Access to Triplet Excited State in Core-Twisted Perylenediimide

Nagarajan, Kalaivanan ; Mallia, Ajith R. ; Reddy, V. Sivaranjana ; Hariharan, Mahesh (2016) Access to Triplet Excited State in Core-Twisted Perylenediimide Journal of Physical Chemistry C, 120 (16). pp. 8443-8450. ISSN 1932-7447

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Official URL: http://doi.org/10.1021/acs.jpcc.6b00755

Related URL: http://dx.doi.org/10.1021/acs.jpcc.6b00755

Abstract

Solvent-free crystal structure of N,N-bis(propylacetyl)-1,6,7,12-tetrabromoperylene-3,4:9,10-bis(dicarboximide), PDI-Br4, obtained by X-ray diffraction reveals the core-twisted perylene motif having π–π stacks at an interplanar separation of 3.7 Å. Slip-stacked arrangement of PDI units in PDI-Br4 arises due to the presence of bulky bromine atoms. Femtosecond pump–probe measurements of monomeric PDI-Br4 in toluene reveal ultrafast intersystem crossing (τISC < 110 fs) when excited at 400 nm. Triplet quantum yield (ΦT) of 19 ± 1% and 105 ± 5% for PDI-Br4 in toluene and vapor-annealed polycrystalline 60 nm thick film respectively are estimated from nanosecond transient absorption measurements. Quantum chemical calculations show that the combined effects of heavy atom and core-twist in PDI-Br4 can activate the intersystem crossing by altering the singlet–triplet energy gap. Enhanced quantum yield accounts for the singlet fission mediated generation of triplet excited state in the PDI-Br4 thin film.

Item Type:Article
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ID Code:126884
Deposited On:17 Oct 2022 05:31
Last Modified:17 Oct 2022 05:31

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