期刊
ACS NANO
卷 15, 期 12, 页码 20391-20402出版社
AMER CHEMICAL SOC
DOI: 10.1021/acsnano.1c08726
关键词
large bandgap perovskites; contact potential difference; inhomogeneity; phase instability; flat grains; ion migration; defects
类别
资金
- CNMS user facility
- National Research Foundation of Korea (NRF) - Korea Government (MSIP) [NRF-2020R1A2C3009115]
- Australian Centre for Advanced Photovoltaics [RG193402-I]
The optoelectronic performance of organic-inorganic halide perovskite-based devices has been improved, especially in solar cells using mixed-cations and mixed-halides. Research on the microstructural behavior of mixed perovskites identified potential factors for process optimization to further enhance performance.
The optoelectronic performance of organic-inorganic halide perovskite (OIHP)-based devices has been improved in recent years. Particularly, solar cells fabricated using mixed-cations and mixed-halides have outperformed their single-cation and single-halide counterparts. Yet, a systematic evaluation of the microstructural behavior of mixed perovskites is missing despite their known composition-dependent photoinstability. Here, we explore microstructural inhomogeneity in (FAPbI(3))(x)(MAPbBr(3))(1-x) using advanced scanning probe microscopy techniques. Contact potential difference (CPD) maps measured by Kelvin probe force microscopy show an increased fraction of grains exhibiting a low CPD with flat topography as MAPbBr(3) concentration is increased. The higher portion of low CPD contributes to asymmetric CPD distribution curves. Chemical analysis reveals these grains being rich in MA, Pb, and I. The composition-dependent phase segregation upon illumination, reflected on the emergence of a low-energy peak emission in the original photoluminescence spectra, arises from the formation of such grains with flat topology. Bias-dependent piezo-response force microscopy measurements, in these grains, further confirm vigorous ion migration and cause a hysteretic piezo-response. Our results, therefore, provide insights into the microstructural evaluation of phase segregation and ion migration in OIHPs pointing toward process optimization as a mean to further enhance their optoelectronic performance.
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