Browsing by Author "Huang, Sin-Hong"

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Polymorphisms and morphological studies of a difluorobenzothiadiazole conjugated copolymer with 7.8% polymer solar cell efficiency
(2015-01-01)
Huang, Chi-Feng
;
Chang, Jen-Yun
;
Huang, Sin-Hong
;
Wu, Kuan-Yi
;
Jheng, Jyun-Fong
This study presents the structural characterization of a 5,6-difluorobenzo- 2,1,3-thiadiazole (FBT)-quaterthiophene (Th-4) alternating copolymer (PTh4FBT) and how the crystalline nature of PTh4FBT affects the PTh4FBT-PC71BM morphology and the device performances. The single crystal structure of 5,6-difluoro-4,7-di(thiophen-2-yl) benzothiadiazole (Th2FBT) first confirms the low conformational preference of the FBT containing molecule. Since the crystallization process does not assist in unifying the conformation of Th2FBT, both intrachain conformation and interchain c-shifts in the crystalline state of PTh4FBT have to be scrutinized. By comparing the 2D WAXS pattern of PTh4FBT and the simulated patterns generated from Cerius(2) molecular modeling, it was found that the diffraction pattern generated from the lattice containing PTh4FBT with anti-conformation and limited interchain c-shift matches best with the experimental one. The face-to-face interchain stacking of PTh4FBT rendered strong crystalline nature to the polymer and caused large segregation in the PTh4FBT-PC71BM blend system, which was indicated by the TEM and GI WAXS morphological studies. The aggregation size was reduced via the use of the 1-chloronaphthalene additive. The optimized morphology led to improved J(sc) and FF. The single-junction PTh4FBT-PC71BM based polymer solar cells deliver a high PCE of 7.75% with a V-oc of 0.76 V, a J(sc) of 14.36 mA cm(-2), and a FF of 71.0%.
Stepwise Structural Evolution of a DTS-F2BT Oligomer and Influence of Structural Disorder on Organic Field Effect Transistors and Organic Photovoltaic Performance
(2016-12-27)
Huang, Chi-Feng
;
Huang, Sin-Hong
;
Hsieh, Chou-Ting
;
Chao, Yi-Hsiang
;
Li, Chia-Hua
An A-D-A oligomer, DTS(F2BT)(2), was synthesized; its structural evolution was studied with DSC, POM, 2D-WAXD, and in-situ GI-XRD. The structural evolution of DTS(F2BT)(2) is stepwise and kinetically slow. Both rapid drying and the presence of PC71BM trapped DTS(F2BT)(2) in a less ordered nematic (N) phase. PDMS-assisted crystallization enabled a pristine DTS(F2BT)(2) thin film to attain a more ordered equilibrium phase, and enhanced the OFET mobility of DTS(F2BT)(2). In OPV devices, DIO additive drove the DTS(F2BT)(2) domains in the DTS(F2BT)(2):PC71BM blended film from the N phase toward the equilibrium phase, and resulted in enhanced OPV performances. These results reveal the slow ordering process of the A-D-A oligomer, and the importance of monitoring the degree of structural evolution of the active thin films in organic optoelectronics.