TY - JOUR

T1 - Way to Highly Emissive Materials

T2 - Increase of Rigidity by Introduction of a Furan Moiety in Co-Oligomers

AU - Koskin, Igor P.

AU - Mostovich, Evgeny A.

AU - Benassi, Enrico

AU - Kazantsev, Maxim S.

PY - 2017/10/26

Y1 - 2017/10/26

N2 - Rigid linear organic co-oligomers are prospective materials for organic optoelectronics. In this work, we explored intramolecular factors affecting the torsional rigidity and its influence on optoelectronic properties of the alternating furan/phenylene and thiophene/phenylene co-oligomers in both ground and first singlet excited states. A furan/phenylene co-oligomer exhibits almost twice as high torsional rigidity than its thiophene analogue. The effect of intramolecular O···H and S···H interactions on torsional barriers was found to be negligible as compared with the conjugation efficiency. The higher torsional rigidity of furan and thiophene co-oligomers has been proven to be reflected in the fine structure of the UV-vis absorption spectrum of the former. The increase of furan co-oligomer rigidity as compared with its thiophene analogue lowers reorganization energy for hole, electron, and exciton transfer. Remarkably the substitution of thiophene by furan lowers by almost 20 times the reorganization energy for exciton transfer. A noteworthy finding was also that in furan co-oligomer the higher rigidity was suggested to hinder "in molecule" photoluminescence quenching due to a possible conical intersection between bright state S1 and the T3 excited state. Therefore, tuning of torsional rigidity impacts emission and charge transport properties, being a very powerful tool on the way to high performance emissive organic semiconductors.

AB - Rigid linear organic co-oligomers are prospective materials for organic optoelectronics. In this work, we explored intramolecular factors affecting the torsional rigidity and its influence on optoelectronic properties of the alternating furan/phenylene and thiophene/phenylene co-oligomers in both ground and first singlet excited states. A furan/phenylene co-oligomer exhibits almost twice as high torsional rigidity than its thiophene analogue. The effect of intramolecular O···H and S···H interactions on torsional barriers was found to be negligible as compared with the conjugation efficiency. The higher torsional rigidity of furan and thiophene co-oligomers has been proven to be reflected in the fine structure of the UV-vis absorption spectrum of the former. The increase of furan co-oligomer rigidity as compared with its thiophene analogue lowers reorganization energy for hole, electron, and exciton transfer. Remarkably the substitution of thiophene by furan lowers by almost 20 times the reorganization energy for exciton transfer. A noteworthy finding was also that in furan co-oligomer the higher rigidity was suggested to hinder "in molecule" photoluminescence quenching due to a possible conical intersection between bright state S1 and the T3 excited state. Therefore, tuning of torsional rigidity impacts emission and charge transport properties, being a very powerful tool on the way to high performance emissive organic semiconductors.

UR - http://www.scopus.com/inward/record.url?scp=85032628246&partnerID=8YFLogxK

U2 - 10.1021/acs.jpcc.7b08305

DO - 10.1021/acs.jpcc.7b08305

M3 - Article

AN - SCOPUS:85032628246

VL - 121

SP - 23359

EP - 23369

JO - Journal of Physical Chemistry C

JF - Journal of Physical Chemistry C

SN - 1932-7447

IS - 42

ER -