New ultra low bandgap thiadiazolequinoxaline-based D-A copolymers for photovoltaic applicationsстатья
Статья опубликована в высокорейтинговом журнале
Информация о цитировании статьи получена из
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Статья опубликована в журнале из списка Web of Science и/или Scopus
Дата последнего поиска статьи во внешних источниках: 28 октября 2016 г.
Аннотация:In this communication, we designed two low bandgap D-A copolymers with same fluorinated thiadiazoloquinoxaline
(TDQ) as acceptor and different donor units benzo[2,1-b;3,4-b0]dithiophene (P1) and
benzo[1,2-b:4,5-b0]dithiophene (P2). P1 and P2 exhibit broad absorption profiles covering from 350 nm
to 1150 nm and 350e950 nm, respectively with optical bandgaps of 1.06 eV and 1.18 eV, respectively.
Both copolymers showed deep highest occupied molecular orbitals (HOMO), i.e. 5.38 eV and 5.26 eV,
for P1 and P2. Their photovoltaic properties were evaluated using conventional devices with a structure
of ITO/PEDOT:PSS/copolymer:PC71BM/Al. After the optimizations of the copolymer to PC71BM weight
ratios, and concentration of the solvent additive (DIO), the devices showed overall power conversion
efficiencies of 4.03% and 5.42% for the P1 and P2 based devices, respectively. The higher value of PCE of
the P2 based device is attributed to the higher values of Jsc and FF, that is related to the higher hole
mobility and better exciton dissociation efficiency. Although the PCEs of these devices are moderate,
these ultra low band gap copolymers can be used for their potential application in tandem polymers
solar cells. Finally, methanol treatment of the active layer was adopted to increase the PCE of the
P2:PC71BM based polymer solar cells that resulted in an improved PCE up to 6.93%.