ZnO-PCBM bilayers as electron transport layers in low-temperature processed perovskite solar cells

We investigate an electron transport bilayer fabricated at < 110 degrees C to form all low-temperature processed, thermally stable, efficient perovskite solar cells with negligible hysteresis. The components of the bilayer create a symbiosis that results in improved devices compared with either of the components being used in isolation. A sol-gel derived ZnO layer facilitates improved energy level alignment and enhanced charge Kcarrier extraction and a [6,6]-phenyl-C-61-butyric acid methyl ester (PCBM) layer to reduce hysteresis and enhance perovskite thermal stability. The creation of a bilayer structure allows materials that are inherently unsuitable to be in contact with the perovskite active layer to be used in efficient devices through simple surface modification strategies. (C) 2018 Science China Press. Published by Elsevier B.V. and Science China Press. All rights reserved.