Regulation of buried interface in perovskite solar cells by 1, 2-PDADI molecular materials

SnO 2 has attracted significant attention as a potential replacement for TiO 2 in perovskite solar cells (PSCs) due to its high optical transmittance, stable physicochemical properties, and ability to process at low temperatures. However, when an SnO 2 electron-transport layer is prepared using solution gel spin coating, many oxygen vacancy defects are generated in the SnO 2 bulk and on its surface. These defects may result in nonradiative recombination at the SnO 2 /perovskite interface. This study proposes a novel and effective multibottom interfacial modification strategy that introduces 1,2-propanediamine hydroiodic acid (1,2-PDADI) molecules with multiple functional groups at the SnO 2 /perovskite interface. The incorporation of 1,2-PDADI molecules effectively passivates the oxygen vacancy defects at the SnO 2 surface and considerably improves the electronic properties of SnO 2 by reducing nonradiative recombination. Additionally, the interaction between the –NH 3 group in 1,2-PDADI and PbI 2 substantially reduces the PbI 2 content, thereby inhibiting defects forming in perovskite films. As a result, PSCs modified with 1,2-PDADI achieve a higher efficiency of 24.70% and demonstrate reduced hysteresis characteristics compared to the control (22.86 %). Thus, this study offers a cost-effective, straightforward, and effective approach for realizing high-efficiency PSCs.