Research progress of full electroluminescent white light-emitting diodes based on a single emissive layer

Abstract

Carbon neutrality, energy savings, and lighting costs and quality have always led to urgent demand for lighting technology innovation. White light-emitting diodes (WLEDs) based on a single emissive layer (SEL) fabricated by the solution method have been continuously researched in recent years; they are advantageous because they have a low cost and are ultrathin and flexible. Here, we reviewed the history and development of SEL–WLEDs over recent years to provide inspiration and promote their progress in lighting applications. We first introduced the emitters and analysed the advantages of these emitters in creating SEL–WLEDs and then reviewed some cases that involve the above emitters, which were formed via vacuum thermal evaporation or solution processes. Some notable developments that deserve attention are highlighted in this review due to their potential use in SEL–WLEDs, such as perovskite materials. Finally, we looked at future development trends of SEL–WLEDs and proposed potential research directions.

Highly efficient green InP-based quantum dot light-emitting diodes regulated by inner alloyed shell component

“…Quantum dot light-emitting diodes (QLEDs) have received considerable attention during these years due to their extraordinary color purity, reliability, cost-effectiveness, and efficiency 1 – 6 . Considering that about 15% of the global electricity was used on lighting, these advantages made QLEDs become the most promising substitute of traditional light-emitting diodes and organic light-emitting diodes for efficient lighting and display 7 – 12 . Nowadays, the cadmium chalcogenide-based quantum dots (QDs) and QLEDs have made great achievement which has already devoted in application; 13 however, the intrinsic toxicity of Cd might inhibit their further development according to the restriction of hazardous substances directive 14 – 16 .…”

Solution-processed colloidal quantum dots for light emission

“…Another useful feature of QDs is that one can deposit them on most substrates at room temperature under ambient pressure, which means that one can create printable, flexible, and even rollable QD displays of all sizes. (74,(76)(77)(78) QLED displays have been created using two different methods: photoluminescence (PL, passive) and electroluminescence (EL, active). PL displays use a QD layer on top of a blue/near UV backlighting layer, which will cause the QDs to emit narrowband RGB colours.…”

“…This makes the performance of Cdbased QLEDs comparable to the latest OLEDs. (59,74,78,80). Due to the Cd toxic issue, the area of most recent materials interest is the creation of heavy metal-free environmentfriendly QLEDs.…”

Pb-free halide perovskites for solar cells, light-emitting diodes, and photocatalysts

“…Pb-based red LEDs emitting at 627 nm with an impressive EQE of 20.3% (starting from a PLQY of 88%) were obtained recently, although the operational stability remains limited to 1 h and the EQE drops very quickly for current densities above 1 mA cm −2 . The performances of blue Pb-based LEDs are more limited leading, for example, to an EQE of 12.3% starting from a PLQY over 90%, 167 or a sky-blue emitting device with an EQE of 13.8% but driven by a high voltage of above 4 V. 168 Finally, it shall be mentioned that demonstrations of single layer Pb-based white light LED do exist, 169 although with room for improvement. A promising EQE of 1.2% (starting from a PLQY of 85%) with a color rendering index (CRI) of 93 was, for example, obtained in 2020 using CsPbCl 3 quantum dots doped with Sm 3+ .…”