Interface modification effect on the performance of CsxFA1-xPbIyBr3-y perovskite solar cells fabricated by evaporation/spray-coating method

In this study, high quality Cs(x)FA(1-x)PbI(y)Br(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(x)FA(1-x)PbI(y)Br(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-C-61-butyric acid methyl ester (PCBM) interlayer incorporated via vacuum evaporation deposition between SnO2 and perovskite showed remarkably higher performance than those with the C-60 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 cm(2) device. To the best of our knowledge, it is the highest efficiency of Cs(x)FA(1-x)PbI(y)Br(3-y) based PSCs fabricated by the spray technique. Furthermore, we fabricated mini-modules with the size of 5 x 5 cm(2) and achieved a PCE of 14.7%.