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 CH 3 NH 3 PbI 3 mixed with PC 61 BM ([6,6]‐phenyl‐C61‐butyric acid methyl ester), where CH 3 NH 3 PbI 3 acts as the electron donor and PC 61 BM 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 CH 3 NH 3 PbI 3 . The BHJ pero‐HSCs are further optimized by using PC 61 BM/TiO 2 bi‐electron‐extraction‐layer (EEL), which are both solution‐processed and then followed with low‐temperature thermal annealing. Due to higher electrical conductivity of PC 61 BM over that of TiO 2 , an efficiency of 14.98%, the highest reported efficiency for the pero‐HSCs without incorporating high‐temperature‐processed mesoporous TiO 2 and Al 2 O 3 as the EEL and insulating scaffold, is observed from PC 61 BM modified BHJ pero‐HSCs. Thus, the findings provide a simple way to approach high efficiency low‐cost pero‐HSCs.