Open AccessConcerning the stability of biexcitons in hybrid HJ aggregates of π-conjugated polymers
Author(s) -
Eric R. Bittner,
Carlos SilvaAcuña
Publication year - 2022
Publication title -
journal of chemical physics online/the journal of chemical physics/journal of chemical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.071
H-Index - 357
eISSN - 1089-7690
pISSN - 0021-9606
DOI - 10.1063/5.0090515
Subject(s) - biexciton , exciton , conjugated system , dipole , chemical physics , polymer , materials science , bound state , coherence (philosophical gambling strategy) , physics , molecular physics , condensed matter physics , quantum mechanics , composite material
Frenkel excitons are the primary photoexcitations in organic semiconductors and are ultimately responsible for the optical properties of such materials. They are also predicted to form \emph{bound} exciton pairs, termed biexcitons,which are consequential intermediates in a wide range of photophysical processes.Generally, we think of bound states as arising from an attractive interaction. However,here we report on our recent theoretical analysispredicting the formation of stable biexciton statesin a conjugated polymer material arising from both attractive and repulsive interactions.We show that in J-aggregate systems, 2J-biexcitonscan arise from repulsive dipolar interactions with energies $E_{2J}> 2E_J$ while in H-aggregates, 2H-biexciton states $E_{2H} < 2E_H$ corresponding to attractive dipole exciton/exciton interactions. These predictions are corroborated by using ultrafast double-quantum coherence spectroscopy on a PBTTT material that exhibits both J- and H-like excitonic behavior.