Chemische Gasphasendeposition von Organo-Halogenid-Perowskiten : Technologie- und Prozessentwicklung

Autor: Sanders, Simon
Přispěvatelé: Vescan, Andrei, Bacher, Gerd
Jazyk: němčina
Rok vydání: 2021
Předmět:
Zdroj: Aachen : RWTH Aachen University 1 Online-Ressource : Illustrationen, Diagramme (2021). doi:10.18154/RWTH-2021-03072 = Dissertation, Rheinisch-Westfälische Technische Hochschule Aachen, 2021
DOI: 10.18154/RWTH-2021-03072
Popis: Dissertation, Rheinisch-Westfälische Technische Hochschule Aachen, 2021; Aachen : RWTH Aachen University 1 Online-Ressource : Illustrationen, Diagramme (2021). = Dissertation, Rheinisch-Westfälische Technische Hochschule Aachen, 2021
Organo-halide perovskites are novel active materials for optoelectronics and are characterized by high absorption coefficients, large carrier mobilities and a couple of other exceptional properties. In the last decade, solar cells based on Pb-containing organo-halide perovskites have demonstrated an unprecedented improvement of power conversion efficiency (PCE) to currently over 25%. The best known representatives are methylammonium lead halides (CH$_{3}$NH$_{3}$PbX$_{3}$, short: MAPbX$_{3}$ with X e.g. I, Br). In parallel, methylammonium bismuth iodide ((CH$_{3}$NH$_{3}$)$_{3}$Bi$_{2}$I$_{9}$, abbreviated as MBI) has established itself as a less efficient, but chemically more stable and non-toxic model material. One hurdle on the way to commercialization of perovskite optoelectronics is the lack of deposition processes for industrial production. Up to now, perovskites have mostly been deposited on small areas by liquid processing using toxic solvents. One possible solution is chemical vapor deposition (CVD), which has hardly been explored so far for perovskites and promises precise process control, highest purity, better deposition efficiency and superior area scalability. Based on previous development work on a small prototype system, a completely new showerhead-based hot-wall CVD system for large-area deposition of perovskites was designed and started up. Its construction has been based on fluid-mechanical calculations and analyses of the thermal distribution inside the reactor. Specially constructed sublimation sources, a mixing-unit and a showerhead are included to ensure that the carrier gas flows loaded with precursors are uniformly mixed and then homogeneously distributed. Water cooling integrated in the sample holder allows the control of film formation on the substrate. Using the model material MBI, it was demonstrated that homogeneous CVD is possible on large-area substrates (> 100 cm²). Verification of the formed perovskite phase was performed by optical and crystallographic analyses. CVD of MAPbI$_{3}$ has been investigated for the application in photovoltaics. By choosing a suitable precursor ratio of 1.3 (organo- to metal- halide), stoichiometric MAPbI$_{3}$ films with a cubic crystal structure but a rather large porosity (26%) were obtained. Solar cell integration has been successfully demonstrated, but only PCE < 0.1% could be achieved so far. Reasons for this are most likely the release of the organic compound due to a high substrate temperature (120 °C) and the mentioned not yet optimized porous film morphology. For MAPbBr$_{3}$, considerable progress has already been made regarding the morphology by lowering the substrate temperature from initially 110 °C to 60 °C. In addition, the successful demonstration of light-emitting diodes (LEDs) based on CVD-CsPbBr$_{3}$ as a purely inorganic halide perovskite should be mentioned as well.
Published by RWTH Aachen University, Aachen
Databáze: OpenAIRE
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