基于热激子机制的D-π-A结构有机激光材料构筑及其激发态辐射特性研究

The reduction of threshold current density is crucial for moving closer toward the realization of current-injection organic semiconductor laser. Therefore, the optical gain media as the core of laser should possess the characteristics of low threshold of amplified spontaneous emission (ASE) under optical excitation, high exciton utilizing efficiency and low efficiency roll-off under electrical pumping simultaneously. At present, for the known laser materials, the absence of triplet excitons for the lasing process leads to noteworthy energy dissipation. However, hot exciton fluorescence materials with reverse intersystem crossing of high-lying triplet state guarantee superior radiative decay rate kr, and suppress the efficiency roll-off by reducing the accumulation of triplet state T1 as well, which are expected to achieve the characteristics above at the same time. A new strategy that is to design novel hot exciton laser materials with D-π-A structure is developed in this project. The adjustment of excited-state photophysical properties through the introduction of strong conjugated group with large T1-T2 energy gap and the tailoring of D and A moieties can achieve optical transition with high kr from local excited sate, efficient hot exciton reverse intersystem crossing channel from charge transfer state and suppression of efficiency roll-off from the reduction of internal conversion. In this project, the new series of materials will be synthesized. The combination of quantum chemical calculations and experiments will be utilized to investigate the relationship among molecular structure, photophysical properties, ASE performance and electroluminescence radiation mechanism. The aim is to provide a new material system and principle of molecular design to develop novel laser materials for applying to current-injection organic semiconductor laser, so the project has very important theoretical and practical application value.

电泵浦有机半导体激光器的实现需降低阈值电流密度，因此作为其核心的光增益介质需兼具光泵浦下低自发辐射放大（ASE）阈值、电注入下高激子利用率和低效率滚降的特点，目前报道的有机激光材料因无法利用三线态激子导致能量浪费。而利用高能量三线态反系间窜越的热激子材料既可保证较高辐射衰减速率kr，又可降低三线态T1积累从而抑制效率滚降，有望同时实现上述特点。本项目提出构筑D-π-A结构热激子激光材料新策略，通过引入较大T1-T2能级差的强共轭基团和裁剪D、A单元调控激发态光物理特性，可实现基于局域态特性的高kr辐射、高效的电荷转移特性热激子反系间窜越通道及T1态积累的抑制（内转换受阻）。本项目拟设计合成系列材料，利用量化计算和实验相结合的方法，研究分子结构与光物理性质、ASE特性、电致器件辐射机制之间的关系，旨在为发展面向电泵浦应用的有机激光材料提供新的分子体系和设计原则，因而具有重要的理论和应用价值。

电泵浦有机半导体激光器的实现需降低阈值电流密度，因此作为其核心的光增益介质需兼具光泵浦下低自发辐射放大（ASE）阈值、电注入下高激子利用率和低效率滚降的特点，目前报道的有机激光材料因无法利用三线态激子导致能量浪费。而利用高能量三线态反系间窜越的热激子材料既可保证较高辐射衰减速率kr，又可降低三线态T1积累从而抑制效率滚降，有望同时实现上述特点。本项目提出构筑D-π-A结构热激子激光材料新策略，通过引入较大T1-T2能级差的强共轭基团和裁剪D、A单元调控激发态光物理特性，可实现基于局域态特性的高kr辐射、高效的电荷转移特性热激子反系间窜越通道及T1态积累的抑制（内转换受阻）。本项目拟设计合成系列材料，利用量化计算和实验相结合的方法，研究分子结构与光物理性质、ASE特性、电致器件辐射机制之间的关系，旨在为发展面向电泵浦应用的有机激光材料提供新的分子体系和设计原则，因而具有重要的理论和应用价值。