Heterocyclic Conjugated Polydentate Ligands Facilitate Interfacial Charge Transfer of Air‐Processed Carbon‐Based All Inorganic Perovskite Solar Cells with an Efficiency Over 15%

Modulating the charge transfer at the buried interface is crucial in carbon-based all-inorganic perovskite solar cells(C-PSCs). Nevertheless, most traditional organic modifiers present monofunctional and insulating characteristics which can impede charge transport potentially. Herein, a multifunctional heterocyclic conjugated polydentate modifier 4-imidazolylacrylic acid (UA) was proposed to modify buried interface. The results indicate that UA act as multifunctional roles due to its electron delocalization and polydentate feature, including increase the conductivity of tin oxide film, passivate interfacial defects, suppress recombination, enhance the energy level alignment, strengthen charge transport and eventually enable high performance C-PSCs prepared in air. Consequently, champion device present significant improvement in open circuit voltage (1.26 V), short circuit current density (15.69 mA cm^-2), and fill factor (79%) after UA modification, and the power conversion efficiency (PCE) increased from 11.91% to 15.56% compared to the control device. Furthermore, long-term stability of unencapsulated UA modified device maintains 80.59% of initial efficiency in glove box after 800 h and 82.86% of initial efficiency in air after 400 h, exhibiting better stability than the control device. This research offers an innovative idea to facilitate charge transfer in buried interface of C-PSCs via conjugated polydentate ligand modification.