Interface modification effect on the performance of Cs_xFA_1-xPbI_yBr_3-y perovskite solar cells fabricated by...

In this study, high quality Cs_xFA_1-xPbI_yBr_3-y perovskite thin films were successfully fabricated by an evaporation/spray-coating hybrid deposition method. In this method, CsI and PbI₂ were first deposited via thermal evaporation, and then FAI/FABr mixed solution was sprayed on the CsI/PbI₂ substrate to form the Cs_xFA_1-xPbI_yBr_3-y film. As confirmed by x-ray diffraction, scanning electron microscopy, and atomic force microscopy, a perovskite film with full surface coverage and small surface roughness was obtained. Then, the effect of interface modification materials on the performance of perovskite solar cells (PSCs) was investigated: the devices with the [6,6]-phenyl-C₆₁-butyric acid methyl ester (PCBM) interlayer incorporated via vacuum evaporation deposition between SnO₂ and perovskite showed remarkably higher performance than those with the C₆₀ interlayer, which was attributed to enhanced charge extraction and reduced recombination at the SnO₂/PCBM/perovskite interface. As a result, a high power conversion efficiency (PCE) of 18.21% was obtained for the 0.16 cm² device. To the best of our knowledge, it is the highest efficiency of Cs_xFA_1-xPbI_yBr_3-y based PSCs fabricated by the spray technique. Furthermore, we fabricated mini-modules with the size of 5 × 5 cm² and achieved a PCE of 14.7%.