TY - JOUR
T1 - Temperature-Modulated Optimization of High-Performance Polymer Solar Cells Based on Benzodithiophene-Difluorodialkylthienyl-Benzothiadiazole Copolymers
T2 - Aggregation Effect
AU - Huang, Lanqi
AU - Zhang, Guangjun
AU - Zhang, Kai
AU - Peng, Qiang
AU - Wong, Ricky M S
N1 - This work was supported by the Institute of Molecular Functional Materials, a grant from the University Grants Committee, Areas of Excellence Scheme (AoE/P-03/08), the NSFC (51573107, 91633301 and 21432005) and the Foundation of State Key Laboratory of Polymer Materials Engineering (sklpme2017-2-04).
PY - 2019/6/25
Y1 - 2019/6/25
N2 - A novel series of low band gap donor-acceptor copolymers derived from 4,5-bis(2-ethylhexyloxy)-benzo[2,1-b:3,4-b′]dithiophene (BDT) and 5,6-difluoro-4,7-bis(4-alkylthien-2-yl)benzo[c][1,2,5]thiadiazole bearing various alkyl side chains, such as PffBB-n (n = 10, 12, 14, and 16), were developed for high-performance bulk-heterojunction (BHJ) polymer solar cells (PSCs). PffBB-n exhibited not only strong and wide absorption but also controllable aggregation behavior in solution and thin films, in which aggregation behavior was greatly influenced by the length of alkyl side chains attached, temperature applied, and solvent used. Aggregation-induced spectral broadening further extended the absorption cut-off to ∼780 nm in thin films, leading to a narrow optical band gap of ∼1.6 eV. Because of the strong aggregation strength, PffBB-n equipped with long alkyl side chains shows enhanced ordered molecular packing and good crystallinity as revealed by X-ray diffraction studies. In addition, temperature-dependent aggregation of the PffBB-n:PC71BM blend was investigated and optimized in the PSC fabrication. PSCs fabricated with the PffBB-n:PC71BM blend, conducted at 80 °C optimized coating temperature, showed relatively high power conversion efficiency (PCE) ranging from 8.22 to 9.93%. The well-ordered BHJ film morphology of the PffBB-14:PC71BM blend led to superior balanced charge carrier mobility, good exciton dissociation, and the least recombination loss and hence PffBB-14-based PSC reached the highest photovoltaic performance with a PCE of 9.93%, a Voc of 0.92 V, a Jsc of 16.77 mA cm-2 and, a FF of 64.36%. Our results demonstrated that the synergetic effect of alkyl side chain modification and processing temperature modulation to control aggregation provides practical and powerful tools to optimize the absorption broadening and optoelectronic properties of an active layer in a BHJ PSC, thus enhancing its ultimate performance.
AB - A novel series of low band gap donor-acceptor copolymers derived from 4,5-bis(2-ethylhexyloxy)-benzo[2,1-b:3,4-b′]dithiophene (BDT) and 5,6-difluoro-4,7-bis(4-alkylthien-2-yl)benzo[c][1,2,5]thiadiazole bearing various alkyl side chains, such as PffBB-n (n = 10, 12, 14, and 16), were developed for high-performance bulk-heterojunction (BHJ) polymer solar cells (PSCs). PffBB-n exhibited not only strong and wide absorption but also controllable aggregation behavior in solution and thin films, in which aggregation behavior was greatly influenced by the length of alkyl side chains attached, temperature applied, and solvent used. Aggregation-induced spectral broadening further extended the absorption cut-off to ∼780 nm in thin films, leading to a narrow optical band gap of ∼1.6 eV. Because of the strong aggregation strength, PffBB-n equipped with long alkyl side chains shows enhanced ordered molecular packing and good crystallinity as revealed by X-ray diffraction studies. In addition, temperature-dependent aggregation of the PffBB-n:PC71BM blend was investigated and optimized in the PSC fabrication. PSCs fabricated with the PffBB-n:PC71BM blend, conducted at 80 °C optimized coating temperature, showed relatively high power conversion efficiency (PCE) ranging from 8.22 to 9.93%. The well-ordered BHJ film morphology of the PffBB-14:PC71BM blend led to superior balanced charge carrier mobility, good exciton dissociation, and the least recombination loss and hence PffBB-14-based PSC reached the highest photovoltaic performance with a PCE of 9.93%, a Voc of 0.92 V, a Jsc of 16.77 mA cm-2 and, a FF of 64.36%. Our results demonstrated that the synergetic effect of alkyl side chain modification and processing temperature modulation to control aggregation provides practical and powerful tools to optimize the absorption broadening and optoelectronic properties of an active layer in a BHJ PSC, thus enhancing its ultimate performance.
UR - http://www.scopus.com/inward/record.url?scp=85067915722&partnerID=8YFLogxK
U2 - 10.1021/acs.macromol.9b00682
DO - 10.1021/acs.macromol.9b00682
M3 - Journal article
AN - SCOPUS:85067915722
SN - 0024-9297
VL - 52
SP - 4447
EP - 4457
JO - Macromolecules
JF - Macromolecules
IS - 12
ER -
