HOMO Energy Level Modulation with Fluorinated Poly(aryl)amines for Wide-Bandgap Perovskite Solar Cells

Fluorination stands out as an effective strategy to narrow the energy gap between HTMs, such as Poly(aryl)amines (PTAA), and perovskite materials. We demonstrate the synthesis of six novel fluorinated PTAA derivatives and present innovative methods for introducing trifluoromethyl (CF₃) groups into PTAA structures. Our investigation, incorporating electrochemical and optical spectroscopy analyses, highlights the significant influence of both the position and quantity of fluorine atoms on PTAA's energy levels. Additionally, we demonstrate that fluorine atoms and CF₃ groups impact orbital level structures differently, advancing our understanding of PTAA's role in PSCs. Importantly, we have fabricated wide-bandgap PSCs with fill factors exceeding 80%, short-circuit current densities surpassing 17 mAcm^-2, and power conversion efficiencies exceeding 17%. Notably, this was achieved without implementing surface passivation, underscoring the potential for optimizing high-performance HTMs in PSCs.