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Alessi B, Macias-Montero M, Maddi C, Maguire P, Svrcek V, Mariotti D. Bridging energy bands to the crystalline and amorphous states of Si QDs. Faraday Discuss 2020; 222:390-404. [PMID: 32133465 DOI: 10.1039/c9fd00103d] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The relationship between the crystallization process and opto-electronic properties of silicon quantum dots (Si QDs) synthesized by atmospheric pressure plasmas (APPs) is studied in this work. The synthesis of Si QDs is carried out by flowing silane as a gas precursor in a plasma confined to a submillimeter space. Experimental conditions are adjusted to propitiate the crystallization of the Si QDs and produce QDs with both amorphous and crystalline character. In all cases, the Si QDs present a well-defined mean particle size in the range of 1.5-5.5 nm. Si QDs present optical bandgaps between 2.3 eV and 2.5 eV, which are affected by quantum confinement. Plasma parameters evaluated using optical emission spectroscopy are then used as inputs for a collisional plasma model, whose calculations yield the surface temperature of the Si QDs within the plasma, justifying the crystallization behavior under certain experimental conditions. We measure the ultraviolet-visible optical properties and electronic properties through various techniques, build an energy level diagram for the valence electrons region as a function of the crystallinity of the QDs, and finally discuss the integration of these as active layers of all-inorganic solar cells.
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Affiliation(s)
- Bruno Alessi
- Nanotechnology and Integrated Bio-Engineering Centre (NIBEC), Ulster University, Newtownabbey, BT37 0QB, UK.
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McDonald C, Ni C, Švrček V, Lozac'h M, Connor PA, Maguire P, Irvine JTS, Mariotti D. Zero-dimensional methylammonium iodo bismuthate solar cells and synergistic interactions with silicon nanocrystals. NANOSCALE 2017; 9:18759-18771. [PMID: 29168534 DOI: 10.1039/c7nr05764d] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Organometal trihalide perovskite solar cells have attracted monumental attention in recent years. Today's best devices, based on a three-dimensional perovskite structure of corner-sharing PbI6 octahedra, are unstable, toxic, and display hysteresis in current-voltage measurements. We present zero-dimensional organic-inorganic hybrid solar cells based on methylammonium iodo bismuthate (CH3NH3)3(Bi2I9) (MABI) comprising a Bi2I9 bioctahedra and observe very low hysteresis for scan rates in the broad range of 150 mV s-1 to 1500 mV s-1 without any interfacial layer engineering. We confirm good stability for devices produced and stored in open air without humidity control. The MABI structure can also accommodate silicon nanocrystals, leading to an enhancement in the short-circuit current. Through the material MABI, we demonstrate a promising alternative to the organometal trihalide perovskite class and present a model material for future composite third-generation photovoltaics.
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Affiliation(s)
- Calum McDonald
- Nanotechnology and Integrated Bioengineering Centre, Ulster University, BT37 0QB, UK.
| | - Chengsheng Ni
- School of Chemistry, University of St Andrews, KY16 9ST, UK
| | - Vladimir Švrček
- Research Center for Photovoltaics, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba 305-8568, Japan
| | - Mickaël Lozac'h
- Research Center for Photovoltaics, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba 305-8568, Japan
| | - Paul A Connor
- School of Chemistry, University of St Andrews, KY16 9ST, UK
| | - Paul Maguire
- Nanotechnology and Integrated Bioengineering Centre, Ulster University, BT37 0QB, UK.
| | | | - Davide Mariotti
- Nanotechnology and Integrated Bioengineering Centre, Ulster University, BT37 0QB, UK.
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Macias-Montero M, Askari S, Mitra S, Rocks C, Ni C, Svrcek V, Connor PA, Maguire P, Irvine JTS, Mariotti D. Energy band diagram of device-grade silicon nanocrystals. NANOSCALE 2016; 8:6623-6628. [PMID: 26939617 DOI: 10.1039/c5nr07705b] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Device grade silicon nanocrystals (NCs) are synthesized using an atmospheric-pressure plasma technique. The Si NCs have a small and well defined size of about 2.3 nm. The synthesis system allows for the direct creation of thin films, enabling a range of measurements to be performed and easy implementation of this material in different devices. The chemical stability of the Si NCs is evaluated, showing relatively long-term durability thanks to hydrogen surface terminations. Optical and electrical characterization techniques, including Kelvin probe, ultraviolet photoemission spectroscopy and Mott-Schottky analysis, are employed to determine the energy band diagram of the Si NCs.
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Affiliation(s)
- M Macias-Montero
- Nanotechnology & Integrated Bio-Engineering Centre (NIBEC), University of Ulster, BT37 0QB, UK.
| | - S Askari
- Nanotechnology & Integrated Bio-Engineering Centre (NIBEC), University of Ulster, BT37 0QB, UK.
| | - S Mitra
- Nanotechnology & Integrated Bio-Engineering Centre (NIBEC), University of Ulster, BT37 0QB, UK.
| | - C Rocks
- Nanotechnology & Integrated Bio-Engineering Centre (NIBEC), University of Ulster, BT37 0QB, UK.
| | - C Ni
- School of Chemistry, University of St Andrews, St Andrews, Fife, KY16 9ST, UK
| | - V Svrcek
- Research Center for Photovoltaic Technologies, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, 305-8568, Japan
| | - P A Connor
- School of Chemistry, University of St Andrews, St Andrews, Fife, KY16 9ST, UK
| | - P Maguire
- Nanotechnology & Integrated Bio-Engineering Centre (NIBEC), University of Ulster, BT37 0QB, UK.
| | - J T S Irvine
- School of Chemistry, University of St Andrews, St Andrews, Fife, KY16 9ST, UK
| | - D Mariotti
- Nanotechnology & Integrated Bio-Engineering Centre (NIBEC), University of Ulster, BT37 0QB, UK.
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Abstract
Quantum confined silicon nanocrystals (Si-ncs) exhibit intriguing properties due to silicon's indirect bandgap and their highly reactive surfaces. In particular the interplay of quantum confinement with surface effects reveals a complex scenario, which can complicate the interpretation of Si-nc properties and prediction of their corresponding behaviour. At the same time, the complexity and interplay of the different mechanisms in Si-ncs offer great opportunities with characteristics that may not be achievable with other nano-systems. In this context, a variety of carefully surface-engineered Si-ncs are highly desirable both for improving our understanding of Si-nc photo-physics and for their successful integration in application devices. Here we firstly highlight a selection of theoretical efforts and experimental surface engineering approaches and secondly we focus on recent surface engineering results that have utilized novel plasma-liquid interactions.
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Affiliation(s)
- Davide Mariotti
- Nanotechnology & Integrated Bio-Engineering Centre-NIBEC, University of Ulster, UK.
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Electronic interactions of silicon nanocrystals and nanocarbon materials: Hybrid solar cells. PURE APPL CHEM 2012. [DOI: 10.1351/pac-con-12-01-12] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Hybrid inorganic/nanocarbon solar cells represent low-cost solutions for the large-scale manufacturing of energy conversion devices. Here we discuss results that relate to the electronic interactions of nanocarbon materials with freestanding and surfactant-free silicon nanocrystals (Si-ncs) with quantum confinement effects, integrated in bulk-heterojunction solar cells. In particular, we demonstrate the feasibility of bulk-heterojunction photovoltaic solar cells that consist of Si-ncs combined with fullerenes or with semiconducting single-walled carbon nanotubes (SWCNTs). We show that the energy levels between Si-ncs with energy gap exceeding 1.75 eV and fullerenes are adequate for exciton dissociation and carriers (electrons/holes) generation and that hybrid solar cells formed by Si-ncs and semi-conducting SWCNTs favor exciton dissociation only when a distinct chiral index [i.e., (7,5)] is used. While fullerenes show energy conversion capabilities in the visible spectral region (1.7–3.1 eV), the cells containing the SWCNTs, in comparison, have a considerably expanded optical response covering a broad range of the spectrum (0.9–3.1 eV).
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Chubilleau C, Lenoir B, Migot S, Dauscher A. Laser fragmentation in liquid medium: A new way for the synthesis of PbTe nanoparticles. J Colloid Interface Sci 2011; 357:13-7. [DOI: 10.1016/j.jcis.2011.01.057] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2010] [Revised: 12/08/2010] [Accepted: 01/14/2011] [Indexed: 10/18/2022]
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