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Here, the synthesis, characterization, and photovoltaic properties of four new donor-acceptor copolymers are reported. These copolymers are based on 4,4-difl uoro-cyclopenta[2,1-b:3,4-b′] dithiophene as an acceptor unit and various donor moieties: 4,4-dialkyl derivatives of 4H-cyclopenta[2,1-b:3,4-b′]dithiophene and its silicon analog, dithieno[3,2-b:2′,3′-d]-silol. These copolymers have an almost identical bandgap of 1.7 eV and have a HOMO energy level that varies from −5.34 to −5.73 eV. DSC and X-ray diffraction (XRD) investigations reveal that linear octyl substituents promote the formation of ordered layered structures, while branched 2-ethylhexyl substituents lead to amorphous materials. Polymer solar cells based on these copolymers as donor and PC 61 BM as acceptor components yield a power conversion effi ciency of 2.4%.

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and recombination loss mechanisms for these oligomers. This study not only revealed the importance of integrated alkyl chain engineering on gaining morphological control for high performance OSCs, but also exhibited a clear correlation between molecular ordering and charge carrier mobility respective to carrier dynamics. These results outline a detailed strategy towards a rather complete characterization and optimization methodology for organic photovoltaic devices, thereby paving the way for researchers to easily find the performance parameters adapted for widespread applications.

In this work, we were the first to show the possibility of synthesizing polydimethylsiloxanes (PDMSs) with azidopropyl-functional groups at the silicon atom by the classical methods for PDMS synthesis, that is, ring-opening polymerization (ROP) and catalytic rearrangement of siloxanes in the presence of a strong acid (CF3SO3H). The suggested method was used to obtain PDMSs containing azidopropyl-functional groups at both ends of the polymer chain (telechelics) as well as PDMSs with irregular structures containing different fractions (5–50%) of azidopropyl-functional groups in the main polymer chain. The suggested method also proved to be efficient for synthesizing PDMSs containing both azidopropyl- and hydridosilyl-functional groups simultaneously. As a result, PDMSs with different mutual arrangements of two types of functional groups along the PDMS chain were obtained. The method for the catalytic rearrangement of low-molecular-weight siloxanes that we used made it possible to obtain azidopropyl-functional PDMSs in a wide range of molecular weights from 2000 to 88,000 according to gel permeation chromatography (GPC) data. The possibility of further modification of the resulting azidopropyl-functional PDMS, as well as multifunctional PDMSs containing azidopropyl- and hydridosilyl-functional groups simultaneously, by azide-alkyne cycloaddition reactions was demonstrated. The polymers obtained were characterized by 1H and 29Si NMR spectroscopy and by GPC.