Lee, W.-Y.W.-Y.LeeCheng, K.-F.K.-F.ChengWang, T.-F.T.-F.WangWEN-CHANG CHENFENG-YU TSAI2018-09-102018-09-102010http://www.scopus.com/inward/record.url?eid=2-s2.0-73949107374&partnerID=MN8TOARShttp://scholars.lib.ntu.edu.tw/handle/123456789/356563The photovoltaic properties of three fluorene-thiophene-based donor-acceptor copolymers with low band gap and reasonably high hole mobility were studied in copolymer/[6,6]-phenyl-C61-butyric acid methyl ester (PCBM) bulk-heterojunction photovoltaic cells. The copolymers were poly[2,7-(9,9′-dihexylfluorene)-alt-2,3-dimethyl-5,7-dithien-2-yl-quinoxaline] (PFDDTQ) (band gap = 1.94 eV; mobility = 2.83 × 10- 5 cm2 V- 1 s- 1), poly[2,7-(9,9′-dihexylfluorene)-alt-4,7-dithien-2-yl-2,1,3-benzothiadiazole] (PFDTBT) (band gap = 1.82 eV; mobility = 4.71 × 10- 5 cm2 V- 1 s- 1) and poly[2,7-(9,9′-dihexylfluorene)-alt-2,3-dimethyl-5,7-dithien-2-yl-thieno[3,4-b] pyrazine] (PFDDTTP) (band gap = 1.68 eV; mobility = 1.18 × 10- 4 cm2 V- 1 s- 1). The order in the short-circuit current density and power-conversion efficiency of the photovoltaic cells was PFDTBT > PFDDTQ > PFDDTTP, which contradicted the order in the band gap and mobility. The short-circuit current density and power-conversion efficiency (PCE) coincided instead with the order in the mobility of the copolymer/PCBM blend, where the mobility was increased for PFDTBT and PFDDTQ owing to the charge transfer with PCBM, but was decreased for PFDDTTP due to phase separation resulting from the strong intermolecular interactions of PFDDTTP. With its high blended mobility and low band gap, PFDTBT achieved a PCE of 1.1%. © 2009 Elsevier B.V. All rights reserved.Bulk-heterojunction solar cells; Donor-acceptor copolymer; Low band gap[SDGs]SDG7Band gaps; Benzothiadiazoles; Bulk heterojunction; Butyric acids; Donor-acceptor copolymers; Fluorene-thiophene; Fluorenes; Intermolecular interactions; Low band gap; Methyl esters; Photovoltaic property; Power conversion efficiencies; Pyrazines; Quinoxalines; Charge transfer; Conversion efficiency; Copolymerization; Copolymers; Energy gap; Esters; Fatty acids; Heterojunctions; Ion exchange; Organic polymers; Phase separation; Photoelectrochemical cells; Photovoltaic cells; Plastic products; Solar cells; Switching circuits; Thiophene; Hole mobilityjournal article10.1016/j.tsf.2009.07.1252-s2.0-73949107374WOS:000274812800040