Verification and mitigation of ion migration in perovskite solar cells

Metal halide perovskite materials have shown versatile functionality for a variety of optoelectronic devices. Remarkable progress in device performance has been achieved for last few years. Their high performance in combination with low production cost puts the perovskite optoelectronics under serious consideration for possible commercialization. A fundamental question that remains unanswered is whether these materials can sustain their optoelectronic properties during harsh and prolonged operational conditions of the devices. A major concern stems from an unprecedented and unique feature of perovskite materials, which is migration of ionic species (or charged defects). Recent studies have indicated that the ion migration might be a limit factor for long-term operational stability of the devices. In this regard, herein we have reviewed important studies on discovery, quantification, and mitigation of the ion migration process in metal halide perovskite materials. A possible emerging application using the ion migration is also briefly introduced.