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Self‐Assembled Helical Arrays for the Stabilization of the Triplet State
Author(s) -
Nidhankar Aakash D.,
Mohana Kumari Divya S.,
Chaubey Shailendra Kumar,
Nayak Rashmi,
Gonnade Rajesh G.,
Kumar G. V. Pavan,
Krishnan Retheesh,
Babu Sukumaran Santhosh
Publication year - 2020
Publication title -
angewandte chemie
Language(s) - English
Resource type - Journals
eISSN - 1521-3757
pISSN - 0044-8249
DOI - 10.1002/ange.202005105
Subject(s) - phosphorescence , intersystem crossing , triplet state , quantum yield , photochemistry , singlet state , fluorescence , materials science , molecule , chemistry , chemical physics , nanotechnology , atomic physics , excited state , physics , optics , organic chemistry
Room‐temperature phosphorescence of metal and heavy atom‐free organic molecules has emerged as an area of great potential in recent years. A rational design played a critical role in controlling the molecular ordering to impart efficient intersystem crossing and stabilize the triplet state to achieve room‐temperature ultralong phosphorescence. However, in most cases, the strategies to strengthen phosphorescence efficiency have resulted in a reduced lifetime, and the available nearly degenerate singlet‐triplet energy levels impart a natural competition between delayed fluorescence and phosphorescence, with the former one having the advantage. Herein, an organic helical assembly supports the exhibition of an ultralong phosphorescence lifetime. In contrary to other molecules, 3,6‐phenylmethanone functionalized 9‐hexylcarbazole exhibits a remarkable improvement in phosphorescence lifetime (>4.1 s) and quantum yield (11 %) owing to an efficient molecular packing in the crystal state. A right‐handed helical molecular array act as a trap and exhibits triplet exciton migration to support the exceptionally longer phosphorescence lifetime.