Multicolor Light-Emitting Diodes Based on Semiconductor Nanocrystals Encapsulated in GaN Charge Injection Layers

Abstract

Numerous technologies including solid-state lighting, displays, and traffic signals can benefit from efficient, color-selectable light sources that are driven electrically. Semiconductor nanocrystals are attractive types of chromophores that combine size-controlled emission colors and high emission efficiencies with excellent photostability and chemical flexibility. Applications of nanocrystals in light-emitting technologies, however, have been significantly hindered by difficulties in achieving direct electrical injection of carriers. Here we report the first successful demonstration of electroluminescence from an all-inorganic, nanocrystal-based architecture in which semiconductor nanocrystals are incorporated into a p-n junction formed from GaN injection layers. The critical step in the fabrication of these nanocrystal/GaN hybrid structures is the use of a novel deposition technique, energetic neutral atom beam lithography/epitaxy, that allows for the encapsulation of nanocrystals within a GaN matrix without adversely affecting either the nanocrystal integrity or its luminescence properties. We demonstrate electroluminescence (injection efficiencies of at least 1%) in both single- and two-color regimes using structures comprising either a single monolayer or a bilayer of nanocrystals.

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

“…In the initial study, QD layers were sandwiched between p-type and n-type GaN (EQE <0.01%). 85 In the following works, QLEDs with all-inorganic CTLs composed of metal oxides (e.g., ZnO, SnO 2 , ZnS, NiO, and WO 3 ) were demonstrated. [86][87][88] These devices exhibited superior stability under long-term usage and high-current-density conditions, which would be potentially beneficial for future flexible display applications.…”

Ag colloids and arrays for plasmonic non-radiative energy transfer from quantum dots to a quantum well

“…Hybrid semiconductor structures of quantum dots (QDs) and quantum wells (QWs) can play a large role in optoelectronic devices for photovoltaics [1][2][3], white light generation [4][5][6], and color conversion [7][8][9][10]. QDs provide the capability to collect sunlight over the full visible spectrum, and into the infrared [11][12][13], and InGaN/GaN QWs are also studied as a promising avenue for solar cell technology [14,15].…”

Surface Modification of CdSe and CdS Quantum Dots-Experimental and Density Function Theory Investigation

“…The sizedependent optical properties of QDs have been actively studied during the pass decade. The synthesis and subsequent functionality of QDs for a variety of applications include photostable luminescent biological labels [3][4][5][6][7][8], light harvesters in photovoltaic devices [9][10][11][12][13][14][15] and as the emissive material in light-emitting devices (LEDs) [16][17][18][19][20][21][22][23]. They are also characterized by large surface to volume ratios.…”