MID-INFRARED COLLOIDAL QUANTUM DOTS LEDs

本项目的目标是探索中红外胶体无机量子点发光二极管（QLED）。 对于可见光，QLED作为有机LED的竞争者而被广泛研究。溶液处理允许如此高的体积和面积生产，无论是无机量子点还是分子染料，都在彻底改变显示和照明技术。 该项目的不同之处在于旨在利用胶体量子点的特殊无机性质，原则上允许红外发光，并开始研究中红外QLED。应用将主要来自于中红外覆盖分子指纹区域的事实。 因此，无机量子点LED和探测器的组合，都是通过简单的溶液处理和印刷制成的，可以彻底改变分子传感。应用的例子可以是有毒或温室气体的传感以及食品工业中的脂肪或蛋白质含量。因此，该项目旨在开始中红外无机量子点LED的探索，包括合成新型明亮的中红外半导体量子点并将其纳入新型中红外发光二极管。 LED的发射效率与电子-空穴复合的光致发光效率成比例，沿着由于差的光子提取、俄歇效应和漏电流引起的其它损失。原则上，无机量子点应该是有效的中红外发色团，因为它们具有低的声子频率和低的电子态密度。然而，迄今为止，在5微米处发射的胶体量子点的记录效率仅为2%。据认为，这还不受多声子过程的限制，而是与表面或基质的表面和振动吸收有关。因此，该项目将采用材料合成方法来增加亮度。 与此同时，这些新的发色团将通过开发新的方法和借用为可见光QLED和更传统的中红外III-V族外延半导体中红外LEDs开发的策略，被纳入到中红外LED中。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

The objective of the project is to explore mid-infrared colloidal inorganic Quantum dot Light Emitting Diodes (QLEDs). For visible light, QLEDs are widely investigated as a competition to organic LEDs. The solution processing allows such high volume and area production that either approaches, inorganic quantum dots or molecular dyes, are revolutionizing the display and lighting technologies. This project differs in aiming to take advantage of the specifically inorganic nature of colloidal quantum dots which allows in principle infrared luminescence, and to start research on mid-infrared QLEDs. The applications will mostly derive from the fact that the mid-infrared covers the molecular fingerprint region. As such, a combination of inorganic quantum dot LEDs and detectors, both made by simple solution processing and printing, could revolutionize molecular sensing. Example of applications could be sensing of toxic or greenhouse gases as well as fat or protein content in the food industry. The project therefore aims to start the exploration of mid-infrared inorganic quantum dot LEDs, it includes the synthesis of novel bright mid-infrared semiconductor quantum dots and their incorporation into novel mid-infrared light emitting diodes. The emission efficiency of LED scales proportionally to the photoluminescence efficiency of electron-hole recombination, along with other losses due to poor photon extraction, Auger effects and leakage current. In principle, inorganic quantum dots should be efficient mid-IR chromophores, because they have low phonon frequencies and low electronic density of states. Yet, to date, the record efficiency for a colloidal quantum dot emitting at 5 microns is only 2%. It is thought that this is not yet limited by multiphonon processes but instead related to surface and vibrational absorption from surface or matrix The project will therefore pursue material synthetic approaches to increase the brightness. In parallel, these new chromophores will be incorporated into a mid-IR LED by developing new approaches and borrowing strategies developed for visible QLEDs and the more conventional mid-infrared III-V epitaxial semiconductor based mid-infrared LEDs.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.