| Summary: | 碩士 === 國立交通大學 === 材料科學與工程學系所 === 102 === In this study, we synthesized three A-D-A typed small molecules, BT-TB3T、DOBT-TB3T and DDBT-TB3T, composed of 2,2’-bithiophene(BT), 4,4'-dioctyl-2,2'-bithiophene(DOBT),and 4,4'-didodecyl-2,2'-bithiophene(DDBT) as central donor core, respectively, terthiophene as bridge, and thiobarbituric acid as electron acceptor. Those molecules display broad absorption width in visible region .By varying alkyl chain, we found that side chain length on the core affect their intermolecular stacking capabilities, thermal properties, and light absorption properties; hence, it also determent the device characteristics. BT-TB3T show strongly intermolecular forces, after annealing with a strong ability to crystallize; besides, the orientation of stacking are face-on and edge-on direction, which is favor morphology for OPVs. The devices incorporated BT-TB3T and PC61BM show highly Jsc (8.44 mAcm-2), and result the highest efficiency (3.8 %).On the contrary, DOBT-TB3T, featuring octyl chains on core, show higher Voc (0.95 V) and less Jsc (7.09 mAcm-2)because of weak intermolecular forces arising from the influence of side chains. On the other hand, DDBT-TB3T which has longest alky chain exhibit poor crystallinity; thus, PCE is just only 1.14% when it was blend with PC61BM.
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