Tuning Performance of Heterojunction Flexible Photodetectors by Energy Band Alignment Engineering

Exploring innovative constituents in one-dimensional (1D) nanomaterials and integrating them with two-dimensional (2D) van der Waals (vdW) materials are in high demand as a unique platform for discovering new physical phenomena and designing innovative interface-based devices. This work demonstrates for the first time a supersensitive flexible broadband photodetector based on a hybrid 1D/2D heterojunction that integrates the synergetic properties of a 1D CdSxSe1–x nanobelt and a 2D PbI2 flake and systematically investigates their stoichiometric-dependent photoelectric response. The fabricated hybrid 1D/2D heterojunction device significantly boosts the light current while suppressing the dark current to the pA scale, enabling a high responsivity of 105 A/W. The remarkable photoresponse performance is ascribed to efficient charge carrier transfer between the 1D CdSxSe1–x nanobelt and the 2D PbI2 flake resulting from energy band alignment engineering. Meanwhile, the proposed hybrid 1D/2D heterojunction can be fabricated with a flexible tape substrate.