CdSe-based quantum dots assisted deep ultraviolet light detection and visualization

To clarify the positive effect of the down-conversion process for ultraviolet (UV) and deep ultraviolet (DUV) light detection and visualization, we choose, synthesize, and characterize a spectrum of direct-bandgap CdSe-based colloidal quantum dot (QD) solvents and color-conversion layers (CCLs) across blue, green, yellow, orange, and red hues. Their optical absorption, emission, and response speeds under various UV and DUV wavelength of 280 nm, 372 nm, and 405 nm are evaluated. The blue QD CCL demonstrated the highest quantum yield up to 0.68. By integrating this blue QD CCL directly onto a silicon-based photodiode, the responded optical power to 280-nm DUV light is significantly enhanced by 27 times; this data decreases slightly to 23 times when using orange QDs, due to the comparatively lower quantum yield. For the optimal result in a communication system, the orange QDs help exhibit the highest response of 520 mV when stimulated with 372-nm UV light, compared with a substantial improvement over the original response of 120 mV. This enhancement makes the orange QDs significantly reduces the BER, especially at data rates below 70 Mb/s, due to the stronger response of the avalanche photodiode (APD) at 600 nm. Furthermore, to demonstrate the potential application of QDs for patterning and visualization, we have also produced CdSe-based QDs through inkjet printing, showcasing their printability, high stability in air, and pure color emission under DUV illumination. These results underscore the significant potential of CdSe-based QDs for full-color anti-counterfeiting solutions and their integration into flexible, printable wearables for a variety of visualization and DUV detection applications.