Applied Surface Science, Vol.464, 700-707, 2019
Low temperature solution-derived TiO2-SnO2 bilayered electron transport layer for high performance perovskite solar cells
Planar lead halide perovskite solar cells have shown a promising application in the field of printable solar cells. However, high-performance planar perovskite solar cells typically need a high-temperature process to achieve crystallized titanium oxide films as the electron transport layers, which hinders their application in flexible plastic substrates. Here, we demonstrate a bilayered TiO2-SnO2 film as an excellent substitute for electron transport layer using a low temperature liquid phase method. The bilayered TiO2-SnO2 film exhibits efficient electron extraction and hole blocking ability even at a low processing temperature of 150 degrees C. The as-obtained solar cells exhibit a champion power conversion efficiency of 18.85% (V-oc = 1.100 V, J(sc) = 22.52 mA cm(-2) and FF = 0.761) under one sun illumination, which is much higher than the devices based on individual SnO2 or TiO2 electron transport layers. The higher electron extraction driving force at the SnO2/perovskite interface and the stronger hole blocking ability due to the defect-free physical contact at the TiO2/FTO interface are suggested to be the main reasons for the improved device performance.