Research progress on the stability of perovskite solar cells

In recent years, with the rapid development of new energy and industrial technologies, the solar cell industry has begun to receive considerable attention. Perovskite solar cells are regarded as the third-generation solar cells. As of April 2019, on the basis of the international certification, the maximum power conversion efficiency of perovskite solar cells is 24.2%, which is similar to the highest power conversion efficiency of silicon solar cells. Perovskite solar cells exhibit high power conversion efficiency, low cost, simple preparation, and diversity of structure, which makes them the leaders in next-generation thin-film photovoltaic devices. In this paper the development history of perovskite solar cells was reported; the perovskite crystal structure and device structure were discussed in detail; and a tolerance factor for obtaining a more stable perovskite structure was introduced. We then summarized the A-site, B-site, and X-site composition engineering, the one-step, two-step and other fabrication methods and morphology control methods of perovskite thin films that could stabilize the perovskite crystal structure, reduce the pollution and harm of lead in perovskite films, control the growth of perovskite film, and regulate the band gaps. In addition, the influencing factors on the stability of perovskite solar cells was also discuss; light stability, thermal stability, and humidity stability that are the main causes of the decomposition of perovskite crystals, resulting in a serious decrease in device performance owing to the phase transition and degradation. The biggest obstacle for the industrialization of perovskite solar cells is the stability. Finally a series of methods that can improve the stability of perovskite solar cells were analyzed. The main solutions to the current stability problems of perovskite solar cells include the development of more stable 2D/3D perovskite structures, the development of new additives to control the growth of grains using the interfacial medication methods, and the selection of suitable hole and electron transport materials with superior properties.