Abstract
Organic-inorganic hybrid perovskites exhibiting exceptional photovoltaic and optoelectronic properties are of fundamental and practical interest, owing to their tunability and low manufacturing cost. For practical applications, however, challenges such as material instability and the photocurrent hysteresis occurring in perovskite solar cells under light exposure need to be understood and addressed. While extensive investigations have suggested that ion migration is a plausible origin of these detrimental effects, detailed understanding of the ion migration pathways remains elusive. Here, we report the characterization of photo-induced ion migration in perovskites using in situ laser illumination inside a scanning electron microscope, coupled with secondary electron imaging, energy-dispersive X-ray spectroscopy and cathodoluminescence with varying primary electron energies. Using methylammonium lead iodide and formamidinium lead iodide as model systems, we observed photo-induced long-range migration of halide ions over hundreds of micrometers and elucidated the transport pathways of various ions both near the surface and inside the bulk of the samples, including a surprising finding of the vertical migration of lead ions. Our study provides insights into ion migration processes in perovskites that can aid perovskite material design and processing in future applications.
| Original language | English |
|---|---|
| Article number | 1846 |
| Journal | Nature Communications |
| Volume | 14 |
| Issue number | 1 |
| DOIs | |
| State | Published - Dec 2023 |
Funding
The work conducted at University of California Santa Barbara (SEI and EDS) was based on research supported by US Department of Energy, Office of Basic Energy Sciences, under the award number DE-SC0019244 (for the development of the laser-coupled SEM) and by the US Army Research Office under the award number W911NF-19-1-0060 (for studying photo-induced physics in emerging materials). T.K. also acknowledges the support of the new faculty startup fund from Seoul National University and the Institute of Advanced Machines and Design at Seoul National University (SNU-IAMD). Cathodoluminescence microscopies were supported by the Center for Nanophase Materials Sciences (CNMS), which is a US Department of Energy, Office of Science User Facility at Oak Ridge National Laboratory. The sample fabrication at National Renewable Energy Laboratory (NREL) was supported by the US Department of Energy under Contract No. DE-AC36-08GO28308 with Alliance for Sustainable Energy, Limited Liability Company (LLC), the Manager and Operator of NREL. The authors at NREL also acknowledge the support on perovskite sample preparation from DE-FOA-0002064 and DE-EE0008790, funded by the US Department of Energy, Office of Energy Efficiency and Renewable Energy, Solar Energy Technologies Office. The views expressed in the article do not necessarily represent the views of the DOE or the U.S. Government.