Excess charge-carrier induced instability of hybrid perovskites

Yuze Lin,Chunxiong Bao,Yanfa Yan,Jingjing Zhao,Yehao Deng,Peter N Rudd,Yanjun Fang,Yongbo Yuan,Zhenhua Yu,Jinsong Huang,Bo Chen

doi:10.1038/s41467-018-07438-w

Abstract

Identifying the origin of intrinsic instability for organic–inorganic halide perovskites (OIHPs) is crucial for their application in electronic devices, including solar cells, photodetectors, radiation detectors, and light-emitting diodes, as their efficiencies or sensitivities have already been demonstrated to be competitive with commercial available devices. Here we show that free charges in OIHPs, whether generated by incident light or by current-injection from electrodes, can reduce their stability, while efficient charge extraction effectively stabilizes the perovskite materials. The excess of both holes and electrons reduce the activation energy for ion migration within OIHPs, accelerating the degradation of OIHPs, while the excess holes and electrons facilitate the migration of cations or anions, respectively. OIHP solar cells capable of efficient charge-carrier extraction show improved light stability under regular operation conditions compared to an open-circuit condition where the photo-generated charges are confined in the perovskite layers.

Highlights

Identifying the origin of intrinsic instability for organic–inorganic halide perovskites (OIHPs) is crucial for their application in electronic devices, including solar cells, photodetectors, radiation detectors, and light-emitting diodes, as their efficiencies or sensitivities have already been demonstrated to be competitive with commercial available devices
It is found that the excess of both holes and electrons can accelerate the degradation of perovskite materials, which can be explained by the excess free charges facilitating ion migration within OIHPs
Though it has been well established that some mixed halide perovskites have phase separation under illumination[38,39,40,41,42,43], an anomalously fast phase separation of a WBG OIHP, FA0.85Cs0.15Pb(I0.6Br0.4)[3] (FA = HC(NH2)2), was observed under illumination when deposited on poly(triaryl amine) (PTAA) coated glass substrates, as compared to control samples deposited directly on glass substrate

Summary

Introduction

Identifying the origin of intrinsic instability for organic–inorganic halide perovskites (OIHPs) is crucial for their application in electronic devices, including solar cells, photodetectors, radiation detectors, and light-emitting diodes, as their efficiencies or sensitivities have already been demonstrated to be competitive with commercial available devices. We show that free charges in OIHPs, whether generated by incident light or by current-injection from electrodes, can reduce their stability, while efficient charge extraction effectively stabilizes the perovskite materials. The excess of both holes and electrons reduce the activation energy for ion migration within OIHPs, accelerating the degradation of OIHPs, while the excess holes and electrons facilitate the migration of cations or anions, respectively. It is found that the excess of both holes and electrons can accelerate the degradation of perovskite materials, which can be explained by the excess free charges facilitating ion migration within OIHPs. The photo-generated electrons and holes show different impacts on the migration of cations and anions, with reduced migration energy barriers for cation by holes and for anion by electrons. The excesscharge induced material degradation is shown to be suppressed by efficient extraction of the photo-generated charges in efficient solar cells

Methods

Results

Conclusion