Dresden 2020 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 50: Perovskite and photovoltaics IV (joint session HL/CPP)
HL 50.4: Talk
Wednesday, March 18, 2020, 15:45–16:00, POT 251
Spatially elucidating the role of defects in the photophysics of mixed halide perovskites — •David O. Tiede1, Juan F. Galisteo-López2, Mauricio E. Calvo2, and Hernán Míguez2 — 1University of Münster, Institute of Physics, Münster, Germany — 2Instituto de Ciencia de Materiales de Sevilla (CSIC-US), Seville, Spain
Light-induced structural changes in mixed halide perovskites are among the most critical instabilities of this material that hamper their future commercialization. In particular, reversible light-induced phase segregation and its corresponding spectral cha ges in emission is a major drawback in precise bandgap tuning, which is crucial for both efficient light harvesting in tandem solar cells and modifying the spectral output of LEDs. Over the past years, various reports have pointed towards the critical role of defects in this process and a strong dependency on environmental effects. However, the exact mechanism of the migration of halides is still under debate.
In this work we have carried out a spectrally-resolved micro-photoluminescence experiments, employing a confocal microscope, to study the formation of iodine-rich domains in CH3NH3PbBrxI3-x thin films. With macroscopic measurements we verify that defects account for a dominant role on phase segregation and cause the formation of iodine-rich domains in minor parts of the material. By modifying the atmospheric conditions and changing the stoichiometry of halide components during the synthesis, we clarify the impact of vacancies and interstitials on the photophysics of these materials.