Self-powered high-performance ultraviolet C photodetector based on poly(9-vinyl carbazole)/SnO2 quantum dot heterojunction

Ultraviolet C (UVC) photodetectors have attracted significant attention recently owing to the importance of UVC detection for preventing human skin damage, monitoring environmental conditions, detecting power facility aging, and military applications. The “solar-blindness” of UVC detectors ensures low noise levels, benefiting from lower interference than other environmental signals. In this study, a solution-processed PN heterojunction consisting of P-type polymer (poly(9-vinyl carbazole) (PVK)) and N-type metal oxide quantum dots (SnO2 QDs) was used to develop a self-powered high-performance UVC photodetector. Reducing the size of the SnO2 QDs significantly enhanced the selective absorption of the UVC wavelength range via quantum confinement. The device architecture and constituent film thickness were carefully controlled to enhance the performance of the PVK/SnO2 QD UVC photodetector. Under the optimized conditions, the device exhibited remarkable responsivity (49.6 mA W−1 at 254 nm and 166 mA W−1 at 220 nm), detectivity (2.16 × 1010 Jones at 254 nm), UVC/ultraviolet A (UVA) rejection ratio (R254 nm/R365 nm and R220 nm/R365 nm of ~260 and 880, respectively), and stability over long-term self-powered on/off operations. Our solar-blind UVC photodetector can be used to inexpensively, simply, and precisely monitor hazardous UVC light in various applications.