Abstract:
Perovskite solar cells (PSCs) have attracted significant attention due to their higher
efficiencies and lower fabrication costs. But for the better performance of PSCs, a high quality electron transport layer (ETL) is crucial. Various ETLs have been employed and
among them Tin (IV) oxide (SnO2) has emerged as a promising candidate for electron
selective layer in PSCs due to its superior optical and electrical characteristics. However,
there is still improvement needed in terms of poor surface morphology and conductivities
of SnO2. When SnO2 is used in conjunction with absorber layer in ambient conditions,
stability, and charge carrier recombinations at SnO2/perovskite interface remains a serious
challenge as well. This study presents the doping of lanthanum (La III), a rare earth
element, into SnO2 ETLs to improve the quality and performance of the perovskite layer
deposited on top of ETL in ambient condition. With the optimized 4% La (III) doping,
SnO2 ETLs become more crystalline with lower parasitic light absorption and surface
morphology improves significantly. The improvement in morphology due to doping
facilitates larger crystal growth of perovskite in ambient environment. Moreover,
Photoluminescence reveals that with optimized level of doping, interfacial charge
recombinations are significantly mitigated ensuring smooth injection of electrons into
ETL because of superior perovskite film quality. The mixed-cation mixed-halide
perovskite film deposited on 4% La-doped ETL show better resistance towards moisture
ingress and will substantially contribute to develop long-life of planar PSCs.
