Suppressing Charge Recombination and Ultraviolet Light Degradation of Perovskite Solar Cells Using Silicon Oxide Passivation

摘要

Organic-metal lead halide perovskite solar cells (PSCs) featuring low-cost and high efficiency have been recognized as promising photovoltaic devices, but their serious charge recombination and ultraviolet light irradiation instability limit their output efficiency and long-term operation. In this work, we have introduced silicon oxide as an interfacial modifier of the electron transporting layer in TiO2-based planar heterojunction PSCs. The incorporation of a silicon oxide modifier passivates the trap states of perovskite absorber and suppresses the charge recombination of PSCs. As a consequence, a competitive solar-to-electricity conversion efficiency of 18.0 % was achieved for the device fabricated with the silicon-oxide-modified TiO2 electron extraction layer, which is increased by 15 % compared with the PSC fabricated with pristine TiO2; this can be attributed to the significantly increased open-circuit voltage and photocurrent density. Furthermore, the ultraviolet light irradiation stability of PSCs is greatly improved, resulting from the low photocatalytic activity of the silicon-oxide-modified TiO2 electron transporting layer, as revealed by the photoelectrochemical oxidation of CH3NH2. This work represents a feasible step through interfacial engineering toward the realization of ultraviolet-light-stable and scalable PSCs.

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