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A Nonfullerene Acceptor Containing Rhodanine and Barbituric Acid End Groups for Use in Organic Photovoltaic Devices
Author(s) -
Lim Eunhee
Publication year - 2019
Publication title -
bulletin of the korean chemical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.237
H-Index - 59
ISSN - 1229-5949
DOI - 10.1002/bkcs.11739
Subject(s) - homo/lumo , barbituric acid , acceptor , rhodanine , photochemistry , chemistry , side chain , energy conversion efficiency , organic solar cell , materials science , molecule , optoelectronics , polymer , organic chemistry , physics , condensed matter physics
We synthesized a rod‐shaped asymmetric bithiophene‐based nonfullerene small‐molecule acceptor, ORH‐T2‐OBAR , for organic photovoltaic (OPV) cells. Electron‐withdrawing rhodanine (RH) and barbituric acid (BAR) dye groups with long octyl side chains were asymmetrically introduced at either end. ORH‐T2‐OBAR exhibits thermal stability and solubility sufficient for fabricating OPVs. A blue‐shifted absorption maximum at 440 nm and H ‐type aggregation are observed in the ORH‐T2‐OBAR film compared with ORH‐T2‐OBAR in solution. ORH‐T2‐OBAR has the lowest unoccupied molecular orbital (LUMO) and highest occupied molecular orbital (HOMO) energy levels as low as −3.63 eV and −5.81 eV, respectively, leading to sufficient energy offsets with the PTB7‐Th polymer donor (LUMO = −3.19 eV, HOMO = −5.23 eV) to achieve exciton dissociation. Lastly, an inverted as‐cast device fabricated with PTB7‐Th and ORH‐T2‐OBAR as a donor and an acceptor, respectively, displayed a power conversion efficiency of 0.91%, an open‐circuit voltage of 0.81 V, and an energy loss of 0.78 eV.