Sulfurized Colloidal Quantum Dot/Tungsten Disulfide Multi‐Dimensional Heterojunction for an Efficient Self‐Powered Visible‐to‐SWIR Photodetector

Abstract Emerging semiconducting materials show considerable promise for application in the development of next‐generation optoelectronic devices. In particular, broadband light detection is crucial in various applications, including multispectral imaging and cognition. Therefore, tuning the physical properties of semiconductors and thereby building an efficient heterojunction are important for achieving a high‐performance photodetection device. In this study, a heavy p‐type colloidal quantum dot (CQD) is synthesized through solution‐based sulfurization. The resulting cubic‐shaped CQD exhibits broadband and strong absorption, which enable its broadband absorption. Further, a multidimensional 0D‐2D heterojunction is developed using p‐type CQD and n‐type tungsten disulfide (WS 2 ). This efficient p‐n junction is operated as a fully self‐powered optical sensor and phototransistor under various light illumination conditions. Under the self‐powered condition, the CQD/WS 2 heterojunction device exhibits 440‐ and 200‐fold‐higher responsivity and detectivity, respectively, than pristine WS 2 .