磷光发射是分子激发态的特征之一.由于有机分子的三重态具有较长的寿命,允许激子长距离迁移,因此在光伏器件、光催化反应、显示与照明体系、分子传感和生物成像等光电领域具有广泛的应用前景.但由于有机化合物的磷光通常需要苛刻的条件(低温、无氧),这一领域的发展一直比较缓慢.近年来,科学家开始探索各种促进有机分子室温磷光的手段.从分子设计上,引入芳香羰基、重原子效应、氘代等促进三重态的产生;从材料设计上,利用主体分子和客体分子之间的作用,刚性的固相结晶结构,聚合物等来稳定有机分子的三重态,减少非辐射失活途径.很多研究中都是利用多种手段相结合的方法,最终获得长寿命、高量子产率的磷光材料.本文从长寿命磷光材料的构筑手段上进行分类,综述了近5年来室温磷光材料的最新研究进展及应用,并对今后的发展方向进行了展望.
Phosphorescence is among the many functional features of long-lived triplet excited states enable exciton migration the excited organic molecules. Organic molecules with over long distance, which is essential in a variety of optoelectronic applications such as photovoltaics, photocatalytic reactions, display and lighting system, molecular sensing and biological imaging. In general, phosphorescence materials involve the organometallic compounds that are expensive, such as Pt, Ir and so on. Owing to the presence of metal, the phosphorescence materials is toxic and are also intrinsically unstable in the case of high-energy blue emitters. Therefore the purely organic materials that show room-temperature phosphorescence (RTP) are attractive alternatives to organometallic phosphors. The triplet excitons are not commonly generated in organic materials and are mostly consumed through radiationless processes, such as vibrational dissipation and oxygen-mediated quenching, under ambient conditions. Recently, a variety of methods from molecular design to material design to access organic room temperature phosphorescence have been explored. This review focus on the recent advancements in the field of organic phosphorescence, classifying the strategies based on material design. The outlook of organic room temperature phosphorescence is also discussed. The basic concepts for RTP process are introduced to demonstrate what's the key factors to obtain efficient RTP. They are: (1) the promotion of both singlet-to-tdplet and triplet-to-singlet intersystem crossing, and (2) suppression of the nonradiative quenching processes from the triplet to the ground state. Comparisons between RTP and delayed fluorescence are also made in the review. The triplet excited states of organic molecules can be stabilized by interactions of host molecules and guest molecules, rigid solid-crystallized structures and the chromophore embedded in polymer, which can suppress the nonradiative deactivation pathways and rates of triplet excito