Reduced energy loss in SnO2/ZnO bilayer electron transport layer-based perovskite solar cells for achieving high efficiencies in outdoor/indoor environments

The energy loss in perovskite solar cells (PSCs) is a key factor that limits the full potential of photovoltaic performance to values below the Shockley-Queisser limit. Herein, we report a bilayer structure of the electron transport layer (ETL) for reducing energy loss in methylammonium lead triiodide (MAPbI(3))-based planar heterojunction PSCs. The controlled electronic structure of the bilayer ETL affords suitable energy band matching at the interface of the MAPbI(3)layer for electron transport/hole blocking, which effectively suppresses trap-assisted recombination at the interface of PSCs. As a result, the optimized bilayer ETL reduces charge recombination at the interfaces of the perovskite layer, boosting the power conversion efficiency (PCE) of the MAPbI(3)-based PSCs up to 20.43% with an open circuit voltage (V-OC) as high as 1.20 V under 1 sun conditions. In addition, the bilayer ETL-based devices retained a highV(OC)of 0.98 V under illumination from a white light emitting diode (1000 lux), realizing PCEs of up to 37.2% under indoor conditions with good ambient stability for >800 h. These findings suggest the importance and potential of the bilayer ETL for reduced energy loss to generate high power outputs in outdoor/indoor environments of PSCs.