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Dinuclear Metal Complexes for Near-Infrared Organic Light Emitting Diodes

用于近红外有机发光二极管的双核金属配合物

基本信息

批准号：
EP/S012788/1
负责人：
JAG Williams
金额：
$ 96.34万
依托单位：
Durham University
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2019
资助国家：
英国
起止时间：
2019 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=EP%2FS012788%2F1
关键词：
Dinuclear Metal Complexes Near Infrared

项目摘要

This project aims to create new devices that brightly emit deep red and / or near infrared (NIR) light with high efficiency.The near-infrared (NIR) refers to that region of the electromagnetic spectrum that is just beyond what the eye perceives as red light. A typical definition is the wavelength range 700-1400 nm. NIR radiation has lower energy than visible light. Though invisible to the eye, the NIR is a technologically important region of the spectrum, readily detectable using widely available instrumentation; e.g. low-cost silicon detectors work to around 1000 nm and peak at about 850 nm. The NIR is commonly used in telecommunications, features in night vision systems, and can be applied to security devices such as fingerprint technology. It is also particularly well-suited to applications where light is used in the diagnosis or treatment of disease - since biological tissue is most transparent to this region of light.There have been huge advances in visible light-emitting technology over the past 20 years. Amongst them, organic light emitting diodes (OLEDs) are proving particularly attractive, as they are energy-efficient, flexible and light-weight, amenable to mass production, and well-suited to large-area displays. Metal complexes have a key role to play here. Their spin-orbit coupling (SOC) offers a means of harnessing triplet states that are otherwise non-emissive due to the spin-selection rule. Triplet states are formed in ratios as high as 3:1 relative to singlet states upon charge combination in a device, so the ability to induce triplet emission offers large gains in efficiency. In a mobile phone, for example, this directly translates into less power consumption ... and longer time intervals between charging of the battery.Yet, there are very few OLEDs for the NIR region, and most investigated to date have low efficiency. A number of factors conspire to reduce the luminescence quantum yield of molecular materials that emit at low energy - in the deep red and NIR regions. Non-radiative decay through coupling of the electronic excited state with higher vibrational levels of the ground state becomes more efficient as excited-state energy decreases, owing to greater Franck-Condon overlap of pertinent vibrational levels - the so-called "energy gap law". For organometallic emitters, this is compounded by typically lower phosphorescence rate constants in the red / NIR, since the amount of metal character in the excited state tends to decrease with increasing ligand conjugation.The challenges we seek to address are thus, simultaneously:(1) to design and synthesise red / NIR-emitting phosphorescent molecules in which vibrational non-radiative decay channels are minimized;(2) to develop strategies by which SOC pathways can be made more efficient for such molecules, so that phosphorescence can be facilitated and compete effectively with non-radiative decay. We will synthesise target molecules containing two or more metal ions, designed to meet the above challenges. Having studied their emission properties in the desired region of the spectrum, we will then use them to prepare deep red and NIR-emitting OLEDs, experimenting with different device architectures for maximization of efficiency, and devising methods for the systematic evaluation of devices operating in this region.Our goals by the end of the project will be to have:(1) prepared a diverse range of new multinuclear complexes showing low-energy emission;(2) developed a clear understanding of SOC pathways in multinuclear complexes;(3) obtained phosphorescent OLEDs operating in the NIR region that have efficiencies substantially higher than any others reported to date (our target is to exceed 40% efficiency).

该项目旨在创造出高效率地发出明亮的深红色和/或近红外（NIR）光的新设备。近红外（NIR）是指电磁波谱中刚好超出眼睛感知为红光的区域。典型的定义是波长范围700-1400 nm。NIR辐射的能量比可见光低。虽然肉眼不可见，但近红外是光谱中技术上重要的区域，使用广泛可用的仪器很容易检测到;例如，低成本的硅探测器工作在1000 nm左右，峰值在850 nm左右。NIR通常用于电信，夜视系统中的功能，并可应用于指纹技术等安全设备。它也特别适用于光用于疾病诊断或治疗的应用-因为生物组织对这一区域的光最透明。在过去的20年里，可见光发射技术取得了巨大的进步。其中，有机发光二极管（OLED）被证明特别有吸引力，因为它们节能，灵活和重量轻，适合大规模生产，并且非常适合大面积显示器。金属配合物在这里发挥着关键作用。它们的自旋轨道耦合（SOC）提供了一种利用三重态的方法，这些三重态由于自旋选择规则而不发射。在器件中电荷组合时，三重态相对于单重态以高达3：1的比率形成，因此诱导三重态发射的能力提供了效率的大增益。例如，在移动的电话中，这直接转化为更少的功耗.然而，用于NIR区域的OLED非常少，并且迄今为止研究的大多数OLED具有低效率。许多因素共同降低了分子材料的发光量子产率，这些分子材料在深红色和近红外区域发射低能量。通过电子激发态与基态的更高振动能级的耦合的非辐射衰变随着激发态能量的降低而变得更有效，这是由于相关振动能级的更大的弗兰克-康登重叠-所谓的“能隙定律”。对于有机金属发光体，由于激发态的金属特征量随着配体共轭的增加而减少，因此在红光/ NIR中的磷光速率常数通常较低，因此我们寻求解决的挑战是，同时：（1）设计和合成红光/NIR磷光分子，其中振动非辐射衰减通道最小化;（2）开发策略，通过该策略可以使SOC途径对于这些分子更有效，使得磷光可以被促进并与非辐射衰变有效竞争。我们将合成含有两种或更多种金属离子的目标分子，旨在满足上述挑战。在研究了它们在所需光谱范围内的发射特性之后，我们将用它们来制备深红色和近红外发射OLED，实验不同的器件结构以最大化效率，并设计系统评估在该区域工作的器件的方法。我们的目标是：（1）制备各种显示低能发射的新型多核配合物;（2）对多核络合物中的SOC途径有了清晰的理解;（3）获得了在NIR区域工作的磷光OLED，其效率大大高于迄今为止报道的任何其他OLED（我们的目标是超过40%的效率）。

项目成果

期刊论文数量（10）

专著数量（0）

科研奖励数量（0）

会议论文数量（0）

专利数量（0）

Exceptionally fast radiative decay of a dinuclear platinum complex through thermally activated delayed fluorescence.

DOI：
10.1039/d1sc00160d
发表时间：
2021-03-22
期刊：
Chemical science
影响因子：
8.4
作者：
Pander P;Daniels R;Zaytsev AV;Horn A;Sil A;Penfold TJ;Williams JAG;Kozhevnikov VN;Dias FB
通讯作者：
Dias FB

Simultaneous enhancement of thermally activated delayed fluorescence and photoluminescence quantum yield via homoconjugation

通过同共轭同时增强热激活延迟荧光和光致发光量子产率