Local study on the role of defects in the photophysics of mixed halide perovskites
Juan F. Galisteo-López a, David O. Tiede b, Mauricio E. Calvo a, Hernán Míguez a
a Instituto de Ciencia de Materiales de Sevilla (CSIC-US) , 41092, Seville, Spain
b University of Münster, Institute of Physics, Münster, 48149, Germany
nanoGe Perovskite Conferences
Proceedings of International Conference on Perovskite Thin Film Photovoltaics and Perovskite Photonics and Optoelectronics (NIPHO20)
Sevilla, Spain, 2020 February 23rd - 25th
Organizer: Hernán Míguez
Oral, Juan F. Galisteo-López, presentation 029
Publication date: 25th November 2019

Photophysical changes taking place in mixed halide perovskites under illumination are amongst the most striking evidences of the instability of this material which constitutes the main bottleneck for its future commercialization. [1] A vast amount of (seldom conflicting) experimental evidence has appeared over the past few years pointing towards the defect-assisted formation of an iodide-rich phase through which carrier recombination is channeled. Such phase separation constitutes a severe limitation for devices, leading to a decrease in open circuit voltage in tandem solar cells [2] and modifying the spectral ouput of LEDs, the two main application envisaged for mixed halide perovskites. In spite of this evidence, the ultimate mechanism responsible for the migration of halide ions under illumination is still under debate.

In this work we have carried out a spectrally-resolved micro photoluminescence study of CH3NH3PbBrxI3-x thin films under different external conditions in order to shed more light on the origin of the so-called Hoke effect. This has allowed us to explore the correlation between the dynamics of photophysical changes and the presence of lattice defects. Modifying the surrounding atmosphere, which has been demonstrated to influence these changes, [3,4] and the synthesis conditions to add vacancies or interstitials we discuss on the role of different types of defects on the photophysics of these materials.

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