Solution-Processed CuInS₂-Based White QD-LEDs with Mixed Active Layer Architecture

Abstract

Colloidal quantum dots (QDs) are attractive candidates for future lighting technology. However, in contrast to display applications, the realization of balanced white lighting devices remains conceptually challenging. Here, we demonstrate two-component white light-emitting QD-LEDs with high color rendering indices (CRI) up to 78. The implementation of orange CuInS/ZnS (CIS/ZnS) QDs with a broad emission and high quantum yield together with blue ZnCdSe/ZnS QDs in a mixed approach allowed white light emission with low blue QD content. The devices reveal only a small color drift in a wide operation voltage range. The correlated color temperature (CCT) could be adjusted between 2200 and 7200 K (from warm white to cold white) by changing the volume ratio between orange and blue QDs (1:0.5 and 1:2).

Flexible quantum dot light-emitting diodes for next-generation displays

“…2o, p). [71][72][73][74] A critical drawback of I-III-VI QDs is their broad emission spectra (FWHM:~100 nm), which removes the major advantage of QDs (i.e., high color purity due to narrow spectra) in display applications. 75 …”

Optical Properties, Synthesis, and Potential Applications of Cu-Based Ternary or Quaternary Anisotropic Quantum Dots, Polytypic Nanocrystals, and Core/Shell Heterostructures

“…A range of Cu based QDs have been tested in these designs, including Mn doped CuInZnS [211], CuInS 2 /ZnS [79,212,213,214], CuInSe 2 /ZnS [28], CuInZnS/ZnS [215], and CuInGaS/ZnS [216]. In addition, mixed systems exist using CuInS 2 /ZnS and ZnCdSe/ZnS QDs [217] or CdZnS/ZnS [218] have also been reported. A common trend in these systems is the use of synthesis, which optimise for high PLQY systems, with the dominant approach synthetically being to produce a type band alignment using ZnS on the core, therefore, increasing the PLQY and the resistance to photobleaching.…”

“…White light LEDs are an important class of LEDs aiming to produce emission as close as possible to blackbody emission at ≈ 6000 K, and therefore simulate sunlight to act as a replacement for a range of lighting sources used at present, including Cu–Sn-In–S based QDs [209] (Figure 17). A number of various Cu based QDs have also been demonstrated as promising white light sources [151,152,203,204,205,206,208,210,211,217,219,220,221,222], either via the use of down converting [152,203,204,205,206,207,208,209,210,219,220,221] or electroluminescence [211,217,218] s. These devices are achieved by either combining a number of luminescent sources or via the use of a single broad emission sources. Cu based QDs are an excellent fit for this type of light source due to the inherent broadness of the QD emission relative to other QDs.…”

Impedance Spectroscopy: A Versatile Technique to Understand Solution‐Processed Optoelectronic Devices

“…In particular, these devices can be well adapted for flexible electronics. During the past years, the performance of solution‐processed devices has been greatly improved and some of them are now comparable with or exceeding the conventional thin film devices . For example, perovskite‐based solar cells have already achieved higher efficiency than that made of evaporated CuIn x Ga 1‐x Se 2 and cadmium telluride .…”