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rISC - the game of strategic molecular design for high efficiency OLEDs

rISC - 高效率 OLED 战略分子设计游戏

基本信息

批准号：
EP/T022477/1
负责人：
Peter Skabara
金额：
$ 57.76万
依托单位：
University of Glasgow
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2021
资助国家：
英国
起止时间：
2021 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=EP%2FT022477%2F1
关键词：
rISC game strategic molecular design

项目摘要

Lighting and displays form essential parts of our daily lives and consume approximately 20% of the electricity used worldwide. It has been shown that lights visible from space at night time are an effective measure of a country's economic development, while energy capture through the development of materials that absorb more sunlight is at the heart of attempts to reduce our reliance upon unsustainable fuel sources. In the context of generating light, Organic Light Emitting Diodes (OLEDs) are a rapidly expanding technology which are highly appealing owing to their potential high energy efficiency and ability to be printed roll-to-roll on a plastic substrate. However, in terms of efficiency, initial attempts to implement OLEDs based upon purely organic materials were restricted by the type of excited state which emits the light. Indeed, upon electrical excitation 25% of the emitting molecules are in emissive singlet excited state, whilst 75% are in non-emissive triplet excited states. However, conventional organic materials cannot emit from the triplet excited states. The proposal consists of developing a new class of OLEDs that exploits thermally activated delayed fluorescence (TADF). Here a triplet state is thermally activated to become iso-energetic with a singlet excited state, enabling efficient rISC into a radiative singlet manifold. One of the major challenges that must be overcome in TADF materials is that the use of pure-organic materials means that the often weak spin-orbit coupling between the singlet and triplet states can lead to rISC rates that extend into the millisecond range. This causes poor roll-off in device efficiency at higher current densities. However, through a new conceptual design of TADF molecules, we have shown that it is possible to achieve both a reverse intersystem crossing (rISC) rate > 1E7 s-1 and a unity photoluminescence quantum yield (PLQY), a combination previously considered untenable.In this proposal we will combine detailed synthetic, computational and photophysical studies to develop approaches for exploiting steric hindrance and non-covalent interactions to exert finer conformational control of the excited state dynamics to enhance functional properties. This is performed in conjunction with detailed studies to establish a deeper understanding of the excited states and their geometries formed by charge recombination. This proposal will deliver new understanding about the emission processes in TADF OLEDs and how to enhance the rISC rate to beyond 1E8 s-1 whilst retaining PLQY ~ 1. Achieving these outcomes will have a major disruptive impact on the OLED industry and ensure that the UK remains in the lucrative OLED materials supply chain.

照明和显示器是我们日常生活的重要组成部分，消耗了全球约20%的用电量。研究表明，夜间从太空中看到的灯光是衡量一个国家经济发展的有效指标，而通过开发吸收更多阳光的材料来捕获能量是减少我们对不可持续燃料来源依赖的核心。在产生光的背景下，有机发光二极管（oled）是一项迅速发展的技术，由于其潜在的高能效和在塑料基板上卷对卷印刷的能力，它非常吸引人。然而，在效率方面，基于纯有机材料实现oled的最初尝试受到发射光的激发态类型的限制。事实上，在电激发下，25%的发射分子处于发射单线态激发态，而75%的发射分子处于非发射三重态激发态。然而，传统的有机材料不能从三态激发态发射。该提案包括开发一类利用热激活延迟荧光（TADF）的新型oled。在这里，三重态被热激活，成为具有单线态激发态的等能态，使高效的rISC成为辐射单线态流形。在TADF材料中必须克服的主要挑战之一是，纯有机材料的使用意味着单线态和三重态之间通常较弱的自旋轨道耦合可能导致rISC速率扩展到毫秒范围。在较高的电流密度下，这会导致器件效率的低滚降。然而，通过TADF分子的新概念设计，我们已经证明有可能实现反向系统间交叉（rISC）速率bb0 1E7 s-1和统一光致发光量子产率（PLQY），这两个组合以前被认为是站不住脚的。在本提案中，我们将结合详细的合成，计算和光物理研究来开发利用位阻和非共价相互作用的方法，以施加激发态动力学的精细构象控制，以增强功能特性。这是与详细的研究一起进行的，以建立对激发态及其由电荷重组形成的几何形状的更深层次的理解。该提案将提供对TADF oled发射过程的新理解，以及如何在保持PLQY ~ 1的同时将rISC速率提高到1E8 s-1以上。实现这些成果将对OLED产业产生重大的颠覆性影响，并确保英国仍处于利润丰厚的OLED材料供应链中。