1304773-89-4Relevant articles and documents
A comparative study of the effect of fluorine substitution on the photovoltaic performance of benzothiadiazole-based copolymers
Wang, Tzong-Liu,Yang, Chien-Hsin,Chuang, Yao-Yuan
, p. 47676 - 47686 (2016)
Two conjugated alternating copolymers to be used as the donor materials of the active layers in polymer solar cells have been designed and synthesized via a Stille coupling reaction. The alternating structure consisted of 4,8-bis((2-ethylhexyl)oxy)benzo[1,2-b:4,5-b′]dithiophene (BDT) as the donor unit and benzo[c][1,2,5]thiadiazole (BT) or fluorinated benzo[c][1,2,5]thiadiazole (FBT) as the acceptor unit, along with a thiophene group as the π-bridge between the donor and acceptor units. Since the donor units have attached alkoxy pendant chains, both polymers were soluble in common organic solvents. UV-vis spectra of both copolymers exhibited broad absorption bands in the range of 325-900 and 380-900 nm, respectively, and corresponding low band gaps of 1.82 and 1.80 eV. After fluorination of the BT unit, the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energy levels of the polymer were lowered and estimated to be -5.51 and -3.71 eV, respectively. It was found that substitution of an F atom into the BT units facilitated the intramolecular charge transfer. In comparison with the nonfluorinated polymer, the photovoltaic performance of the fluorinated polymer was significantly improved due to the enhanced Jsc and Voc. Based on the ITO/PEDOT:PSS/polymer:PC61BM/LiF/Al device structure, the optimal device efficiency was obtained from a device with a blend of PBDTFBT and PC61BM at a weight ratio of 1:1. For this blend ratio, the values of Jsc and power conversion efficiency (PCE) obtained at room temperature are 7.98 mA cm-2 and 3.62%, respectively, under the illumination of AM 1.5 (100 mW cm-2).
5,6-Difluorobenzothiadiazole and silafluorene based conjugated polymers for organic photovoltaic cells
Li, Guangwu,Kang, Chong,Gong, Xue,Zhang, Jicheng,Li, Weiwei,Li, Cuihong,Dong, Huanli,Hu, Wenping,Bo, Zhishan
, p. 5116 - 5123 (2014/07/07)
To achieve 5,6-difluorobenzothiadiazole and 2,7-linked silafluorene based soluble conjugated polymers, flexible side chains were attached at different positions of the conjugated polymers. Three soluble polymers PSiF-D(OT)DFBT, PSiF-TTDFBT, and PDOSiF-DTDFBT were prepared and used as donor materials for polymer solar cells. PSiF-D(OT)DFBT exhibits a band gap of 2.06 eV with a deep HOMO of -5.64 eV. PSiF-TTDFBT shows a band gap of 1.75 eV with the HOMO of -5.23 eV. PDOSiF-DTDFBT is of a band gap of 1.86 eV with the HOMO level of -5.37 eV. Among these three polymers, PDOSiF-DTDFBT shows the highest field effect transistor (FET) hole mobility up to 3.31 × 10-2 cm2 V-1 s-1, PDOSiF-DTDFBT:PC71BM blend films show the highest SCLC mobility up to 5.10 × 10-4 cm2 V-1 s-1, and polymer solar cells (PSCs) with the blend of PDOSiF-DTDFBT:PC71BM (1:1, by weight) as the active layer gave a power conversion efficiency (PCE) of 4.03% with an open circuit voltage (V oc) of 0.73 V, a short circuit current (Jsc) of 8.55 mA cm-2, and a fill factor (FF) of 0.65. Our studies also reveal the structure-property relationship of 2,7-linked silafluorene and 5,6-difluorobenzothiadiazole based conjugated polymers.
Facile synthesis of fluorine-substituted benzothiadiazole-based organic semiconductors and their use in solution-processed small-molecule organic solar cells
Cho, Nara,Ko, Jaejung,Song, Kihyung,Lee, Jae Kwan
, p. 11433 - 11439,7 (2012/12/12)
A facile new protocol for the synthesis of iodinated derivatives of fluorinated benzothiadiazoles is demonstrated for the production of p-type semiconducting materials. The newly synthesized small-molecule compounds bis[TPA-diTh]-MonoF-BT and bis[TPA-diTh]-DiF-BT exhibited a power conversion efficiency of 2.95 % and a high open-circuit voltage of 0.85 V in solution-processed small-molecule organic solar cells. A facile new protocol was developed for synthesis of iodinated derivatives of fluorinated benzothiadiazoles as precursors for fluorine-substituted benzothiadiazole-based organic semiconductors 2 and 3, which exhibit enhanced intramolecular charge transfer compared to unfluorinated analogue 1 and hence improved photovoltaic performance in small-molecule organic solar cells (see figure). Copyright