Simultaneous Enhancement of Solar Cell Efficiency
and Photostability via Chemical Tuning of Electron Donating Units
in Diketopyrrolopyrrole-Based Push–Pull Type Polymers
Tae In Ryu
Youngwoon Yoon
Ji-Hoon Kim
Do-Hoon Hwang
Min Jae Ko
Doh-Kwon Lee
Jin Young Kim
Honggon Kim
Nam-Gyu Park
BongSoo Kim
Hae Jung Son
10.1021/ma501300a.s001
https://acs.figshare.com/articles/journal_contribution/Simultaneous_Enhancement_of_Solar_Cell_Efficiency_and_Photostability_via_Chemical_Tuning_of_Electron_Donating_Units_in_Diketopyrrolopyrrole_Based_Push_Pull_Type_Polymers/2252557
We synthesized a series of push–pull-type
copolymers by
copolymerizing an electron-deficient diketopyrrolopyrrole with three
electron-donating benzodithiophene (BDT) moieties. PDPPDTT, which
incorporated a dithienothiophene (DTT), showed a higher power conversion
efficiency (PCE) of 6.11% compared to 3.31% for the BDT-based polymer
(PDPPBDT). PDPPDTBDT, which incorporated a dithienobenzodithiophene
(DTBDT), also exhibited superior performance, with a PCE of 4.75%
although this value was lower than that obtained for PDPPDTT. The
presence of the DTT unit in the polymer backbone lowered the energy
bandgap of the polymer and induced an optimal morphology in the polymer:PC<sub>71</sub>BM blend film, resulting in higher charge carrier generation.
Furthermore, the effectively delocalized frontier orbitals of PDPPDTT
enhanced intermolecular interactions between the polymer chains by
favoring effective π–π stacking, which facilitated
charge carrier transport. By contrast, PDPPDTBDT unexpectedly showed
a low-crystallinity thin film despite its backbone planarity, which
reduced the performance relative to that of PDPPDTT. Importantly,
PDPPDTT exhibited significantly better device stability compared to
the other polymers in a light soaking test due to the much higher
photochemical stability of PDPPDTT. We demonstrated a systematic approach
to simultaneously increasing the photovoltaic performances and device
stability, and we explored the basis for the structure–property
relationship that accompanied such improvements.
2014-09-23 00:00:00
charge carrier generation
PDPPDTT
power conversion efficiency
DTT
BDT
device stability
Solar Cell Efficiency
PDPPBDT
polymer
PDPPDTBDT
performance
charge carrier transport
DTBDT
delocalized frontier orbitals
PCE