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Kinetics of UV curable alkyl 3-mercaptopropionate-vinyl silizane

SONG Jiale, CHEN Lixin, WANG Yazhou, CHEN Weiwei, WANG Rumin

《化学科学与工程前沿（英文）》 2008年第2卷第4期页码 390-395 doi: 10.1007/s11705-008-0080-6

摘要： Photopolymerization of vinyl-containing liquid silizane preceramic monomers copolymerized with thiol monomers, based on a step-growth radical polymerization mechanism, is a novel, rapid, inexpensive and simple technique for producing preceramic structures from liquid precursors. The kinetics of alkyl 3-mercptopropionate-vinyl silizane under UV irradiation is investigated by using real-time Fourier transform infrared (FT-IR) and photo-differential scanning calorimetry (photo-DSC). The experimental results show preliminarily that: (1) about 80% conversion of vinyl group has been achieved in the presence of a low concentration photoinitiator under UV irradiation; (2) by increasing the functionalities of the thiol group, the peak rate of copolymerization increases and the final conversion of the vinyl group decreases; (3) the copolymerization is primarily a bimolecular radical termination process; (4) the copolymerization is first-order, i.e., its rate is proportional to the vinyl group concentration and independent of the concentration of thiol group.

关键词： step-growth irradiation bimolecular preceramic concentration photoinitiator

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Effects of BTA2 as the third component on the charge carrier generation and recombination behavior of PTB7:PC

Leijing Liu, Hao Zhang, Bo Xiao, Yang Liu, Bin Xu, Chen Wang, Shanpeng Wen, Erjun Zhou, Gang Chen, Chan Im, Wenjing Tian

《化学科学与工程前沿（英文）》 2021年第15卷第1期页码 127-137 doi: 10.1007/s11705-020-1936-7

摘要： Effects of a benzotriazole (BTA)-based small molecule, BTA2, as the third component on the charge carrier generation and recombination behavior of poly[[4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b']dithiophene-2,6-diyl][3-fluoro-2-[(2-ethylhexyl)carbonyl]thieno[3,4-b]thiophenediyl]] (PTB7):[6,6]-phenyl-C -butyric acid methyl ester (PC BM) organic solar cells (OSCs) were investigated by optical simulation of a transfer matrix model (TMM), photo-induced charge extraction by linearly increasing voltage (photo-CELIV) technique, atomic force microscope (AFM), and the Onsager–Braun model analysis. BTA2 is an A A D A A -type non-fullerene small molecule with thiazolidine-2,4-dione, BTA, and indacenodithiophene as the terminal acceptor (A ), bridge acceptor (A ), and central donor (D), respectively. The short-circuit current density of the OSCs with BTA2 can be enhanced significantly owing to a complementary absorption spectrum. The optical simulation of TMM shows that the ternary OSCs exhibit higher internal absorption than the traditional binary OSCs without BTA2, resulting in more photogenerated excitons in the ternary OSCs. The photo-CELIV investigation indicates that the ternary OSCs suffer higher charge trap-limited bimolecular recombination than the binary OSCs. AFM images show that BTA2 aggravates the phase separation between the donor and the acceptor, which is disadvantageous to charge carrier transport. The Onsager-Braun model analysis confirms that despite the charge collection efficiency of the ternary OSCs being lower than that of the binary OSCs, the optimized photon absorption and exciton generation processes of the ternary OSCs achieve an increase in photogenerated current and thus improve power conversion efficiency.

关键词： third component organic solar cells charge carrier generation charge carrier recombination bimolecular recombination