Investigation of Al2O3 and ZrO2 spacer layers for fully printable and hole-conductor-free mesoscopic perovskite solar cells

Fully printable and hole-conductor-free mesoscopic perovskite solar cells (PSCs) were prepared with Al2O3 or ZrO2 spacer layer. Mesoscopic TiO2 and the spacer layer were used as the scaffold in the PSC. The PSC based on mesoporous ZrO2 spacer layer obtains the short-circuit current density (J(sc)) of 20.2 mA cm(-2) and photoelectric conversion efficiency (PCE) of 8.72%, which are 23.17% and 59.12% higher than those of PSCs based on mesoporous Al2O3 spacer layer, respectively. Comparing with Al2O3, the larger pores of ZrO2 spacer layer are favorable for the infiltration and crystallization of perovskite, generating large grains to reduce the crystal boundaries. Hence, ZrO2 possesses superior performance than Al2O3 as the spacer layer for PSCs. This study can provide a guide for the rational design of efficient spacer layers for high-performance and hole-conductor-free PSCs. (C) 2017 Elsevier B.V. All rights reserved.