Small Molecules Functionalized Zinc Oxide Interlayers for High Performance Low-Temperature Carbon-Based CsPbI2Br Perovskite Solar Cells

The charge recombination resulting from bulk defects and interfacial energy level mismatch hinders the improvement of the power conversion efficiency (PCE) and stability of carbon-based inorganic perovskite solar cells (C-IPSCs). Herein, a series of small molecules including ethylenediaminetetraacetic acid (EDTA) and its derivatives (EDTA-Na and EDTA-K) are studied to functionalize the zinc oxide (ZnO) interlayers at the SnO2/CsPbI2Br buried interface to boost the photovoltaic performance of low-temperature C-IPSCs. This strategy can simultaneously passivate defects in ZnO and perovskite films, adjust interfacial energy level alignment, and release interfacial tensile stress, thereby improving interfacial contact, inhibiting ion migration, alleviating charge recombination, and promoting electron transport. As a result, a maximum PCE of 13.94% with a negligible hysteresis effect is obtained, which is one of the best results reported for low-temperature CsPbI2Br C-IPSCs so far. Moreover, the optimized devices without encapsulation demonstrate greatly improved operational stability.

Automated summary

The use of small molecules, including ethylenediaminetetraacetic acid (EDTA) and its derivatives, to functionalize the zinc oxide (ZnO) interlayers at the SnO2/CsPbI2Br buried interface improves the photovoltaic performance of low-temperature carbon-based inorganic perovskite solar cells (C-IPSCs). This strategy simultaneously repairs defects in ZnO and perovskite films, adjusts interfacial energy level alignment, and enhances interfacial contact, inhibiting ion migration, reducing charge recombination, and promoting electron transport.