Recent progress of organohalide perovskite solar cells

Abstract

Since 2009, greater attention has been paid to organic-inorganic hybrid CH3NH3PbI3 solar cells because of their simple fabrication process and high power conversion efficiency. Organohalide perovskite solar cells now develop very fast and their photovoltaic performance has been gradually improved. However, because of a band-gap limitation, the sunlight absorption spectrum of CH3NH3PbI3 is not broad enough to produce enhanced photovoltaic properties. In addition, Pb, as an important element, is toxic in organohalide perovskite. Thus, it is significant and meaningful to fabricate narrow-gap, environmentally friendly organohalide perovskite solar cells with better chemical stability. In the present paper, we mainly reviewed the progress in the band-gap engineering of perovskite materials to identify elements to replace toxic Pb and improve the absorption efficiency of incident light and the photovoltaic performance of solar cells. The influences of organic and inorganic hole transporting materials on the power conversion efficiencies of devices were compared, followed by a discussion of the recent progress in hole-conductor-free solar cells. To date, the theoretical research on organohalide perovskites is neither fully comprehensive nor far-reaching. We then conducted a review of the progress of theoretical research on the atomic structure, band structure, and band gap of CH3NH3PbI3 and other analog perovskite materials. The advantages and disadvantages of popular theoretical methods and their issues, which would be helpful for developing computational work, are also discussed. Finally, we include a number of open questions relevant to this field and present some research topics for the future.