Preparation of ZnO electron transport layers by spray technology for perovskite solar cells

• ZnO and CuI films were deposited by spray method under low temperature.
• The surface morphology of ZnO films impacts on the coverage rate of perovskite.
• PSCs based on FTO/ZnO/CH3NH3PbI3/CuI/Au reached a champion PCE of 3.47%.

ZnO-based electron transport layers (ETLs) have caused wide public interest in flexible and wearable electronic devices owing to its higher electron mobility and crystalline without sintering processes. Here we describe a fast, inexpensive and low temperature spray method for the preparation of ZnO electron transport layers in CH3NH3PbI3-sensitized perovskite solar cells (PSCs) based on CuI holes transporter layers (HTL). The SEM results show that the surface morphology of ZnO films has an impact on the coverage rate of perovskite which is caused by the spray method. Optimization of the thickness of ZnO layers yielded highest power conversion efficiency of devices up to 3.47% with short-circuit current density Jsc, open-circuit voltage Voc and fill factor were 14.21 mA/cm2, 0.55 V and 44%, resp