Department of Electronic Engineering, University of Rome 'Tor Vergata', Via del Politecnico 1, I-00133 Rome, Italy
| | | | | | | | | | | |
Collapse
|
20
|
|