Zr-Doped TiO2 Electron Transport Layer for Reduced Hysteresis and Highly Efficient Perovskite Solar Cells

Abstract

Zr-doped TiO2 electron transport layer for reduced hysteresis and highly efficient perovskite solar cells Chirag Saharan, Pawan S Rana* Department of Physics, Deenbandhu Chhotu Ram University of Science and Technology, Murthal, Sonepat, India, 131039 drpawansrana.phy@dcrustm.orgLarge number of defects in compact TiO2 (c-TiO2) layer hinders the power conversion efficiency (PCE) of hybrid perovskite solar cells (PSCs). Metal doping in c-TiO2 layer has been recognized as a successful approach for boosting the PCE of PSCs. In this work, different amount of Zr is added in c-TiO2 layer and its impact on the photovoltaic properties of methylammonium lead iodide (MAPbI3)-based PSCs is studied. Incorporation of Zr enhanced the charge carrier collection at TiO2/perovskite interface as well as conductivity of TiO2 layer. It is observed that Zr-doping has reduced the dark current significantly by suppressing the leakage path. Consequently, the PSCs with optimal Zr-doping (10 vol%) displays open-circuit voltage (V OC) of 1.076 V, short-circuit current density (J SC) of 23.57 mA cm-2, and PCE of 18.16% under one-sun illumination. From our fundamental study, we confirm that Zr doping in TiO2 is highly beneficial to reduce the hysteresis index (HI) as low as 6.8% in comparison to pristine TiO2 with large HI of 17.9% and it reduces the trap-state density as well as non-geminated recombination losses. Together, our findings will pave the way for engineering the energy level of electron transport layer and fabrication of highly efficient PSCs. Key Words: Hybrid perovskite solar cells; Zr-doping; band alignment, trap-state density, non-geminated recombination losses