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An Organic Laser Dye having a Small Singlet‐Triplet Energy Gap Makes the Selection of a Host Material Easier
Author(s) -
Karunathilaka Buddhika S. B.,
Balijapalli Umamahesh,
Senevirathne Chathuranganie A. M.,
Esaki Yu,
Goushi Kenichi,
Matsushima Toshinori,
Sandanayaka Atula S. D.,
Adachi Chihaya
Publication year - 2020
Publication title -
advanced functional materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.069
H-Index - 322
eISSN - 1616-3028
pISSN - 1616-301X
DOI - 10.1002/adfm.202001078
Subject(s) - lasing threshold , materials science , laser , singlet state , optoelectronics , dye laser , quenching (fluorescence) , photochemistry , optics , atomic physics , fluorescence , chemistry , excited state , wavelength , physics
Quenching of singlets by long‐lived triplets is a serious issue for lasing from organic laser dyes, especially under long pulse excitation. As a strategy to scavenge or manage unnecessary triplets, an organic laser dye is dispersed into a host material having high singlet and low triplet energy levels [a large singlet‐triplet energy gap (Δ E ST )]. However, finding such a host material having a triplet scavenging capability is limited. In this study, an organic laser dye, 2,6‐dicyano‐1,1‐diphenyl‐λ 5 σ 4 ‐phosphinine (DCNP), having a small Δ E ST of ≈0.44 eV is synthesized, and thus 4‐4′‐bis[( N ‐carbazole)styryl] biphenyl (BSBCz) can be employed as a triplet scavenging host, i.e., the triplets formed on DCNP are easily transferred to BSBCz. A 1 wt%‐DCNP‐doped BSBCz film is formed on a mixed‐order distributed feedback grating, showing lasing with a low threshold value of ≈0.86 µJ cm −2 and a full‐width‐at‐half‐maximum value of ≈0.5 nm. Because of the suppressed singlet‐triplet annihilation, DCNP‐based laser devices operating under a continuous‐wave regime, with a low threshold of 72 W cm −2 and a long laser half‐lifetime of ≈3 min, are demonstrated. These results indicate a possibility of the wider selection of host materials, easing a material design strategy of fabricating high‐performance laser devices in future.