Enhancement of Photocurrent in TI/TI (Bi₂Se₃/Bi₂Te₂Se) Heterojunction Devices: An Electronic and Optoelectronic Based Study

The diverse and intriguing characteristics of the heterojunction composed of topological insulator materials have piqued deep curiosity in the field of research, playing a crucial role in the advancement of electronic and optoelectronic devices. As a consequence of their topological surface states, topological insulators are increasingly being explored in devices due to their high mobility and broadband absorption. This study emphasizes the structural, electrical, and optical properties of TIs Bi 2 Se 3 and Bi 2 Te 2 Se and their heterojunction (Bi 2 Se 3 /Bi 2 Te 2 Se) through first-principles calculations using density functional theory (DFT), incorporating spin–orbit coupling (SOC), leading to the fabrication of photoresistor sensor. The fabricated devices demonstrate excellent photoresponse across a broad UV–vis spectrum while maintaining a low dark current and outstanding optoelectrical characteristics, with exceptional detectivity and competitive responsivity, positioning them as promising candidates for low-power, cost-effective optical detection and sensor applications.