Impact of Orientational Glass Formation and Local Strain on Photo-Induced Halide Segregation in Hybrid Metal-Halide Perovskites.

Tim W J Van De Goor,Yun Liu,Nicola D Kelly,Timo Neumann,Sascha Feldmann,Bartomeu Monserrat,Cheng Liu,Michael A Jones,Felix Deschler,Sean A Bourelle,Thomas Winkler,Steffen P Emge,Siân E Dutton,Richard H Friend

doi:10.1021/acs.jpcc.1c03169

Tim W J Van De Goor, Yun Liu + Show 12 more

Open Access

PDF Available

https://doi.org/10.1021/acs.jpcc.1c03169

Copy DOI

Export

Save

Cite

Abstract
Highlights/Summary
Full-Text PDF
Similar Papers

Abstract

Listen

Band gap tuning of hybrid metal–halide perovskites by halide substitution holds promise for tailored light absorption in tandem solar cells and emission in light-emitting diodes. However, the impact of halide substitution on the crystal structure and the fundamental mechanism of photo-induced halide segregation remain open questions. Here, using a combination of temperature-dependent X-ray diffraction and calorimetry measurements, we report the emergence of a disorder- and frustration-driven orientational glass for a wide range of compositions in CH3NH3Pb(ClxBr1–x)3. Using temperature-dependent photoluminescence measurements, we find a correlation between halide segregation under illumination and local strains from the orientational glass. We observe no glassy behavior in CsPb(ClxBr1–x)3, highlighting the importance of the A-site cation for the structure and optoelectronic properties. Using first-principles calculations, we identify the local preferential alignment of the organic cations as the glass formation mechanism. Our findings rationalize the superior photostability of mixed-cation metal–halide perovskites and provide guidelines for further stabilization strategies.

Highlights

IntroductionThe dynamic disorder of the organic sublattice, which is not found in traditional inorganic semiconductors, has received widespread attention in the community.[11] It has long been known that the structure and properties of perovskites depend sensitively on their composition and disorder and this is no different in their hybrid counterparts
Mixed−halide hybrid perovskites MAPbX3 (X = Cl, Br, I) (MA = methylammonium, CH3NH3) are promising materials for light absorption in tandem solar cells and light emission in light-emitting diodes.[1,2] The power conversion efficiency of hybrid perovskite solar cells has recently exceeded 25%, rivalling single crystalline silicon technology.[3]
Using temperature-dependent PL measurements, we find that the persistence of local strains above the glass transition leads to photo-induced halide segregation, providing new evidence for the importance of static strain for the stability of mixedhalide hybrid perovskites

Summary

Introduction

The dynamic disorder of the organic sublattice, which is not found in traditional inorganic semiconductors, has received widespread attention in the community.[11] It has long been known that the structure and properties of perovskites depend sensitively on their composition and disorder and this is no different in their hybrid counterparts. At high excitation densities, neighboring polaronic strain fields start to overlap, homogenizing the energetic landscape and allowing for entropic remixing of the halides. This model does not explain the superior stability of certain mixed-halide compositions, and a comprehensive picture on the role of local static strain is still missing. We investigate the effect of halide substitution on the structure and optoelectronic properties of MAPb(ClxBr1−x)[3], by combining temperature-

Methods

Results

Conclusion