Triarylamine-BODIPYs exhibiting record hole mobility: synthesis, photophysical, electrochemical, spectroelectrochemical, and charge carrier mobility studies

Abstract

High charge carrier mobility organic semiconductors (OSCs) are crucial for advancing next-generation electronic and optoelectronic technologies. Boron-dipyrromethene (BODIPY) based small molecules have demonstrated promising space-charge-limited current (SCLC) mobilities approaching ~10−3 cm2 V−1 s−1. In this work, we report triarylamine-functionalized BODIPYs BTA1–BTA4 synthesized via Pd-catalyzed Suzuki cross-coupling. The photophysical, electrochemical, spectroelectrochemical, computational, and charge carrier mobility studies of the BODIPYs were thoroughly investigated. BTA1–BTA4 exhibit an absorption band around 497 nm corresponding to π–π* transition of the BODIPY unit and a red-shifted broad shoulder corresponding to the intramolecular charge transfer (ICT). The electrochemical studies were performed to estimate the frontier molecular orbitals (FMO) energy level of triarylamine-BODIPYs. The spectroelectrochemical analysis of BTA1–BTA4 reveals new peaks in the near-infrared (NIR) region beyond 1000 nm. Charge carrier mobilities of compounds were explored by the SCLC technique at room temperature. The compounds BTA2–BTA4 exhibit high hole mobilities on the order of 10−2 cm2 V−1 s−1. These values are among the highest reported for BODIPY-based small molecules, demonstrating their potential for use in next-generation optoelectronics.