High-performance self-powered UV-to-NIR imaging photodetector based on Bi₂Te₃ p-n homojunction

2D Bi₂Te₃ is an emerging semiconducting materials show considerable promise for application in the development of next-generation optoelectronic devices. Especially, broadband photodetection is crucial in various applications, including multispectral imaging and cognition. Therefore, tuning the physical properties of semiconductors and thereby building an efficient p-n homojunction are important for achieving a high-performance photodetection device. However, until now, it is still difficult to construct Bi₂Te₃ p-n homojunction. In this work, Sb-doped Bi₂Te₃ was synthesized via chemical vapor deposition, which exhibited typical p-type conduction behavior and a considerable hole mobility of 1.6 cm² V⁻¹ s⁻¹. Benefiting from the built-in electric field, the Bi₂Te₃ p-n homojunction displays an apparent rectification effect and an extremely low dark current of approximately 10⁻¹⁴ A. Under illumination, the p-n homojunction, serving as a photodiode, achieved a high power conversion efficiency of 4.65 % and an excellent responsivity of 802.9 A/W. Furthermore, taking advantage of the built-in electric field, the p-n homojunction exhibited broadband self-driving photodetection from 367 to 1550 nm with ultra-high detectivity (3.84 × 10¹³ Jones at 520 nm and 8.82 × 10¹¹ Jones at 1550 nm). This work provides an effective strategy for synthesizing p-type Bi₂Te₃ and emphasizes the pivotal role of homojunctions for high-performance broadband photodetectors.