Triaryl Imidazoles as a Hole-Transporting Interfacial Modifying Layer for Inverted Perovskite Solar Cells

The integration of hole-transporting organic interfacial modifying layers (OIMLs) into perovskite solar cells (PSCs) has attracted significant interest due to their ability to improve performance and stability. However, the development of cost-effective and straightforward methods for synthesizing OIMLs remains underexplored. In this work, we present the design and synthesis of two novel bromoaryl-substituted, imidazole-derived OIMLs: 2,4,5-tris(4-bromophenyl)-1H-imidazole (TPIM-Br) and 4,5-bis(4-bromophenyl)-2-(5-bromothiophen-2-yl)-1H-imidazole (DPIM-TBr). We investigated the thermal, optical, and electrochemical properties of the molecules, confirming their potential as OIMLs in PSCs. The computed energy levels and electrostatic surface potentials (ESPs) of these molecules were examined to elucidate the charge distribution and electron density within TPIM-Br and DPIM-TBr. Comprehensive characterization demonstrated that incorporation of the OIMLs enabled more efficient charge extraction and improved perovskite crystallinity. The champion device yielded 25.85% power conversion efficiency for TPIM-Br, compared to the control's 23.32%. This work presents a strategy to enhance the performance of inverted PSCs by incorporating OIMLs, offering a promising pathway for future developments in PSC technology.