Modifying buried interface via 6-aminonicotinic acid molecule dipolar layer for efficient and stable inorganic perovskite solar cells

Abstract

The buried electron-transport layer (ETL)/perovskite interface not only influences the interface charge transport but also directly affects the perovskite crystallization, and thereby is crucial for the efficiency promotion of inorganic CsPbX₃ perovskite solar cells (PSCs). Herein, 6-aminonicotinic acid (ANA) molecule is employed to modify the buried TiO₂ ETL/CsPbIBr₂ perovskite interface through forming a molecule dipolar layer. The formation of ANA molecule dipolar layer passivates the defects at the buried TiO₂ ETL/CsPbIBr₂ perovskite interface, ameliorates the interface contact, and optimizes the interface energy level alignment, which considerably enhances the electron extraction and transport at the buried interface. Meanwhile, the buried interface modified by ANA molecule dipolar layer facilitates fabricating the high-quality CsPbIBr₂ perovskite film. Benefiting from the above favorable features, the assembled carbon-based CsPbIBr₂ PSC achieves a power conversion efficiency of 10.98 %, which is among the highest efficiency of carbon-based CsPbIBr₂ devices reported previously. In addition, the construction of ANA molecule dipolar layer at the buried interface notably enhances the stability of CsPbIBr₂ perovskite and fabricated PSCs. Under ambient conditions, the unencapsulated CsPbIBr₂ device with ANA molecule dipolar layer maintains 90.1 % of its original efficiency after 45-day storage.