Synthesis and photovoltaic properties low bandgap D-A copolymers based on fluorinated thiadiazoloquinoxalineстатья
Статья опубликована в высокорейтинговом журнале
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Дата последнего поиска статьи во внешних источниках: 18 апреля 2017 г.
Аннотация:In this communication, we report the design a low bandgap D-A copolymer consist of fluorinated
thiadiazoloquinoxaline (TDQ) as strong acceptor and benzothiophene (BT), denoted as P(ffFlTDQx-BT)
exhibit broad absorption profile covering from 350 nm to 1000 nm with optical bandgap of 1.26 eV.
P(ffFlTDQx-BT) showed highest occupied molecular orbital (HOMO) energy level of 5.46 eV which is
deeper than that for nonfluorinated counterpart copolymer. The photovoltaic properties were evaluated
using conventional devices with a structure of ITO/PEDOT:PSS/P(ffFlTDQx-BT):PC71BM/Al. After the
optimizations of the P(ffFlTDQx-BT) to PC71BM weight ratios, and concentration of the solvent additive
(DIO), the devices showed overall power conversion efficiency of 7.27%. The higher value of PCE of this
device is higher than that of nonfluorinated copolymer (5.80%) is attributed to the higher values of both
Jsc and FF, related to the higher hole mobility and better exciton dissociation efficiency. Moreover,
employing a low boiling point solvent additive, i.e. o-chlorobenzaldehyde (CBA) (boiling point 132 C) for
active layer deposition and after the optimization of concentration of CBA, the resulted PSC showed
overall PCE of 8.10%, which is higher than the PSC based on active processed with DIO/CB, related to the
better balanced charge transport, induced by the fast removal of residues of solvent. To our best of our
knowledge, PCE of 8.10% is also the highest for the PSCs with low bandgap of below 1.30 eV.