In Sn-based halide perovskite solar cells (PSCs), the oxidation of Sn 2+ to Sn 4+ under ambient air leads to unwanted p-type doping in the perovskite film, which is a main reason for increased background carrier density and low efficiency. Here, we find that the introduction of bromide into formamidinium tin iodide (CH(NH 2 ) 2 SnI 3 , FASnI 3 ) lattice significantly lowers the carrier density of perovskite absorber, which is thought to be a result of reduction of Sn vacancies. It reduces the leakage current of devices, increases recombination lifetime, and finally improves open-circuit voltage and fill factor of the resulting devices employing mesoporous TiO 2 as an electron transport layer. Consequently, a high power conversion efficiency (PCE) of 5.5% is achieved with an average PCE of 5%, and after encapsulation the devices are highly stable over 1000 h under continuous one sun illumination including the ultraviolet region. This study suggests a simple approach for improving stability and efficiency in FASnI 3 -based PSCs.
ASJC Scopus subject areas
- Chemistry (miscellaneous)
- Renewable Energy, Sustainability and the Environment
- Fuel Technology
- Energy Engineering and Power Technology
- Materials Chemistry