Simultaneous enhancement of efficiency and stability in wide-bandgap perovskite solar cells by quinoxaline-based cathode interlayers

초록

Perovskite solar cells (PSCs) have gained considerable interest owing to their low fabrication cost and outstanding optoelectronic properties. Wide-bandgap PSCs are particularly important for tandem applications, but their performance is limited by substantial open-circuit voltage (Voc) loss caused by unfavorable cathode interfacial energetics and poor stability at the charge-transport-layer/top-electrode interface. Here, we report three donor–acceptor quinoxaline-based small molecules as dipolar and robust cathode interlayers for efficient and stable wide-bandgap inverted PSCs. Incorporation of electron-donating triphenylamine and electron-withdrawing triphenylphosphine oxide units generates strong molecular dipoles that lower the cathode work function, improve energy-level alignment, and lead to favorable ohmic contact at the C60/Ag interface. These interlayers also exhibit high thermal robustness and enhanced hydrophobicity. Consequently, the optimized device achieves a Voc of 1.31 V and a power conversion efficiency of 20.7%, while retaining over 85% of the initial performance after 1000 h under dark ambient storage and over 80% after 500 h at 65 °C in ambient air.

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