有机体系电荷转移态超常磁场增强发光效应研究

External magnetic field can significantly affect the excited state behavior in photochemistry processes. Recent studies reveal that in some delayed fluorescence materials with charge-transfer characteristics, the luminescence intensity could be elevated by several or even tens of times with applied field. However, the mechanism behind this anomalous phenomenon is still not clear, and a reliable molecule-property relationship is needed to design and optimize materials. This proposal starts from the intramolecular and intermolecular charge-transfer features in donor-acceptor molecules, develops a new method to measure the magnetic field effect on fluorescence dynamics, and investigates the new mechanism in the conversion between spin states in charge-transfer materials based on the change of singlet and triplet levels under magnetic field, for example, the difference in the spin precession of positive and negative charges in excited states. Furthermore, we will look for possible magnetic field effects on photoluminescence, stimulated emission, and other photophysics and photochemistry processes, as well as design molecules and aggregates to efficiently convert triplet into singlet, which can largely improve the fluorescence efficiency of materials and devices, and benefit the application of charge-transfer compounds in magnetic field modulated light emitters, magnetic field assisted lasers, and other nonlinear organic photonics devices. This research would help us to better understand the spin photochemistry in charge-transfer excited states, and provide references to design and realize high-efficiency organic luminescent materials and functional devices.

外加磁场对光化学过程中的自旋激发态有着重要影响。近期研究发现，具有电荷转移特性的某些延迟荧光材料在磁场下发光强度可以增强数倍甚至数十倍，但其中机制和规律尚不清晰，需要建立可靠的分子-性能关系来设计优化材料体系。本项目从具有分子内、分子间电荷转移特性的有机体系出发，发展发光动力学的磁场效应测试新方法，从磁场下单重态、三重态的能级结构变化入手，研究基于电荷转移激发态的自旋态转化新机制，如激发态中正负电荷的自旋进动频率差异等，发掘光致发光、受激发射等光物理、光化学过程中可能存在的磁场效应，设计相应的分子、分子聚集体实现磁场下三重态到单重态的有效转化，从而大幅度提升材料和器件的荧光发光效率，探索电荷转移类化合物在磁场调控发光、磁场辅助激光等非线性有机光子学器件上的应用可能。本研究将有助于进一步理解电荷转移激发态中的自旋光化学过程，为设计实现高效有机发光材料及相关功能器件提供借鉴。

项目围绕外加磁场对电荷转移激发态的调控作用，系统研究了其中自旋依赖的光物理、光化学性质及其应用。.项目取得如下成果：（1）设计电荷转移类化合物体系制备了高效率OLED 器件，进行了磁电阻以及磁场影响发光的性质测试，提出了单重态-三重态自旋转化对器件性能的影响机制，利用自旋敏化剂促进反向系间窜越等自旋过程。（2）发展了磁场调控分子材料自组装的新方法，实现了外场对光子学耦合结构的原位实时调控，探索了其在磁调控激光器件方面的应用。（3）将电荷转移过程磁场效应拓展到光电化学反应体系，实现了磁场对反应速率、路径、产物的调控，探索了自旋增强催化反应的研究方向。.项目已发表研究论文13篇，申请专利2项，顺利完成研究目标。