Improving Ultraviolet Stability of Perovskite Solar Cells via Singlet Fission <scp>Down‐Conversion</scp><sup>†</sup>
Yanda Zhang, Shuqin Xiao, Wangping Sheng, Jia Yang, Licheng Tan, Yiwang Chen
Abstract
Comprehensive Summary The instability of perovskite materials under continuous ultraviolet (UV) light irradiation and high sensitivity in humid environments remain obstacles to future commercialization. Especially, the photovoltaic performance of perovskite solar cells (PVSCs) is prone to decline under UV light exposure for sustained periods of time. However, in conventional methods, preventing UV light from entering PVSCs usually comes at the expense of reducing short circuit photocurrent ( J sc ). Herein, the UV stability of PVSCs is modified by introducing a singlet fission down‐conversion layer 6,13‐bis(triisopropylsilylethynyl) pentacene (TIPS‐PEN) via one‐step anti‐solvent method without sacrificing device efficiency. The introduction of down conversion layer can not only improve the J sc by converting UV light into multiple excitons, but also enhance the open‐circuit voltage ( V oc ) owing to a better matched energy level alignment at the perovskite/spiro‐OMeTAD interface. Consequently, the TIPS‐PEN incorporated PVSCs attain the champion power conversion efficiency (PCE) up to 22.92% accompanied with dramatically increased UV photostability which can retain 80% of its primitive PCE under continuous UV light soaking for 150 h. Moreover, the unencapsulated PVSCs with TIPS‐PEN exhibit remarkable moisture stability which can sustain over 80% of the initial value under air conditions (50% relative humidity, 25 °C) after 1000 h.