Pure-organic phosphine oxide luminescent materials

Phosphine-oxide-(PO)-based optoelectronic materials are attracting increasing attention owing to the unique advantages of P = O groups in modulating the molecular configuration, excited-state properties, and intermolecular interactions. P = O groups are also effective for the molecular design of high-performance luminescent materials. In this review, the research progress of pure-organic PO materials for light-emitting applications with high radiation is summarized. After a brief introduction about the luminescent mechanisms and the functions of P = O groups, this review focuses on the material design and structural-property relationships, especially the influences of P = O groups on the material performances, which are divided into three chapters according to the mechanisms of fluorescent (FL), thermally active delayed fluorescent (TADF), and charge-transfer-(CT)-based long-afterglow materials. It was shown that the electron-withdrawing effect and the insulating character of the P = O joint could improve the electrical properties and enhance inter - and intramolecular CT without remarkably changing the emission color, making it almost 'ideal' for blue emitters. The steric hindrance of 3D PO molecules further suppressed the quenching effects for emission efficiency improvement. These superiorities guarantee that the pure-organic PO system is one of the best fluorescent materials for diverse applications.