Enhancement of Photocurrent\nin TI/TI (Bi<sub>2</sub>Se<sub>3</sub>/Bi<sub>2</sub>Te<sub>2</sub>Se) Heterojunction Devices:\nAn Electronic and Optoelectronic Based Study

The\ndiverse and intriguing characteristics of the heterojunction\ncomposed of topological insulator materials have piqued deep curiosity\nin the field of research, playing a crucial role in the advancement\nof electronic and optoelectronic devices. As a consequence of their\ntopological surface states, topological insulators are increasingly\nbeing explored in devices due to their high mobility and broadband\nabsorption. This study emphasizes the structural, electrical, and\noptical properties of TIs Bi<sub>2</sub>Se<sub>3</sub> and Bi<sub>2</sub>Te<sub>2</sub>Se and their heterojunction (Bi<sub>2</sub>Se<sub>3</sub>/Bi<sub>2</sub>Te<sub>2</sub>Se) through first-principles\ncalculations using density functional theory (DFT), incorporating\nspin–orbit coupling (SOC), leading to the fabrication of photoresistor\nsensor. The fabricated devices demonstrate excellent photoresponse\nacross a broad UV–vis spectrum while maintaining a low dark\ncurrent and outstanding optoelectrical characteristics, with exceptional\ndetectivity and competitive responsivity, positioning them as promising\ncandidates for low-power, cost-effective optical detection and sensor\napplications.