Liquid Metal‐Exfoliated SnO₂‐Based Mixed‐Dimensional Heterostructures for Visible‐to‐Near‐Infrared Photodetection

Ultra‐thin 2D materials have gain significant attention for making next‐generation optoelectronic devices. Here, a large‐area heterojunction photodetector is fabricated using a liquid metal‐printed 2D SnO 2 layer transferred onto CdTe thin films. The resulting device demonstrates efficient broadband light sensing from visible to near‐infrared wavelengths, with enhanced detectivity and faster photo response. Significantly, the device shows a ≈10 5 ‐fold increase in current than the dark current level when illuminated with a 780 nm laser and achieves a specific detectivity of ≈10 12 Jones, nearly two orders of magnitude higher than that of a standalone CdTe device. Additionally, temperature‐dependent optoelectronic testing shows that the device maintains a stable response up to 140 °C and generates distinctive photocurrent at temperatures up to 80 °C, demonstrating its thermal stability. Through band structure analysis, DFT calculations, and photocurrent mapping, the formation of a p‐n junction is confirmed, which enhances carrier separation via the built‐in potential, significantly boosting photoresponse. These results highlight the potential of liquid metal‐derived 2D materials in heterostructure integration, paving the way for advanced optoelectronic applications.