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A series of donor–acceptor (D–A) polymers ( P1 – P3 ) based on benzodithiophene (BDT) and electron-accepting benzotriazole (BTZ) units containing thiophene linkers with/without alkyl side-chains were designed and synthesized via Stille coupling polymerization method. The effects of polymers with multiple fluorinated BTZ groups on their thermal, optical, electrochemical, and photovoltaic properties were investigated. These polymers possessed the highest occupied molecular orbital (HOMO) levels ranged −5.38 to −5.6 eV and the lowest unoccupied molecular orbital (LUMO) levels ranged −3.55 to −3.57 eV, which covered broad absorption ranges with low optical bandgaps. The bulk heterojunction (BHJ) polymer solar cell (PSC) devices containing an active layer of D-A polymers blended with different weight ratios of electron-acceptor [6,6]-phenyl-C 71 -butyric acid methyl ester (PC 71 BM) were explored under 100 mW cm −2 of AM 1.5 white-light illumination, where the maximum power conversion efficiency (PCE) value of 3% (with J sc = 7.70 mA/cm 2 , FF = 54.04, and V oc = 0.72 V) was obtained in the PSC device consisting of polymer P3 . [ABSTRACT FROM AUTHOR]

A series of donor-acceptor (D-A) type low-bandgap polymers containing the terthiophene and thieno[3,4- b]thiadiazole units in the main chain but different numbers of identical side chains are designed and synthesized in order to study the effect of side chain on the polymer properties and optimize the performance of polymer photodetectors. Variation in the side chain content can influence the polymer solubility, molecular packing, and film morphology, which in turn affects the photodetector performance, particularly with regard to the photoresponsivity and dark current. X-ray diffraction patterns indicate that molecular ordering increases with more side chains. Atomic force microscopy shows that appropriate morphology of the active layer in the polymer photodetector is necessary for high photocurrent and low dark current. Using BCP as a hole blocking layer (10 nm), the photodetector based on P4 exhibits the optimized performance with specific detectivity of 1.4 × 1012 Jones at 800 nm, which is among the best reported values for polymer photodetectors and even comparable to that of a silicon photodetector. [ABSTRACT FROM AUTHOR]

Highlights: [•] Two techniques for improved PbS quantum dot (QD) solar cells were examined. [•] Plasma was applied to QD film for removing surface organic ligands. [•] A low-bandgap polymer was then deposited on the QD film as a hole-transporting layer. [•] The bilayer heterojunction device showed broad-range absorption and favorable charge transfer. [•] The efficiency was increased from 0.7% to 1.76% by applying the two novel methods. [ABSTRACT FROM AUTHOR]

The concept of introducing π-conjugated but anti-aromatic repeating units into conjugated polymers has been explored. The thermal stability, optical and electrochemical properties of dithieno[ a, e]pentalenes (DTP) based polymers have been studied. The effect of introducing electron withdrawing repeating units into DTP based polymer on the physical properties of polymer has also been investigated. The new polymers showed broad absorption in visible and near-infrared region. [ABSTRACT FROM AUTHOR]

Abstract: New thieno[3,4-b]thiophene derivatives were prepared via a short and versatile synthetic route. Electrochemical studies of 2-heptenylthieno[3,4-b]thiophene, 2-styrylthieno[3,4-b]thiophene, and 2-phenyl-3-(thieno[3,4-b]thiophene-2-yl)acrylonitrile and the corresponding polymers revealed that raising the HOMO and lowering the LUMO can be attained by functionalizing thieno[3,4-b]thiophene with aromatic resonance-enhancing and electron-withdrawing groups. The bandgap of resulting polymers varied from 0.78 to 1.0eV, indicating that poly(2-phenyl-3-(thieno[3,4-b]thiophene-2-yl)acrylonitrile) is one of the lowest bandgap polymers ever reported. [Copyright &y& Elsevier]