Efficient, high yield perovskite/fullerene planar-heterojunction solar cells: Via one-step spin-coating processing

In this paper, we report the fabrication of high crystalline perovskite film planar-heterojunction solar cells by a facile one-step spin-coating technique with improved control of thermal annealing time and solution concentration. We used an indium-doped tin oxide glass/poly(3,4-ethylenedioxythiophene):poly(styrene-sulfonate) (PEDOT:PSS) substrate as the hole transport layer, a PHJ of CH₃NH₃PbI₃ perovskite fabricated by one-step spin-coating processing as the active layer and fullerene structure as the electron transport layer, a thin bathocuproine (BCP) film as an hole-blocking layer (HBL), and an aluminum (Al) layer as the negative electrode. The optimized device under AM 1.5 (100 mW cm^-2) radiation achieved a high efficiency of 12.21% with an open circuit voltage of 0.83 V and FF of 0.68. Meanwhile, the devices do not show obvious hysteresis photovoltaic response, which has been a fundamental bottleneck for perovskite devices. The effects of MAI concentration and annealing time on the solar cells were also discussed on the basis of experimental observations.