Quantum‐Dot Light‐Emitting Diodes for Large‐Area Displays: Towards the Dawn of Commercialization

Abstract

Quantum dots are a unique class of emitters with size-tunable emission wavelengths, saturated emission colors, near-unity luminance efficiency, inherent photo- and thermal- stability and excellent solution processability. Quantum dots have been used as down-converters for back-lighting in liquid-crystal displays to improve color gamut, leading to the booming of quantum-dot televisions in consumer market. In the past few years, efficiency and lifetime of electroluminescence devices based on quantum dots achieved tremendous progress. These encouraging facts foreshadow the commercialization of quantum-dot light-emitting diodes (QLEDs), which promises an unprecedented generation of cost-effective, large-area, energy-saving, wide-color-gamut, ultra-thin and flexible displays. Here we provide a Progress Report, covering interdisciplinary aspects including material chemistry of quantum dots and charge-transporting layers, optimization and mechanism studies of prototype devices and processing techniques to produce large-area and high-resolution red-green-blue pixel arrays. We also identify a few key challenges facing the development of active-matrix QLED displays.

The influence of the hole transport layers on the performance of blue and color tunable quantum dot light‐emitting diodes

“…Figure shows the schematic device structure and the energy band diagram of blue QLEDs. Various organic materials such as poly[N,N′‐bis(4‐butylphenyl)‐N,N′‐bis(phenyl)‐benzidine] (poly‐TPD); 4,4′‐bis(carbazole‐9‐yl)biphenyl (CBP); 4,4′,4″‐tri(9‐carbazoyl)‐triphenylamine (TcTa); and N,N′‐dicarbazolyl‐3,5‐benzene (mCP) have been used as HTLs for QLEDs . For appropriate HTLs, the materials should have deep‐lying HOMO levels and high hole mobility so that hole injection is efficient.…”

“…In addition, the HTLs also function as electron blocking layer, and therefore, they should have low LUMO levels to block the excess electrons overflowing from the QDs. Among the reported HTLs, PVK and TFB are the two most widely used HTLs in blue QLEDs due to their strengths of solution‐processable property, deep HOMO level, and high hole mobility …”

Perovskite Quantum Dots and Their Application in Light‐Emitting Diodes

“…High color purity and color‐tunable wavelength of QDs make them promising candidates for next‐generation displays. QD‐based LEDs can be separated into light converter (white‐light LEDs) and active‐mode QD‐LEDs (QLEDs) . We introduce these two types in the following sections.…”

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

“…Therefore, recently colloidal QDs are used as an emission component of WLEDs owing to their desirable properties, including high quantum yield, size-tunable emission spectrum, narrow emission bandwidth, and photo/ thermal stability. [13][14][15] Considerable efforts have been devoted toward realizing highly efficient QD-based WLEDs.…”