Revealing and reducing the possible recombination loss within TiO2 compact layer by incorporating MgO layer in perovskite solar cells

Here, we report an origin of loss in open circuit voltage (Vac) in perovskite solar cells due to the possible trap-assisted recombination within the widely used TiO2 compact layer (CL) and at its interface with FTO substrate. A thin layer (TL) of MgO was employed to investigate the recombination mechanism. MgO in place of TiO2 CL (50-60 nm) enhances V-oc of the cell significantly while the MgO layer coated on TiO2 CL (TiO2-MgO bilayer) does not change the V-oc much. In combination with open-circuit voltage decay (OCVD) measurements, we reveal that recombination at FTO/TiO2 interface is a major factor regulating the voltage and efficiency of TiO2-based perovskite solar cells. (C) 2016 Elsevier Ltd. All rights reserved.