Bidirectional Bonding Interfacial Engineering Enables High-Performance Sb2S3/HgS Heterojunction Photodetector for Intelligent Healthcare Applications
Self-powered broadband photodetectors are pivotal for next-generation intelligent healthcare. Solution-processed mercury sulfide (HgS) is an attractive near-infrared absorber but is limited by interfacial instability, high defects, and sluggish response. Inspired by sulfur-mediated adhesion in Alhagi sparsifolia, a bioinspired interfacial engineering strategy employs an antimony sulfide (Sb2S3) interlayer to construct a bidirectional chemical bonding network. The Sb2S3 interlayer simultaneously forms Sb–O bonds with fluorine-doped tin oxide (FTO) substrates and Sb–S/Hg–S bonds with the HgS layer, thereby reinforcing interfacial adhesion, passivating coordination-unsaturated defect states, and establishing a type-II heterojunction with a strong built-in electric field. The resulting Sb2S3/HgS photodetector exhibits self-powered operation, broadband sensitivity spanning the visible to near-infrared region (642–1550 nm), an ultrafast response time of 2.47 ms, a detectivity up to 1.7 × 10^11 Jones, and retaining nearly constant photocurrent over 5000 continuous on-off switching cycles as well as prolonged air exposure. Beyond device-level performance, we demonstrate its utility in intelligent healthcare scenarios, including machine-learning-assisted liquid drug identification, binary-coded optical wireless communication, and high-fidelity photoplethysmography monitoring. This work establishes biomimetic bidirectional bonding as a generalizable paradigm for stabilizing solution-processed chalcogenide optoelectronics and accelerates the integration of self-powered broadband photodetectors into intelligent healthcare systems.