Faming Li1 Mingzhen Liu1

1, University of Electronic Science and Technology of China, Chengdu, , China

Perovskite solar cells have attracted great attentions recently due to its excellent photoelectric properties. Especially, the non-halide lead sources such as lead acetate and lead thiocyanate have shown their potentials to improve the film morphology and crystallization. However, the devices fabricated via the non-halide sources generally generate lower power conversion efficiencies (PCEs) comparing with the lead halide source. Herein, we introduce a novel non-halide lead source, lead formate (Pb(HCOO)2), interacting with CH3NH3I to synthesize the CH3NH3PbI3 perovskite film. We believe that two octahedral structures, [PbI6]4- and [PbI6-x(HCOO)x]4-, are present in the precursors via Pb(HCOO)2 according to the coordination chemistry and then the [PbI6-x(HCOO)x]4- decomposes into PbI2 crystals appearing in the grain boundaries which could greatly reduce the carrier recombination. The PSCs via the Pb(HCOO)2 source exhibited an optimal PCE of 18.4% for an active area of 0.09 cm2 and 14.9% for the large active area of 1.015 cm2 respectively. The unsealed large-area device remained above 85% of the original PCE after 300 hours under 10% relative humidity of the air. This is the best performance reported so far for the devices fabricated via the non-halide lead source. The performance of the large area devices and low purity lead source pave the way of industrial production.