Perovskite-polymer hybrid solar cells with near-infrared external quantum efficiency over 40%

In the past several years, conjugated polymers and organometal halide perovskites have become regarded as promising light-absorbing materials for next-generation photovoltaic devices and have attracted a great deal of interest. As the main part of this contribution, we describe the enhancement of near-infrared (NIR) photoresponse of well-known CH3NH3PbI3-xClx-based solar cells by the integration of bulk heterojunction (BHJ) small band gap polymer: fullerene absorbers. Particularly, the integration of a commercially available polymer PDPP3T and PCBM-based BHJ boosts the peak external quantum efficiency (EQE) by up to 46% in the NIR region (800-1000 nm), which is outside of the photoresponsive region (300-800 nm) of conventional perovskite solar cells. This substantial improvement in the EQE over the NIR region offers an additional current density of similar to 5 mA cm(-2) for the control perovskite solar cell, and a high power conversion efficiency (PCE) of over 12% was obtained in the perovskite/BHJ-based solar cells. In addition, the insertion of the BHJ absorber consisting of a small band gap polymer PDTP-DFBT and PCBM also results in nearly 40% EQE for the perovskite/BHJ solar cell. The results also reveal that controlling over the polymer/PCBM weight ratio for a BHJ absorber is the key to achieving the optimal efficiency for this type of perovskite-polymer hybrid solar cell.