Dr. Junkai Liu


Room-temperature phosphorescence (RTP) materials have attracted wide attentions due to their application potential in sensing, data-encryption, bioimaging and optoelectronic devices.1 However, improving RTP efficiency and lifetime simultaneously in metal-free systems remains the biggest challenge for realizing their applications. Herein, by exploiting long-lifetime triplets of naphthalene (NL) and intersystem crossing (ISC)-promoting factors from 1,4-dichlorobenzene (DCB), we unveil a novel guest/host system (NL/DCB) with concurrently high RTP quantum yield of >20% and ultralong lifetime of >760 ms (afterglow duration > 10 s) at ambient conditions, which is the best RTP performance for a phosphor with pure π-π* transition. Based on systematic investigation of the photophysical properties of NL in a variety of host molecules, the underlying mechanism for efficient RTP of NL is elucidated to be the formation of unique cluster excitons that boost ISC and triplet population of NL molecules.2  



  1. Su, Y.; Phua, S. Z. F.; Li, Y.; Zhou, X.; Jana, D.; Liu, G.; Lim, W. Q.; Ong, W. K.; Yang, C.; and Zhao, Y. Sci. Adv. 2018, 4, eaas9732.
  2. Zhang, X.#; Liu, J.#; Chen, B.#; He, X.; Li, X.; Wei, P.; Gao, P.; Zhang, G.; Lam, J. W. Y.; Tang, B. Z. Matter, 2022, DOI: 10.1016/j.matt.2022.07.010.  

University: HKTUST

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