Excitonic improvement of colloidal nanocrystals in salt powder matrix for quality lighting and color enrichment

Abstract

Here we report excitonic improvement in color-converting colloidal nanocrystal powders enabled by co-integrating nonpolar green- and red-emitting nanocrystal energy transfer pairs into a single LiCl salt matrix. This leads to nonradiative energy transfer (NRET) between the co-integrated nanocrystals in the host matrix. Here we systematically studied the resulting NRET process by varying donor and acceptor concentrations in the powders. We observed that NRET is a strong function of both of the nanocrystal concentrations and that NRET efficiency increases with increasing acceptor concentration. Nevertheless, with increasing donor concentration in the powders, NRET efficiency was found to first increase (up to a maximum level of 53.9%) but then to decrease. As a device demonstrator, we employed these NRET-improved nanocrystal powders as color-converters on blue light-emitting diodes (LEDs), with the resulting hybrid LED exhibiting a luminous efficiency >70 lm/W(elect). The proposed excitonic nanocrystal powders potentially hold great promise for quality lighting and color enrichment applications.

Colloidal Nanocrystals Embedded in Macrocrystals: Methods and Applications

“…On the basis of this hypothesis, Erdem et al hybridized nonpolar green-and red-emitting NCs within LiCl salt. 13 The analyses of the emission dynamics revealed a nonradiative energy transfer efficiency reaching ∼54%, which is almost twice the value obtained in anthracene macrocrystals. 22 The authors also prepared a proof-of-concept of an excitonically improved light-emitting diode employing these powders.…”

“…19 These were subsequently integrated with UV LEDs, forming purecolor emitting LEDs. A proof-of-concept blue-green LED was prepared by Erdem et al 13 In this work, green-emitting core/ alloyed shell NCs were immobilized within LiCl. These NCs were shown to protect the initial QY after forming their powders, and their LEDs were prepared by encapsulating them with a commercially available epoxy resin on a blue LED.…”

“…This is an important strength of this material system for the LED and display producers. In addition, these NC-macrocrystals have been shown to provide a robust platform for studying environment-sensitive interparticle interactions such as plasmonics and excitonics. , As an interesting application, the NCs in macrocrystals have been very recently proposed as sensitive thermometers using strong variations observed in their emission spectra as a function of temperature …”

A Review on Halide Perovskites as Color Conversion Layers in White Light Emitting Diode Applications

“…They reported that the resulting white light possessed CRI of 89.2 with color coordinates of (0.3413, 0.3329) under 350 mA operation. Apart from polymers, perovskites can be prepared by incorporating them into microcrystals similar to QDs embedded in inorganic salts, which can lead to enhancement of the photo and chemical stabilities …”

Colloidal nanophotonics: the emerging technology platform

“…S. Gonzalez-Carrero et al [2] highlight advances on fabrication and characterization of a new class of semiconductor quantum dots, namely perovskite nanocrystals of lead halides. T. Erdem with associates [3] discuss possible ways to improve by means of salt powder matrix quantum dot based luminophores for lighting. Several research groups contributed with the works on improvement of quantum dot based devices.…”