Naphthalene imide dimer as interface engineering material: An efficient strategy for achieving high-performance perovskite solar cells

How to design and synthesize interfacial engineered materials that have efficient surface passivation and electron extraction properties is an important problem in the field of optoelectronic materials. Herein, a simple naphthalene imide dimer, namely 2FBT2NDI, is developed by Stille coupling reaction with a high yield, and it is used as interface engineering material for inverted perovskite solar cells (PSCs). Owing to the existence of intermolecular interactions between MAPbI₃ and the 2FBT2NDI layer, the introduction of the interfacial layer can passivate the surface defects of perovskite film and improve interface contact. In addition, 2FBT2NDI exhibits suitable energy levels and high electron mobility because of its large linear conjugated skeleton containing two fluorine atoms, which are beneficial for electron extraction for efficient PSCs. By employing 2FBT2NDI as an interfacial layer, inverted PSCs show a maximum power conversion efficiency of 20.1%, which is over 14% higher than that of the control devices without interfacial layer (17.1%). These results highlight that the naphthalene imide dimer can potentially be used as a commercializable interfacial material for achieving high-performance PSCs.