Light-activated photocurrent degradation and self-healing in perovskite solar cells.

Wanyi Nie,Aditya D Mohite,Muhammad A Alam,Hsinhan Tsai,Jacky Even,Jared J Crochet,Jean-Christophe Blancon,Gautam Gupta,Claudine Katan,Kannatassen Appavoo,Manish Chhowalla,Amanda J Neukirch,Matthew Y Sfeir,Sergei Tretiak

doi:10.1038/ncomms11574

Abstract

Solution-processed organometallic perovskite solar cells have emerged as one of the most promising thin-film photovoltaic technology. However, a key challenge is their lack of stability over prolonged solar irradiation. Few studies have investigated the effect of light soaking on hybrid perovskites and have attributed the degradation in the optoelectronic properties to photochemical or field-assisted ion migration. Here we show that the slow photocurrent degradation in thin-film photovoltaic devices is due to the formation of light-activated meta-stable deep-level trap states. However, the devices can self-heal completely by resting them in the dark for <1 min or the degradation can be completely prevented by operating the devices at 0 °C. We investigate several physical mechanisms to explain the microscopic origin for the formation of these trap states, among which the creation of small polaronic states involving localized cooperative lattice strain and molecular orientations emerges as a credible microscopic mechanism requiring further detailed studies.

Highlights

Solution-processed organometallic perovskite solar cells have emerged as one of the most promising thin-film photovoltaic technology
Organometallic halide perovskite solar cells are promising because of their high power conversion efficiency (PCE) up to 15–20% achieved for methyl ammonium lead iodine (MAPbI3, MA 1⁄4 CH3NH3) materials[1,2,3,4]
We demonstrate that the degradation of hybrid perovskite solar cell performance with constant solar illumination in crystalline large-grain-size perovskite solar cells is due to the degradation of the photocurrent, which, importantly, can rapidly (o1 min) recover in the dark to its original value

Summary

Introduction

Solution-processed organometallic perovskite solar cells have emerged as one of the most promising thin-film photovoltaic technology. Capacitance measurements on devices and time-resolved photoluminescence (PL) spectroscopy on thin films attribute the observed photocurrent degradation to the formation of light-activated meta-stable trap states, which over prolonged illumination (light soaking) leads to the accumulation of space charges.

Results

Conclusion