Tuning the Optoelectronic Properties of Iminodibenzyl-Triphenylamine Based Semiconductors: Hybrid Self-Powered Photodetector Applications

Abstract

Here, electron-rich organic semiconductors (IDB-TPA 1 and IDB-TPA 2) were designed by integrating the iminodibenzyl (ID) core with triphenylamine (TPA) units to achieve efficient charge distribution and tunable optoelectronic properties. The compounds were synthesized starting from iminodibenzyl core via successive bromination, N-alkylation, and Suzuki coupling reactions, and their structures were characterized by 1H NMR, 13C NMR, FTIR, and mass spectrometry. In addition, a comprehensive theoretical investigation of the IDB-TPA derivatives was performed using DFT and TD-DFT methods to elucidate their electronic structures and excited-state behavior. Furthermore, ıt was examined the performance of hybrid heterojunction (HJ) self-driven photodetectors based on IDB–TPA 1/n-Si and IDB–TPA 2/n-Si (referred to as D1 and D2, respectively). Beyond varying white light intensities (10–150 mW/cm²), the device performance was analyzed under UV, yellow, and IR illumination at a constant power density of 8 mW/cm2. The D1 and D2 HJs exhibited remarkable optoelectronic characteristics; at a reverse bias of -2.0 V, the responsivity (R) values reached 726 mA/W (at 365 nm) and 904 mA/W (at 590 nm), respectively. Furthermore, optimum detectivity (D) values were calculated as 3×10¹² and 4.3×1011 Jones for D1 and D2, respectively. A significant external quantum efficiency (EQE) of 312% was achieved for D2 at 365 nm, indicating an internal gain mechanism within the hybrid interface. Notably, the devices demonstrated an exceptional on/off ratio of 8.12×105 at zero bias under 590 nm illumination, highlighting their immense potential for high-contrast, self-powered broadband sensing applications.