Recently, a research team led by Professor Wenping Hu from Tianjin University has made a key contribution to exploring the thermally activated delayed fluorescence in an organic cocrystal, which was published online inAngewandte Chemieunder the title of “Thermally Activated Delayed Fluorescence (TADF) in an Organic Cocrystal: Narrowing the Singlet-Triplet Energy Gap via Charge Transfer”. 

The development of display technology has revolutionized people's daily life, whereinorganic light-emitting diodes (OLEDs) have attracted wide attention due to their advantages of being ultra-thin, light weight, flexible, and low cost, providing an opportunity for flexible wearable devices. The thermally activated delayed fluorescence materials, which are considered to be the third-generation OLED materials, can utilize the triplet excitons through the reversed intersystem crossing (RISC) process, breaking through the exciton statistics limit and improving the exciton utilization efficiency.

Cocrystal engineering has emerged as a promising research interest to construct functional materials, providing a platform for unveiling the structural-property relationships at a molecular level. The building blocks are assembled via heteromolecular interactions, which offer the opportunity to achieve noncovalent synthesis of functional molecules with the advantages of simple processing, easily tunable structure and low-cost.

Prof. Wenping Hu’s research group has observed thermally activated delayed fluorescence (TADF) in cocrystals for the first time, and the intermolecular charge transfer nature of cocrystal favors a small singlet-triplet energy gap to enhance the singlet-triplet spin mixing, which opens up a new way for the future design and development of novel TADF materials.

Link to the paper:https://doi.org/10.1002/anie.201904427

By Sun Lingjie from the School of Science

Editors: Eva Yin & Doris Harrington