Bridging the buried interface with conjugated molecule for highly efficient carbon-based inorganic CsPbI2Br perovskite solar cells fabricated in air

Manipulating the buried interface of all-inorganic perovskite solar cells (PSCs) is essential to improve the performance of devices. However, the conventional modifiers of interface typically present insulating feature that can impede the transportation of carrier, leading to an inferior charge transport efficiency. Herein, we propose a conjugated molecule, 2,4-hexadienoic acid potassium salt, which can act as a bridge at the buried interface of device and improve the crystallization of perovskite film. Besides, this interfacial modifier also promotes larger and denser grains, passivating defects and suppress non-radiative recombination of buried interface. Simultaneously, the electrical performance of tin oxide film is enhanced and facilitate a better energy level alignment. Consequently, carbon electrodes-based PSCs (C-PSCs) are fabricated via a hot air-assisted method in air, and C-PSCs based on all-inorganic perovskite demonstrate significant enhancement of open circuit voltage (1.25 V) via conjugated molecule modification, and the power conversion efficiency (PCE) increase significantly from 10.86 % to 13.11 %. Moreover, unencapsulated target devices exhibit better stability than the control devices. This work offers a new idea to construct an interfacial bridge via conjugated molecule for efficient and stable C-PSCs fabricated in air.