Efficient Solution‐Processed Bulk Heterojunction Perovskite Hybrid Solar Cells

Efficient conventional bulk heterojunction (BHJ) perovskite hybrid solar cells (pero-HSCs) solution-processed from a composite of CH3NH3PbI3 mixed with PC61BM ([6,6]-phenyl-C61-butyric acid methyl ester), where CH3NH3PbI3 acts as the electron donor and PC61BM acts as the electron acceptor, are reported for the first time. The efficiency of 12.78% is twofold enhancement in comparison with the conventional planar heterojunction pero-HSCs (6.90%) fabricated by pristine CH3NH3PbI3. The BHJ pero-HSCs are further optimized by using PC61BM/TiO2 bi-electron-extraction-layer (EEL), which are both solution-processed and then followed with low-temperature thermal annealing. Due to higher electrical conductivity of PC61BM over that of TiO2, an efficiency of 14.98%, the highest reported efficiency for the pero-HSCs without incorporating high-temperature-processed mesoporous TiO2 and Al2O3 as the EEL and insulating scaffold, is observed from PC61BM modified BHJ pero-HSCs. Thus, the findings provide a simple way to approach high efficiency low-cost pero-HSCs.