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 CdS_xSe_1-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 CdS_xSe_1-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.