Gradient‐Alloyed QDs/MoS 2 /WSe 2 0D/2D Heterostructures for Advanced Self‐Powered Dual‐Band Photodetection
Sheng Hu, Jiahao Zhou, Huakang Yang, Haotian Luo, Jincheng Cai, Hongnan Luo, Zuocheng Pu, Jun Liu, Zhaoqiang Zheng, Wei Gao, Xiao LiuABSTRACT
Gradient‐alloyed quantum dots (QDs) offer advantages over conventional core‐shell structures for optoelectronic applications owing to their strain‐relieved interfaces and tunable quasi‐type‐II band alignments. However, their use as interface‐engineering sensitizers for self‐powered 2D van der Waals heterojunction (HJ) photodetectors remains insufficiently understood, particularly regarding how graded band structures and carrier delocalization affect zero‐bias dual‐band operation. Here, we demonstrate a self‐powered 0D/2D hybrid photodetector in which gradient‐alloyed CdS@Zn x Cd 1‐x S@ZnS (CSZCSZS) QDs serve as a band‐engineered sensitizing layer for a MoS 2 /WSe 2 type‐II HJ. Benefiting from their strain‐relieved graded structure, quasi‐type‐II carrier delocalization, and strong short‐wavelength absorption, these QDs modulate interfacial energetics and enhance photovoltaic carrier extraction. The designed back‐to‐back type‐II band alignment enables efficient electron injection from QDs into MoS 2 and hole transfer from MoS 2 to WSe 2 , promoting carrier separation and suppressing recombination. The device exhibits dual‐band responsivity of 1138 mA/W at 405 nm and 132.4 mA/W at 808 nm, a fast response time of 67 µs, specific detectivity exceeding 6.62 × 10 12 Jones, and a photoelectric conversion efficiency of 8.1%. Proof‐of‐concept dual‐channel optical communication and single‐pixel imaging further validate this strategy for high‐performance multifunctional hybrid photodetectors.