Recent progress in lead-free perovskite (-like) solar cells

Organic-inorganic hybrid perovskite solar cells (SCs) have emerged as one of the most promising contenders to traditional silicon solar cells, due to their active layers outstanding photoelectric properties, such as appropriate direct bandgap, balanced high carrier mobility and long carrier diffusion length, the identified power conversion efficiency (PCE) has reached to 22.7%. But the toxic lead, a key component in the archetypical light harvesting material, is a large obstacle to commercialization. Herein, we reviewed the recent progress in lead-free perovskite (-like) SCs according to the valent difference of metal ions in absorber material, e.g., bivalent (Sn 2+ , Ge 2+ , Cu 2+ , Sr 2+ ), trivalent (Bi 3+ , Sb 3+ ), tetravalent (Sn 4+ ) and hybrid valent (e.g. Ag + and Bi 3+ ). Finally, we gave an outlook on the tactic to achieve high performance lead-free perovskite (-like) SCs.