Achieving Efficient Room-Temperature Phosphorescence in the Host–Guest System through Covalent-Bond-Strengthened Hydrogen Bonding

Achieving high performance room-temperature phosphorescence (RTP) with a clearly understood mechanism is highly desired. In this work, efficient RTP materials with a delayed emission quantum yield of 50% were synthesized through loading thiophenes into the matrix of inorganic boric acid (BA). The RTP mechanisms were clarified through structural, photophysical, and theoretical studies of RTP materials produced by loading a series of thiophenes into a BA matrix. Our study demonstrated the critical role of molecular interactions between BA and thiophenes. Covalent bonds have strengthened the hydrogen bonds to modulate the photophysical properties of thiophenes, which reduced the energy gap between the singlet and triplet states. The RTP color and emission lifetime could be well-tuned by substituting the chemical groups on the skeleton of thiophenes, which endowed their applications with information encryption. These results opened a door for designing efficient RTP materials for various applications as well as a clear mechanism for studying the host–guest systems.