White Light-Emitting Diodes Based on AgInS₂/ZnS Quantum Dots with Improved Bandwidth in Visible Light Communication.

Cheng Ruan,Xiongbin Chen,Changyin Ji,Hongda Chen,Vicki L Colvin,Yu Zhang,Chun Sun,William W Yu,Min Lu

doi:10.3390/nano6010013

Abstract

Quantum dot white light-emitting diodes (QD-WLEDs) were fabricated from green- and red-emitting AgInS2/ZnS core/shell QDs coated on GaN LEDs. Their electroluminescence (EL) spectra were measured at different currents, ranging from 50 mA to 400 mA, and showed good color stability. The modulation bandwidth of previously prepared QD-WLEDs was confirmed to be much wider than that of YAG:Ce phosphor-based WLEDs. These results indicate that the AgInS2/ZnS core/shell QDs are good color-converting materials for WLEDs and they are capable in visible light communication (VLC).

Highlights

With the increasing concerns in global climate change and environmental protection, people are looking for alternatives to reduce energy consumption and greenhouse gas emission [1,2]
Green- and red-emitting AgInS2 /ZnS core/shell Quantum dots (QDs) were dissolved in hexane, and UV glue was added dropwise into each of the QD solutions
The two QD/UV glue mixtures were respectively dropped onto the blue LED chips layer by layer, and each layer was baked for 1 min under 365 nm ultraviolet light irradiation to harden the liquid on the LED chips

Summary

Introduction

With the increasing concerns in global climate change and environmental protection, people are looking for alternatives to reduce energy consumption and greenhouse gas emission [1,2]. The rare-earth phosphors represented by YAG:Ce3+ are prevalent in fabricating commercial WLEDs [6,7]. Their color rendering is poor due to the lacking of red emission in the visible spectrum [2,8]. AgInS2 /ZnS core/shell QDs were investigated as desirable nontoxic substitutes [27,28,29] Their photoluminescence (PL) wavelength can be adjusted from 520 nm to 680 nm with large Stokes shifts [30,31]. The PL lifetime of AgInS2 QDs was much shorter than that of the YAG:Ce3+ phosphor [32,33], and the corresponding modulation bandwidth was wider, making them ideal for improving system communication performance in visible light communication (VLC)

Materials

Characterizations

Conclusions