title: Theoretical study on the charge transfer mechanism at donor/acceptor interface: Why TTF/TCNQ is inadaptable to photovoltaics?
abstract: A combined molecular dynamics (MD) and quantum chemical (QC) simulation method is utilized to investigate charge generation mechanism at TTF/TCNQ (tetrathiafulvalene/tetracyanoquinodimethane) heterojunction, which is a controversial donor/acceptor (D/A) interface for organic photovoltaic (OPV) devices. The TTF/TCNQ complexes extracted from MD simulation are classified into parallel and herringbone packings. And then, the amounts of charge transferred from ground states to different excited states and the corresponding energies of charge transfer (CT) state are compared and analyzed using QC simulation. Moreover, the electron transfer/recombination rates for these interfacial configurations are also studied. From these data, we have elucidated the underlying reason why TTF/TCNQ heterojunction is inadaptable to OPV application. One main reason is that large |ΔGCT| (the absolute value of Gibbs free energy change of CT) forms a large energy barrier, limiting exciton dissociation at the TTF/TCNQ heterojunction, and small |ΔGCR| (the absolute value of Gibbs free energy change of charge recombination) performs the easy recombination to the ground state.
authors.affiliation: Institute of Functional Material Chemistry, Faculty of Chemistry, Northeast Normal University, Changchun 130024, People's Republic of China.
authors.forename: Shuang-Bao
authors.initials: SB
authors.lastname: Li
authors.affiliation: Institute of Functional Material Chemistry, Faculty of Chemistry, Northeast Normal University, Changchun 130024, People's Republic of China.
authors.forename: Yun
authors.initials: Y
authors.lastname: Geng
authors.affiliation: Department of Chemistry, Capital Normal University, Beijing 100048, People's Republic of China.
authors.forename: Yu-Ai
authors.initials: YA
authors.lastname: Duan
authors.affiliation: Department of Chemistry, Faculty of Science, Yanbian University, Yanji 133002, People's Republic of China.
authors.forename: Guang-Yan
authors.initials: GY
authors.lastname: Sun
authors.affiliation: Institute of Functional Material Chemistry, Faculty of Chemistry, Northeast Normal University, Changchun 130024, People's Republic of China.
authors.forename: Min
authors.initials: M
authors.lastname: Zhang
authors.affiliation: Institute of Functional Material Chemistry, Faculty of Chemistry, Northeast Normal University, Changchun 130024, People's Republic of China.
authors.forename: Yong-Qing
authors.initials: YQ
authors.lastname: Qiu
authors.affiliation: Department of Chemistry, Faculty of Science, Yanbian University, Yanji 133002, People's Republic of China.
authors.forename: Zhong-Min
authors.initials: ZM
authors.lastname: Su