Buried interface engineering based on dipolar molecule interlayer for enhancing photovoltaic performance of CsPbIBr<sub>2</sub> perovskite solar cells
Abstract
<p indent="0mm">The buried-interface properties of inorganic perovskite solar cells play a key role in determining the quality of the perovskite film and the charge transfer at the buried interface. Therefore, the structure optimization of buried interfaces through the buried interface engineering is an effective strategy to improve the efficiency and stability of inorganic perovskite solar cells. In this work, 6-amino nicotinic acid (ANA) molecules were employed to modify the buried interface of CsPbIBr<sub>2</sub> perovskite solar cells (TiO<sub>2</sub>/CsPbIBr<sub>2</sub> interface). ANA molecules are absorbed on the surface of the TiO<sub>2</sub> electron-transport layer through strong interactions between the ‒COOH group and TiO<sub>2</sub>, forming an ANA molecule dipolar interlayer at the buried interface of CsPbIBr<sub>2</sub> perovskite solar cells. The formation of ANA dipolar interlayer improves the surface wettability of the TiO<sub>2</sub> layer by CsPbIBr<sub>2</sub> precursor solution, promotes the uniform nucleation and growth of the CsPbIBr<sub>2</sub> perovskite, enhances the perovskite quality, and ameliorates the interface contact. Meanwhile, the formation of the ANA dipolar interlayer increases the work functions of the TiO<sub>2</sub> layer, leading to the formation of an optimized energy level structure for electron transport at the buried interface between the TiO<sub>2</sub> layer and CsPbIBr<sub>2</sub> perovskite. Consequently, the assembled carbon-based CsPbIBr<sub>2</sub> perovskite solar cells without hole-transport layer achieve a high power conversion efficiency of 10.98%, which is 37% higher than the efficiency of the control device. In addition, the CsPbIBr<sub>2</sub> perovskite solar cell with ANA dipolar interlayer shows a superior stability. After 45 d of storage under ambient conditions, the unencapsulated device preserved over 90% of its initial efficiency.</p>
