Synthesis of new 2, 6-bis(6-fluoro-2-hexyl-2H-benzotriazol-4-yl)-4, 4-bis(2-ethylhexyl)-4H-silolo[3, 2-b:4, 5-b']dithiophene based D-A conjugated terpolymers for photovoltaic application. (20th December 2017)

• Record Type: Journal Article
• Authors: Keshtov, M.L.; Kuklin, S.A.; Khokhlov, A.R.; Konstantinov, I.O.; Nekrasova, N.V.; Xie, Zhi-yuan; Sharma, Ganesh D.
• Is Part Of: Polymer. Volume 133(2017)
• Page Start: 195
• Page End: 204
• Publication Date: 2017-12-20
• Subjects: Conjugated copolymers -- Polymer solar cells -- Solvent additives -- Power conversion efficiency; Polymers -- Periodicals; Polymerization -- Periodicals; Polymères -- Périodiques; Polymérisation -- Périodiques; 547.7
• DOI: 10.1016/j.polymer.2017.11.012
• Languages: English
• ISSNs: 0032-3861

Abstract

Abstract: Two D1-A-D2-A conjugated terpolymers with same A (fluorinated benzotriazole, fBTz), D2 (dithienosilole, DTS) and different D1 (bis(undecyl)benzo[2, 1-b:3, 4-b']dithiophene forP1 and didodecyloxy-benzo[1, 2-b:4, 5-b']dithiophene forP2 ) were synthesized and their optical and electrochemical properties were investigated. Compared toP1, theP2 with didodecyloxy side chains in benzodithiophene showed strong interchain π-π interaction, more redshifted absorption spectrum and higher molar extinction coefficient. The X-ray diffraction results indicated their excellent crystallinity and molecular stacking features, especiallyP2 containing didodecyloxy side chains in BDT. These two terpolymers were used as donor along with PC71 BM for the fabrication of bulk heterojunction polymer solar cells. After the optimization of active layers, i.e. weight ratios of terpolymer to PC71 BM and concentration of solvent additive (DIO) in the host solvent, the resultant polymer solar cells showed overall power conversion efficiency of 6.95% (Jsc = 12.23 mA/cm 2, Voc = 0.93 V and FF = 0.61) and 8.14% (Jsc = 14.08 mA/cm 2, Voc = 0.85 V and FF = 0.68) forP1 andP2 based bulk heterojunction active layers, respectively. The higher power conversion efficiency ofP2 based polymer solar cell thanP1 based counterpart, may be attributed to the more exciton dissociation, better nanoscale morphology and higher hole mobility inP2 :PC71 BM active layer thanP1 :PC71 BM. Graphical abstract: After the optimization of active layer, the overall PCE of 6.95 % and 8.14 % for P1:PC71 BM and P2:PC71 BM based PSCs, respectively. Highlights: Two D1-A-D2-A conjugated copolymers were designed and characterized. These two copolymers consisted of same acceptor and different donors. High power conversion efficiency of 8.14% was achieved after the optimization of active layer.