This article investigates the effect of an external electric field on the photoluminescence (PL) of a methylammonium lead iodide (MAPbI3) film in a working solar cell architecture. Our study reveals hysteretic PL intensity responses when changing the voltage scanning direction, namely, PL-V hysteresis. The external electric field is found to have multiple effects on the photoexcited states of PSCs. First, an external electric field instantaneously changes the drift velocity of photogenerated charge carriers. Second, it drives ion migration and thus generates an induced electric field which screens the external field. Third, the ion migration driven by the external electric field also changes the distribution and density of charge traps that are responsible for nonradiative recombination. The first effect leads to instant PL change which is not responsible for PL-V hysteresis, while the other two effects are closely related to the slow kinetics of ion migration and lead to the PL-V hysteresis in perovskite solar cells.
Bibliographical noteFunding Information:
This work is supported by the Grant-in-Aid program of the University of Minnesota. Research was carried out in part at the Center for Functional Nanomaterials, Brookhaven National Laboratory, which is supported by the U.S. Department of Energy, Office of Basic Energy Sciences, under Contract DESC0012704. Use of the Center for Nanoscale Materials, an Office of Science user facility, was supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract DE-AC02-06CH11357. This project was supported in part by the U.S. Department of Energy, Office of Science, Office of Workforce Development for Teachers and Scientists (WDTS) under the Visiting Faculty Program (VFP). The authors would like to thank Dr. Mircea Cotlet, Dr. Chang-Yong Nam, Dr. Seth Darling, and Dr. David Gosztola for their technical support for solar cell fabrication and characterizations.
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