Open AccessSignificant role of spin-triplet state for exciton dissociation in organic solids
Author(s) -
Takahiko Yamanaka,
Hajime Nakanotani,
Chihaya Adachi
Publication year - 2022
Publication title -
science advances
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.928
H-Index - 146
ISSN - 2375-2548
DOI - 10.1126/sciadv.abj9188
Subject(s) - excited state , singlet fission , exciton , dissociation (chemistry) , triplet state , singlet state , spin states , chemical physics , spin (aerodynamics) , atomic physics , chemistry , physics , condensed matter physics , thermodynamics
Clarification of the role of the spin state that initiates exciton dissociation is critical to attaining a fundamental understanding of the mechanism of organic photovoltaics. Although an excited spin-triplet state with an energy lower than that of excited spin-singlet state is disadvantageous in exciton dissociation, a small electron exchange integral results in small singlet-triplet energy splitting in some material systems. This energy splitting leads to a nearly isoenergetic alignment of both excited states, raising a question about the role of excited spin states in exciton dissociation. Herein, we show that the spin-triplet rather than the spin-singlet plays a critical role in the exciton dissociation that leads to the formation of free carriers. This result indicates that the spin-triplet inherently acts as an intermediate, leading to exciton dissociation. Thus, our demonstration provides a fundamental understanding of the role of excited spin states of organic molecular systems in photoinduced charge-carrier generation.