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A series of electron-acceptor polymers, copolymers and blends were used in all-polymer BHJ photodetectors and the effect of acceptor compositions on the key device parameters of dark current density and photocurrent was investigated. Compared with acceptor polymers and polymer blends, the devices based on acceptor copolymer showed lowered dark current and higher photocurrent, due to optimal molecular...
In order to investigate the effect of the ratio of donor (D) and acceptor (A) in conjugated D-A polymers on the photovoltaic properties and photodetector performance, a series of polymers containing a weak electron donor of thiophene (T) and a strong electron acceptor of pyrrolo [3,4-c]pyrrole-1,4-dione (DPP) were designed and synthesized. Five polymers P1–P5 were obtained with different D/A (T/DPP)...
A weak electron acceptor, 4,9-bis(5-bromothiophen-2-yl)-2-(2-ethylhexyl)-benzo[f]isoindole-1,3-dione (BIDO) was designed and synthesized. Polymer P1 derived from BIDO and 9,9-dioctylfluorene-2,7-diboronic acid bis(1,3-propanediol) ester by Suzuki cross-coupling reaction has a band gap of 2.41 eV. To expand the absorption range, a different amount of BIDO was copolymerized with a diketopyrrolopyrrole...
A strong bicyclic guanidine base, 1,5,7-triaza-bicyclo[4.4.0]dec-5-ene (TBD), is photo-generated from its tetraphenylborate salt (TBD·HBPh 4 ) and can effectively catalyze the transesterification reaction between the ester and hydroxy groups in polymers. Accordingly, with TBD·HBPh 4 as a photobase generator, a water-soluble polymer blend, namely poly(1-vinylpyrrolidone-co-2-dimethylaminoethyl...
In this work, using a fluorescent poly(phenylene ethynylene) containing the rigid pentiptycene and large cholesteryl ester pendent groups, the fluorescence quenching properties of the polymer thin films in response to vapor of 2,4-dinitrotulene (DNT) have been investigated by varying the film thickness, applying an undercoating and blending with another polar polymer. A significant change in fluorescence...
A new polymerization in the melt of salicylic acid has been developed for the one-step synthesis of polyimides from various diamines and dianhydrides. The polymerization is carried out in high solid content up to 40–50wt/v% at 200°C and affords the completely cyclized polyimides with high molecular weights in 1–2h. The preliminary studies on some of the polymerization variables (e.g., concentration...
The crystalline conformations of perylene polyimides (PPIs), with alkyl spacers varying in length from C 3 to C 12 are discussed. Although modeling of single chains would suggest the possibility that those with odd number of CH 2 groups adopt a flat helical shape, X-ray diffraction suggests that the chains with odd and even spacers have the same conformation, due to the necessity...
A unique crystallization and melting behavior of a novel semicrystalline polyimide derived from 3,3′,4,4′-biphenyltetracarboxylic dianhydride and 1,4-bis(3-aminopropyl)piperazine were studied by differential scanning calorimetry (DSC) with and without temperature modulation and wide-angle X-ray diffraction (WAXD). Polymer samples isolated from a chloroform solution showed melting transitions in the...
Polyacrylonitrile(PAN) is used to study the effect of surface charge on electrospinning by adding LiCl. The theoretical analysis shows that the relationship between radius r of jet and the axial distance z from nozzle follows an allometric law in the form r∼z −0.5 in case of full surface charge, and the scaling exponent becomes larger for partly charged fibers in electrospinning.
Polymers containing the pendant propargyl groups can be effectively crosslinked upon UV irradiation in the presence of a small amount of W(CO) 6 . The alkyne–tungsten carbonyl complex was formed initially as evident by IR spectroscopy, which was involved in the subsequent crosslinking reaction. Analyses by UV, IR, and 13 C NMR CP/MAS spectroscopic methods confirmed the polymer crosslinking...
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