Progress on the Development of Inorganic Lead-Free Perovskite Solar Cells

Perovskite solar cells have undergone rapid development because of their high solar absorption efficiencies, long carrier lifetime and diffusion length, high tolerance to lattice defects, and tunable bandgaps. In the past few years, the solar energy conversion efficiency of the perovskite solar cells has increased to 22.1%. However, despite their promising prospects, as demonstrated by the laboratory-fabricated prototypes, lead toxicity and instability of perovskite solar cells severely impeded their industrialization and applications. Recently, inorganic lead-free perovskite solar cells (such as ABX3 and A(2)BB'X-6), which use Sn, Ge, Bi, Ag, and other metals as replacements for Pb, and Cs and Rb as replacements for methylamine, have been pursued as potential solutions for the toxicity and stability issues. This review highlights the recent research efforts in the development of inorganic lead-free perovskite solar cells and provides a perspective on future developments.