Self-powered broadband photodetector with intelligent sensing based on a mixed-dimensional TiS3/WSe2 van der Waals heterojunction

Broadband, high-efficiency, and low-power multifunctional integrated photodetectors are essential for advanced applications, including imaging, optical communication, and remote sensing. Photodetectors based solely on two-dimensional materials still encounter challenges such as limited out-of-plane charge transport, relatively low in-plane carrier mobility, and inadequate photocurrent generation. Here, we report a mixed-dimensional TiS3/WSe2 van der Waals heterojunction photodetector with type-II band alignment, enabling efficient carrier separation. The device achieves broadband detection from 405 to 1050 nm, with a responsivity of 1.61 A/W, an external quantum efficiency of 261.21%, and a specific detectivity of 2.31 × 1011 Jones under a bias voltage of 1 V. Under zero bias, the device exhibits a responsivity of 52 mA/W, a specific detectivity of 1.19 × 1011 Jones, and an open-circuit voltage of 145 mV. Furthermore, integrated with a convolutional neural network, the TiS3/WSe2 photodetector enables handwritten digit recognition accuracies of up to 97.0% under biased operation and 88.7% under self-powered sensing conditions. These results establish the TiS3/WSe2 heterojunction as a promising platform for broadband, low-power, and self-powered intelligent optoelectronics.