Bandgap-engineered Zn–Mn co-doped In2S3 quantum dots for high-performance tunable white quantum dot light-emitting diodes (WQLEDs)

Abstract

In pursuing energy-efficient and environmentally friendly lighting technologies, white-light quantum dot diodes (WQLEDs) have stood out as a powerful alternative to conventional lighting technologies. In this work, heavy metal-free In₂S₃ quantum dots (QDs), Zn-doped In₂S₃ QDs (Zn:In₂S₃), Mn-doped In₂S₃ QDs (Mn:In₂S₃), and Zn, Mn co-doped In₂S₃ QDs (ZnMn:In₂S₃), were synthesized by a simple thermal injection method. The luminescence intensity of ZnMn:In₂S₃ was greatly increased by a factor of 39 compared to that of In₂S₃. The maximum quantum yield of ZnMn:In₂S₃ can reach 28.8%. In addition, the mechanism of the influence of the band gap on the luminescence intensity of QDs was also discussed using UV-vis absorption spectroscopy and optical bandgap analysis. This work further fabricated WQLEDs using the synthesized QDs. ZnMn:In₂S₃ QD-based WQLEDs exhibited white light emission with Commission Internationale de l’Eclairage coordinates (0.34, 0.29) as well as a low ratio of blue light emission (4.2%). Notably, the cool-to-warm tunable white light emission can be achieved by adjusting the input voltage of ZnMn:In₂S₃ QDs-based WQLEDs. Thus, the prepared ZnMn:In₂S₃ QD-based WQLEDs can significantly reduce the blue light hazard and offer a promising eco-friendly alternative to rare-earth-based phosphors for portable lighting and display technologies.