High efficiency perovskite solar cells using a PCBM/ZnO double electron transport layer and a short air-aging step

Abstract

Solution processed CH3NH3PbIxCl3-x based planar heterojunction perovskite solar cells with power conversion efficiency (PCE) above 14% are reported. The devices benefit from a phenyl-C-61-butyric acid methyl ester (PCBM)/ZnO double electron transport layer (ETL) as well as a short air-aging step. The role of the additional ZnO ETL is studied by scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS) and secondary ions mass spectroscopy (SIMS). Apart from improving the energy level alignment, the ZnO layer blocks the reactions between the metal electrode and perovskite components, increasing the air stability of the device. A crucial step in our processing is a short air-aging step for the device, which significantly increases the device performance by reducing the recombination process. Since the ZnO nanoparticle layer requires no thermal annealing, the maximum temperature to fabricate the device can be kept below 100 degrees C, making this structure compatible with roll-to-roll processing on plastic films. (C) 2015 Elsevier B.V. All rights reserved.