Additive strategy to regulate crystallization and charge carrier dynamics of CsBi3I10 towards efficient and stable thin film solar cells

Abstract

All-inorganic semiconductor CsBi3I10 (CBI) has recently been recognized as promising alternatives to lead-based light harvesting materials. However, poor film quality and high defects greatly limit its photovoltaic performance in solar cell applications. Here, a simple and effective multifunctional additive of lead thiocyanate (Pb(SCN)2) is doped into CBI for tailoring film morphology and optoelectronic properties. Synergistic effects of Pb2+ and pseudohalide SCN- enable fine regulation of CBI crystallization as well as defects passivation, resulting in the formation of high-quality thin film with desirable uniformity, negligible pinholes, high electrical conductivity and remarkable moisture tolerance. The additive Pb(SCN)2 can efficiently alleviate moisture-induced degradation mechanism by inhibiting the phase transition from CBI to Cs3Bi2I9. In addition, the resulting solar cells exhibit significantly enhanced carrier lifetime, reduced charge recombination and increased charge collection yield, leading to a record efficiency of 1.13 % for planar CBI-based thin film solar cells. This work suggests additive engineering is efficient to modulate film properties and solar cell performance, which could be generally applicable to fabricate other Bi-based thin film and optoelectronic devices.