1
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Fujita T, Hoshi T. Ab Initio Study of Charge Separation Dynamics and Pump-Probe Spectroscopy in the P3HT/PCBM Blend. J Phys Chem B 2023; 127:7615-7623. [PMID: 37639551 DOI: 10.1021/acs.jpcb.3c02458] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/31/2023]
Abstract
We develop a bottom-up computational method for excited-state dynamics and time-resolved spectroscopy signals in molecular aggregates, on the basis of ab initio excited-state calculations. As an application, we consider the charge separation dynamics and pump-probe spectroscopy in the amorphous P3HT/PCBM blend. To simulate quantum dynamics and time-resolved spectroscopy, the model Hamiltonian for single-excitation and double-excitation manifolds was derived on the basis of fragment-based excited-state calculations within the GW approximation and the Bethe-Salpeter equation. After elucidating the energetics of the electron-hole separation and examining linear absorption spectrum, we investigated the quantum dynamics of exciton and charge carriers in comparison with the pump-probe transient absorption spectra. In particular, we introduced the pump-probe excited-state absorption (ESA) anisotropy as a spectroscopic signature of charge carrier dynamics after exciton dissociation. We found that the charge separation dynamics can be probed by the pump-probe ESA anisotropy dynamics after charge-transfer excitations. The present study provides the fundamental information for understanding the experimental spectroscopy signals, by elucidating the relationship between the excited states, the exciton and charge carrier dynamics, and time-resolved spectroscopy.
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Affiliation(s)
- Takatoshi Fujita
- Institute for Quantum Life Science, National Institutes for Quantum Science and Technology, Chiba 263-8555, Japan
| | - Takeo Hoshi
- Department of Mechanical and Physical Engineering, Faculty of Engineering, Tottori University, Tottori-shi 680-8552, Tottori, Japan
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2
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Barsotti J, Perotto S, Candini A, Colombo E, Camargo FVA, Di Marco S, Zangoli M, Sardar S, Barker AJ, D'Andrea C, Cerullo G, Rozen S, Benfenati F, Di Maria F, Lanzani G. Core-Shell Architecture in Poly(3-hexylthiophene) Nanoparticles: Tuning of the Photophysical Properties for Enhanced Neuronal Photostimulation. ACS APPLIED MATERIALS & INTERFACES 2023; 15:13472-13483. [PMID: 36857156 DOI: 10.1021/acsami.2c20640] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
This study shows that entirely thiophene-based core@shell nanoparticles, in which the shell is made of the oxidized form of the core polymer (P3HT@PTDOx NPs), result in a type II interface at the particle surface. This enables the development of advanced photon nanotransducers with unique chemical-physical and biofunctional properties due to the core@shell nanoarchitecture. We demonstrate that P3HT@PTDOx NPs present a different spatial localization of the excitation energy with respect to the nonoxidized NPs, showing a prevalence of surface states as a result of a different alignment of the HOMO/LUMO energy levels between the core and shell. This allows for the efficient photostimulation of retinal neurons. Indeed, thanks to the stronger and longer-lived charge separation, P3HT@PTDOx NPs, administered subretinally in degenerate retinas from the blind Royal College of Surgeons rats, are more effective in photostimulation of inner retinal neurons than the gold standard P3HT NPs.
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Affiliation(s)
- Jonathan Barsotti
- Center for Nano Science and Technology @PoliMi, Istituto Italiano di Tecnologia, 20133 Milano, Italy
| | - Sara Perotto
- Center for Nano Science and Technology @PoliMi, Istituto Italiano di Tecnologia, 20133 Milano, Italy
- Dipartimento di Fisica, Politecnico di Milano, 20133 Milano, Italy
| | | | - Elisabetta Colombo
- IIT Centro di Neuroscienze e Tecnologie Sinaptiche, Centro di Biotecnologie Avanzate, IRCCS Ospedale Policlinico San Martino, 16132 Genova, Italy
| | | | - Stefano Di Marco
- IIT Centro di Neuroscienze e Tecnologie Sinaptiche, Centro di Biotecnologie Avanzate, IRCCS Ospedale Policlinico San Martino, 16132 Genova, Italy
| | | | - Samim Sardar
- Center for Nano Science and Technology @PoliMi, Istituto Italiano di Tecnologia, 20133 Milano, Italy
| | - Alex J Barker
- Center for Nano Science and Technology @PoliMi, Istituto Italiano di Tecnologia, 20133 Milano, Italy
| | - Cosimo D'Andrea
- Dipartimento di Fisica, Politecnico di Milano, 20133 Milano, Italy
| | - Giulio Cerullo
- Dipartimento di Fisica, Politecnico di Milano, 20133 Milano, Italy
| | - Shlomo Rozen
- School of Chemistry, Tel-Aviv University, 69978 Tel Aviv, Israel
| | - Fabio Benfenati
- IIT Centro di Neuroscienze e Tecnologie Sinaptiche, Centro di Biotecnologie Avanzate, IRCCS Ospedale Policlinico San Martino, 16132 Genova, Italy
| | | | - Guglielmo Lanzani
- Center for Nano Science and Technology @PoliMi, Istituto Italiano di Tecnologia, 20133 Milano, Italy
- Dipartimento di Fisica, Politecnico di Milano, 20133 Milano, Italy
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3
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Fluorescence dynamics of thiophene-based copolymer/fullerene-derivative system as solution and blend film. MONATSHEFTE FUR CHEMIE 2022. [DOI: 10.1007/s00706-022-02941-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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4
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Lukin L. Efficiency of exciton dissociation at the interface between a conjugated polymer and an electron acceptor with consideration for a two-dimensional arrangement of interfacial dipoles. Chem Phys 2021. [DOI: 10.1016/j.chemphys.2021.111327] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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5
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Takaya T, Enokida I, Furukawa Y, Iwata K. Direct Observation of Structure and Dynamics of Photogenerated Charge Carriers in Poly(3-hexylthiophene) Films by Femtosecond Time-Resolved Near-IR Inverse Raman Spectroscopy. Molecules 2019; 24:molecules24030431. [PMID: 30691007 PMCID: PMC6384712 DOI: 10.3390/molecules24030431] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2018] [Revised: 01/18/2019] [Accepted: 01/22/2019] [Indexed: 11/16/2022] Open
Abstract
The initial charge separation process of conjugated polymers is one of the key factors for understanding their conductivity. The structure of photogenerated transients in conjugated polymers can be observed by resonance Raman spectroscopy in the near-IR region because they exhibit characteristic low-energy transitions. Here, we investigate the structure and dynamics of photogenerated transients in a regioregular poly(3-hexylthiophene) (P3HT):[6,6]-phenyl-C61-butyric acid methyl ester (PCBM) blend film, as well as in a pristine P3HT film, using femtosecond time-resolved resonance inverse Raman spectroscopy in the near-IR region. The transient inverse Raman spectrum of the pristine P3HT film at 50 ps suggests coexistence of neutral and charged excitations, whereas that of the P3HT:PCBM blend film at 50 ps suggests formation of positive polarons with a different structure from those in an FeCl3-doped P3HT film. Time-resolved near-IR inverse Raman spectra of the blend film clearly show the absence of charge separation between P3HT and PCBM within the instrument response time of our spectrometer, while they indicate two independent pathways of the polaron formation with time constants of 0.3 and 10 ps.
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Affiliation(s)
- Tomohisa Takaya
- Department of Chemistry, Faculty of Science, Gakushuin University, 1-5-1 Mejiro, Toshima-ku, Tokyo 171-8588, Japan.
| | - Ippei Enokida
- Department of Advanced Science and Engineering, Waseda University, 3-4-1 Okubo, Shinjuku-ku, Tokyo 169-8555, Japan.
| | - Yukio Furukawa
- Department of Advanced Science and Engineering, Waseda University, 3-4-1 Okubo, Shinjuku-ku, Tokyo 169-8555, Japan.
| | - Koichi Iwata
- Department of Chemistry, Faculty of Science, Gakushuin University, 1-5-1 Mejiro, Toshima-ku, Tokyo 171-8588, Japan.
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6
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Carlino TM, Hu Q, Scott AM. Aggregate-Induced Self-Assembly and Ultrafast Dynamics of Light-Harvesting D-A-A Polymorphs. Macromol Rapid Commun 2018; 39:e1800391. [PMID: 30073723 DOI: 10.1002/marc.201800391] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2018] [Revised: 07/03/2018] [Indexed: 11/11/2022]
Abstract
Organic dipolar molecules are an emerging class of light harvesters useful in electronic applications and have captured new urgency with the design and synthesis of new molecular structures for device testing. However, research has not evolved beyond the cyclical thin film preparation-device testing-chemical structural modification approach. Without an understanding of polymorphism, molecular photophysics at the interface or metastable morphologies that regulate charge carrier dynamics, it is not obvious a priori if a new molecular structure will produce a suitable thin film morphology for superior device performance without developing structure-function relationships that consider morphology and photophysics. Dipolar, light harvesting molecules are synthesized with a covalent, para-functionalized triphenylamine donor (D) and acceptor (A) in π-conjugated structures, D-A1 and D-A1 -A2 , that have previously achieved 9.6% power conversion efficiency in thermally evaporated organic solar cell devices with C70 . Solution processing and morphological manipulation are hypothesized to reduce ultrafast radiative charge recombination, unique to dipolar structures, that prevents full charge separation to the fullerene. The photophysics of the D-A interface using femtosecond transient absorption spectroscopy is explained, and microscopy data reveal a newly discovered, supramolecular amorphous polymer metastable state presented as a transient absorption assisted strategy for photofunctional polymorph design.
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Affiliation(s)
- Thomas M Carlino
- Department of Chemistry, University of Miami, 1301 Memorial Drive, Coral Gables, FL 33146, USA
| | - Qiaoyu Hu
- Department of Chemistry, University of Miami, 1301 Memorial Drive, Coral Gables, FL 33146, USA
| | - Amy M Scott
- Department of Chemistry, University of Miami, 1301 Memorial Drive, Coral Gables, FL 33146, USA
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7
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Mazza MMA, Yamazaki S, Mai DX, Padgaonkar S, Peurifoy S, Goncalves A, Wu YL, Hu Q, Scott AM. Photoinduced charge recombination in dipolar D-A-A photonic liquid crystal polymorphs. Phys Chem Chem Phys 2017; 19:4588-4596. [PMID: 28124694 DOI: 10.1039/c6cp08631d] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
A hexylalkoxy dipolar D-A-A molecule [7-(4-N,N-(bis(4-hexyloxyphenyl)amino)phenyl)-2,1,3-(benzothia-diazol-4-yl)methylene]propane-dinitrile, (C6-TPA-BT-CN) has been synthesized and the photophysics studied via femtosecond transient absorption spectroscopy (FsTA) in toluene and in amorphous and liquid crystalline spherulite thin films. Two spherulite macromolecular crystalline phases (banded, and non-banded) were observed through concentration dependent, solution processing techniques and are birefringent with a negative sign of elongation. A dramatic change in the electronic absorption from blue in amorphous films to green in spherulites was observed, and the molecular orientation was determined through the combined analysis of polarized light microscopy, X-ray diffraction, and scanning electron microscopy. FsTA was performed on amorphous films and show complex charge recombination dynamics, and a Stark effect, characterized from the combined TPA+˙ and [BT-CN]-˙ spectroscopic signatures at 450 nm and 510 nm and identified through spectroelectrochemistry. Radical cation dynamics of TPA+˙ was observed selectively at 750 nm with >503.3 ps (18%) recombination kinetics resulting in a rather significant yield of free charge carriers in amorphous films and consistent with previous reports on energetically disordered blend films. However, photoexcitation on large, non-banded spherulites areas (>250 μm) reveal average monoexponential charge recombination lifetimes of 169.2 ps from delocalized states similar to those observed in amorphous films and are 5× longer-lived than previous reports [Chang et al., J. Am. Chem. Soc., 2013, 135, 8790] of a related methyl-DPAT-BT-CN whose amorphous thin films were prepared through vapor deposition. Thus, the correlation between the microstructure of the blend film and the photoinduced radical pair dynamics described here is critical for developing a fundamental understanding of how dipolar states contribute to the charge carrier yield in a disordered energy system.
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Affiliation(s)
- Mercedes M A Mazza
- Department of Chemistry, University of Miami, 1301 Memorial Drive, Coral Gables, FL 33146, USA.
| | - Shiori Yamazaki
- Department of Chemistry, University of Miami, 1301 Memorial Drive, Coral Gables, FL 33146, USA.
| | - Dieu X Mai
- Department of Chemistry, University of Miami, 1301 Memorial Drive, Coral Gables, FL 33146, USA.
| | - Suyog Padgaonkar
- Department of Chemistry, University of Miami, 1301 Memorial Drive, Coral Gables, FL 33146, USA.
| | - Samuel Peurifoy
- Department of Chemistry, University of Miami, 1301 Memorial Drive, Coral Gables, FL 33146, USA.
| | - Ariane Goncalves
- Department of Chemistry, University of Miami, 1301 Memorial Drive, Coral Gables, FL 33146, USA.
| | - Yi-Lin Wu
- Department of Chemistry, Northwestern University, Evanston, IL 60208, USA
| | - Qiaoyu Hu
- Department of Chemistry, University of Miami, 1301 Memorial Drive, Coral Gables, FL 33146, USA.
| | - Amy M Scott
- Department of Chemistry, University of Miami, 1301 Memorial Drive, Coral Gables, FL 33146, USA.
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8
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Wilcox DE, Lee MH, Sykes ME, Niedringhaus A, Geva E, Dunietz BD, Shtein M, Ogilvie JP. Ultrafast Charge-Transfer Dynamics at the Boron Subphthalocyanine Chloride/C60 Heterojunction: Comparison between Experiment and Theory. J Phys Chem Lett 2015; 6:569-575. [PMID: 26261981 DOI: 10.1021/jz502278k] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Photoinduced charge-transfer (CT) processes play a key role in many systems, particularly those relevant to organic photovoltaics and photosynthesis. Advancing the understanding of CT processes calls for comparing their rates measured via state-of-the-art time-resolved interface-specific spectroscopic techniques with theoretical predictions based on first-principles molecular models. We measure charge-transfer rates across a boron subphthalocyanine chloride (SubPc)/C60 heterojunction, commonly used in organic photovoltaics, via heterodyne-detected time-resolved second-harmonic generation. We compare these results to theoretical predictions based on a Fermi's golden rule approach, with input parameters obtained using first-principles calculations for two different equilibrium geometries of a molecular donor-acceptor in a dielectric continuum model. The calculated rates (∼2 ps(-1)) overestimate the measured rates (∼0.1 ps(-1)), which is consistent with the expectation that the calculated rates represent an upper bound over the experimental ones. The comparison provides valuable understanding of how the structure of the electron donor-acceptor interface affects the CT kinetics in organic photovoltaic systems.
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Affiliation(s)
- Daniel E Wilcox
- †Department of Physics, University of Michigan, 450 Church Street, Ann Arbor, Michigan 48109, United States
| | - Myeong H Lee
- ∥Department of Chemistry, Kent State University, 214 Williams Hall, Kent, Ohio 44242, United States
| | | | - Andrew Niedringhaus
- †Department of Physics, University of Michigan, 450 Church Street, Ann Arbor, Michigan 48109, United States
| | | | - Barry D Dunietz
- ∥Department of Chemistry, Kent State University, 214 Williams Hall, Kent, Ohio 44242, United States
| | | | - Jennifer P Ogilvie
- †Department of Physics, University of Michigan, 450 Church Street, Ann Arbor, Michigan 48109, United States
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9
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Abate A, Pérez-Tejada R, Wojciechowski K, Foster JM, Sadhanala A, Steiner U, Snaith HJ, Franco S, Orduna J. Phosphonic anchoring groups in organic dyes for solid-state solar cells. Phys Chem Chem Phys 2015; 17:18780-9. [DOI: 10.1039/c5cp02671g] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Performance of new metal-free organic dyes for solid-state dye-sensitized solar cells with carboxylic and phosphonic acids as TiO2 anchoring groups.
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Affiliation(s)
- Antonio Abate
- Department of Physics
- University of Oxford
- Oxford
- UK
- Cavendish Laboratory
| | - Raquel Pérez-Tejada
- Instituto de Ciencia Materiales de Aragón
- Departamento de Química Orgánica
- Universidad de Zaragoza-CSIC
- Spain
| | | | - Jamie M. Foster
- Department of Mathematics & Statistics
- McMaster University
- Hamilton
- Canada
| | - Aditya Sadhanala
- Cavendish Laboratory
- Department of Physics
- University of Cambridge
- Cambridge
- UK
| | - Ullrich Steiner
- Cavendish Laboratory
- Department of Physics
- University of Cambridge
- Cambridge
- UK
| | | | - Santiago Franco
- Instituto de Ciencia Materiales de Aragón
- Departamento de Química Orgánica
- Universidad de Zaragoza-CSIC
- Spain
| | - Jesús Orduna
- Instituto de Ciencia Materiales de Aragón
- Departamento de Química Orgánica
- Universidad de Zaragoza-CSIC
- Spain
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10
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Wilcox DE, Sykes ME, Niedringhaus A, Shtein M, Ogilvie JP. Heterodyne-detected and ultrafast time-resolved second-harmonic generation for sensitive measurements of charge transfer. OPTICS LETTERS 2014; 39:4274-4277. [PMID: 25121705 DOI: 10.1364/ol.39.004274] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
In organic photovoltaics many key ultrafast processes occur at the interface between electron donor and acceptor molecules. Traditional ultrafast spectroscopies, such as pump-probe or time-resolved fluorescence, are not ideal for studying the interface because most of their signal is from the bulk material. Time-resolved second-harmonic generation (TRSHG) spectroscopy solves this problem by only generating signal from the interface. We demonstrate an optically heterodyned TRSHG to reduce the impact of stray light, enhance sensitivity, and detect the full complex signal field.
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11
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Tapping PC, Kee TW. Optical Pumping of Poly(3-hexylthiophene) Singlet Excitons Induces Charge Carrier Generation. J Phys Chem Lett 2014; 5:1040-1047. [PMID: 26270985 DOI: 10.1021/jz500217f] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The dynamics of high-energy excitons of poly(3-hexylthiophene) (P3HT) are shown to consist of torsional relaxation and exciton dissociation to form free carriers. In this work, we use pump-push-probe femtosecond transient absorption spectroscopy to study the highly excited states of P3HT in solution. P3HT excitons are generated using a pump pulse (400 nm) and allowed to relax to the lowest-lying excited state before re-excitation using a push pulse (900 or 1200 nm), producing high-energy excitons that decay back to the original excited state with both subpicosecond (0.16 ps) and picosecond (2.4 ps) time constants. These dynamics are consistent with P3HT torsional relaxation, with the 0.16 ps time constant assigned to ultrafast inertial torsional relaxation. Additionally, the signal exhibits an incomplete recovery, indicating dissociation of high-energy excitons to form charge carriers due to excitation by the push pulse. Our analysis indicates that charge carriers are formed with a yield of 11%.
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Affiliation(s)
- Patrick C Tapping
- Department of Chemistry, The University of Adelaide, South Australia 5005, Australia
| | - Tak W Kee
- Department of Chemistry, The University of Adelaide, South Australia 5005, Australia
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12
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Gao J, Grey JK. Resonance Raman overtones reveal vibrational displacements and dynamics of crystalline and amorphous poly(3-hexylthiophene) chains in fullerene blends. J Chem Phys 2013; 139:044903. [DOI: 10.1063/1.4815819] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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13
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Kumar RSS, Grancini G, Petrozza A, Abrusci A, Snaith HJ, Lanzani G. Effect of polymer morphology on P3HT-based solid-state dye sensitized solar cells: an ultrafast spectroscopic investigation. OPTICS EXPRESS 2013; 21 Suppl 3:A469-A474. [PMID: 24104435 DOI: 10.1364/oe.21.00a469] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Solid-state dye sensitized solar cell devices are fabricated with poly(3-hexylthiophene) (P3HT) as the hole transporting layer. Upon annealing treatment we obtained ≈ 70% increase in the device efficiency compared to un-annealed devices. Our investigation, by means of ultrafast transient absorption spectroscopic characterization, correlates the increased device performances to a more efficient hole-transfer at the dye/polymer interface in the thermally treated P3HT.
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14
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Clafton SN, Huang DM, Massey WR, Kee TW. Femtosecond Dynamics of Excitons and Hole-Polarons in Composite P3HT/PCBM Nanoparticles. J Phys Chem B 2013; 117:4626-33. [DOI: 10.1021/jp308876z] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Affiliation(s)
- Scott N. Clafton
- School of Chemistry & Physics, The University of Adelaide, Adelaide, South Australia 5005, Australia
| | - David M. Huang
- School of Chemistry & Physics, The University of Adelaide, Adelaide, South Australia 5005, Australia
| | - William R. Massey
- School of Chemistry & Physics, The University of Adelaide, Adelaide, South Australia 5005, Australia
| | - Tak W. Kee
- School of Chemistry & Physics, The University of Adelaide, Adelaide, South Australia 5005, Australia
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15
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Bakulin AA, Dimitrov SD, Rao A, Chow PCY, Nielsen CB, Schroeder BC, McCulloch I, Bakker HJ, Durrant JR, Friend RH. Charge-Transfer State Dynamics Following Hole and Electron Transfer in Organic Photovoltaic Devices. J Phys Chem Lett 2013; 4:209-215. [PMID: 26291233 DOI: 10.1021/jz301883y] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The formation of bound electron-hole pairs, also called charge-transfer (CT) states, in organic-based photovoltaic devices is one of the dominant loss mechanisms hindering performance. Whereas CT state dynamics following electron transfer from donor to acceptor have been widely studied, there is not much known about the dynamics of bound CT states produced by hole transfer from the acceptor to the donor. In this letter, we compare the dynamics of CT states formed in the different charge-transfer pathways in a range of model systems. We show that the nature and dynamics of the generated CT states are similar in the case of electron and hole transfer. However the yield of bound and free charges is observed to be strongly dependent on the HOMOD-HOMOA and LUMOD-LUMOA energy differences of the material system. We propose a qualitative model in which the effects of static disorder and sampling of states during the relaxation determine the probability of accessing CT states favorable for charge separation.
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Affiliation(s)
- Artem A Bakulin
- †FOM Institute AMOLF, Science Park 104, Amsterdam, The Netherlands
- ‡Cavendish Laboratory, University of Cambridge, JJ Thomson Ave, Cambridge CB3 0HE, United Kingdom
| | - Stoichko D Dimitrov
- §Centre for Plastic Electronics, Department of Chemistry, Imperial College London, Exhibition Road, London SW7 2AZ, United Kingdom
| | - Akshay Rao
- ‡Cavendish Laboratory, University of Cambridge, JJ Thomson Ave, Cambridge CB3 0HE, United Kingdom
| | - Philip C Y Chow
- ‡Cavendish Laboratory, University of Cambridge, JJ Thomson Ave, Cambridge CB3 0HE, United Kingdom
| | - Christian B Nielsen
- §Centre for Plastic Electronics, Department of Chemistry, Imperial College London, Exhibition Road, London SW7 2AZ, United Kingdom
| | - Bob C Schroeder
- §Centre for Plastic Electronics, Department of Chemistry, Imperial College London, Exhibition Road, London SW7 2AZ, United Kingdom
| | - Iain McCulloch
- §Centre for Plastic Electronics, Department of Chemistry, Imperial College London, Exhibition Road, London SW7 2AZ, United Kingdom
| | - Huib J Bakker
- †FOM Institute AMOLF, Science Park 104, Amsterdam, The Netherlands
| | - James R Durrant
- §Centre for Plastic Electronics, Department of Chemistry, Imperial College London, Exhibition Road, London SW7 2AZ, United Kingdom
| | - Richard H Friend
- ‡Cavendish Laboratory, University of Cambridge, JJ Thomson Ave, Cambridge CB3 0HE, United Kingdom
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