Purely organic room-temperature phosphorescence (RTP) materials have been a hot research topic. Currently, the pure RTP materials have been realized by the introduction of heavy halogen atoms, carbonyls groups or some heteroatoms, hydrogen bonding, H-aggregation, strong intermolecular electronic coupling, molecular packing, host-guest interaction, etc. However, the complicated synthesis and high expenditure are still inevitable in these systems. In addition, their performances in air are not satisfactory and the introduction of halogen atoms is generally necessary. Therefore, a new facile and robust host-guest strategy utilizing only electron-rich materials is a promising alternative for constructing RTP systems.
Very recently, Zheng and Qin et al. developed a series of novel host-guest organic phosphorescence systems, in which N,N,N’,N’-tetraphenylbenzidine (TPB) acted as a guest, triphenylphosphine (TPP) or triphenylamine (TPA) served as a host. The maximum phosphorescence efficiency and the longest lifetime could reach 23.6% and 362 ms, respectively. Experimental results and theoretical calculation revealed that the host molecules not only play a vital role in providing a rigid environment and suppressing non-radiative decay of the guest, but also show a synergistic effect to the guest in the photo-physical process through Förster resonance energy transfer (FRET). These new host-guest RTP systems enjoy the integrated merits of commercially available compounds with electron-rich features and low cost, absence of halogen atoms, facile preparation and excellent performances, etc., which shows great potentials in practical applications. Therefore, this work broadens the way for the fabrication of purely organic RTP materials and offers a novel platform for the development of diverse applications.
Featured image : The chemical structures of TPB, TPP and TPA, the phosphorescence of TPB/TPP and TPB/TPA crystalline powders, the advantages of these new host-guest RTP systems. ©Science China Press
Reference: Ning, Y., Yang, J., Si, H. et al. Ultralong organic room-temperature phosphorescence of electron-donating and commercially available host and guest molecules through efficient Förster resonance energy transfer. Sci. China Chem. (2021). https://link.springer.com/article/10.1007/s11426-020-9980-4 https://doi.org/10.1007/s11426-020-9980-4
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