TY - JOUR
T1 - Side-chain engineering for fine-tuning of energy levels and nanoscale morphology in polymer solar cells
AU - Lee, Jaewon
AU - Kim, Min
AU - Kang, Boseok
AU - Jo, Sae Byeok
AU - Kim, Heung Gyu
AU - Shin, Jisoo
AU - Cho, Kilwon
PY - 2014/7/15
Y1 - 2014/7/15
N2 - A series of four polymers containing benzo[1,2-b:4,5-b']dithiophene (BDT) and 5,6-difluoro-4,7-diiodobenzo[c][1,2,5]thiadiazole (2FBT), PBDT2FBT, PBDT2FBT-O, PBDT2FBT-T, and PBDT2FBT-T-O, are synthesized with their four different side chains, alkyl-, alkoxy-, alkylthienyl-, and alkoxythienyl. Experimental results and theoretical calculations show that the molecular tuning of the side chains simultaneously influences the solubilities, energy levels, light absorption, surface tension, and intermolecular packing of the resulting polymers by altering their molecular coplanarity and electron affinity. The polymer solar cell (PSC) based on a blend of PBDT2FBT-T/[6,6]-phenyl-C 71-butyric acid methyl ester (PC71BM) exhibits the best photovoltaic performance of the four PBDT2FBT derivatives, with a high open-circuit voltage of 0.98 V and a power conversion efficiency of 6.37%, without any processing additives, post-treatments, or optical spacers. Furthermore, PBDT2FBT-T-O, which has a novel side chain alkoxythienyl, showed promising properties with the most red-shifted absorption and strong intermolecular packing property in solid state. This study provides insight into molecular design and fabrication strategies via structural tuning of the side chains of conjugated polymers for achieving highly efficient PSCs.
AB - A series of four polymers containing benzo[1,2-b:4,5-b']dithiophene (BDT) and 5,6-difluoro-4,7-diiodobenzo[c][1,2,5]thiadiazole (2FBT), PBDT2FBT, PBDT2FBT-O, PBDT2FBT-T, and PBDT2FBT-T-O, are synthesized with their four different side chains, alkyl-, alkoxy-, alkylthienyl-, and alkoxythienyl. Experimental results and theoretical calculations show that the molecular tuning of the side chains simultaneously influences the solubilities, energy levels, light absorption, surface tension, and intermolecular packing of the resulting polymers by altering their molecular coplanarity and electron affinity. The polymer solar cell (PSC) based on a blend of PBDT2FBT-T/[6,6]-phenyl-C 71-butyric acid methyl ester (PC71BM) exhibits the best photovoltaic performance of the four PBDT2FBT derivatives, with a high open-circuit voltage of 0.98 V and a power conversion efficiency of 6.37%, without any processing additives, post-treatments, or optical spacers. Furthermore, PBDT2FBT-T-O, which has a novel side chain alkoxythienyl, showed promising properties with the most red-shifted absorption and strong intermolecular packing property in solid state. This study provides insight into molecular design and fabrication strategies via structural tuning of the side chains of conjugated polymers for achieving highly efficient PSCs.
KW - alkoxythienyl side chains
KW - conjugated polymers
KW - morphology
KW - organic solar cells
KW - side-chain engineering
UR - http://www.scopus.com/inward/record.url?scp=84904739722&partnerID=8YFLogxK
U2 - 10.1002/aenm.201400087
DO - 10.1002/aenm.201400087
M3 - Article
AN - SCOPUS:84904739722
SN - 1614-6832
VL - 4
JO - Advanced Energy Materials
JF - Advanced Energy Materials
IS - 10
M1 - 1400087
ER -