Efficient electron-blocking layer-free planar heterojunction perovskite solar cells with a high open-circuit voltage

Perovskite solar cells (PSCs) with a simple device structure are particularly attractive due to their low cost and convenient fabrication process. Herein, highly efficient, electron-blocking layer (EBL)-free planar heterojunction (PHJ) PSCs with a structure of ITO/CH3NH3PbI3/PCBM/Al were fabricated via low-temperature, solution-processed method. The power conversion efficiency (PCE) of over 11% was achieved in EBL-free PHJ-PSCs, which is closed to the value of PSC devices with the PEDOT:PSS as the EBL. It is impressed that the open-circuit voltage (V-oc) up to 1.06 V, an average value of 1.0 V for 43 devices, was obtained in EBL-free PHJ-PSCs. The electrochemical impedance spectroscopy (EIS) results suggested that the high PCE and Voc are attributed to the relatively large recombination resistance and low contact resistance in EBL-free PHJ-PSCs. The solution-processed, EBL-free PHJ structure paves a boulevard for fabricating high-efficiency and low-cost PSCs. (C) 2015 Elsevier B.V. All rights reserved.