Quinoxaline-based cyclo(oligophenylenes)

A series of fully conjugated quinoxaline-based oligophenylene macrocycles is synthesized by Ni0-mediated Yamamoto-type diaryl homocoupling of (fluorinated) 2,3-bis(4'-bromophenyl)quinoxaline precursors. Cyclotrimers and cyclotetramers are obtained as the dominant reaction products. The cyclooligomers are fully characterized, including single-crystal X-ray structures, and their optoelectronic properties are analyzed with respect to possible applications in host-guest chemistry and organic electronics. © 2015 American Chemical Society

Design and Synthesis of Functionalized Regio regular Poly(3-hexylthiophene) based Copolymers and Application in polymer : fullerene Bulk Heterojunction solar cells

set of novel regioregular poly(3-hexylthiophene)-based random copolymers containing varying ratios of ester functionalized alkyl side chains were synthesized using the Rieke method. The percentage of functionalized side chain varied between 10 and 50 mol% for each copolymer. Using post-polymerization reactions, the ester functions in the alkyl side chain were hydrolyzed to yield an alcohol or acid group. These groups are available for further functionalization reactions, so a wide variety of secondary functionalities may be covalently attached to the conjugated polymer. The copolymers were applied in polymer: fullerene bulk heterojunction solar cells (BHJSCs) with [6,6]-phenyl -C61-butyric acid methyl ester (PCBM) as electron acceptor. The influence of side-chain functionalities on absorption, device performance and layer morphology depends on the ratio and nature of the functionalized side chains. For a 9/1 copolymer, containing 10% of functionalized side chains, behaviour and efficiency in BHJSCs comparable to P3HT:PCBM solar cells were observe

Synthesis And Characterization Of A Poly(1,3-dithienylisothianaphthene) Derivative For Bulk Heterojunction Photovoltaic Cells

The synthesis of a poly(1,3-dithienylisothianaphthene) (PDTITN) derivative obtained via oxidative polymerization of 5,6-dichloro-1,2-bis(3'-dodecylthienyl)isothianaphthene is described. PDTITN exhibits a band gap of 1.80-1.85 eV. The redox properties of PDTITN were characterized using cyclic voltammetry and spectroelectrochemistry. Photoexcitation of PDTITN results in photoluminescence (PL) in the near-IR region and the formation of a triplet state. In the presence of a methanofullerene (PCBM) as an electron acceptor, PL and triplet formation of PDTITN are quenched. In photovoltaic devices using blends of the polymer with PCBM, the observed incident-photon-to-collected-electron efficiency (IPCE) up to 24% at 400 nm and the 3 orders of magnitude increase of short circuit current as compared to the polymer alone prove the photoactivity of the PDTITN/PCBM blend in the device.

Ester-functionalized poly(3-alkylthiophene) copolymers : synthesis, physicochemical characterization and performance in bulk heterojunction organic solar cells

The introduction of functional moieties in the donor polymer (side chains) offers a potential pathway toward selective modification of the nanomorphology of conjugated polymer:fullerene active layer blends applied in bulk heterojunction organic photovoltaics, pursuing morphology control and solar cell stability. For this purpose, two types of poly(3-alkylthiophene) random copolymers, incorporating different amounts (10/30/50%) of ester-functionalized side chains, were efficiently synthesized using the Rieke method. The solar cell performance of the functionalized copolymers was evaluated and compared to the pristine P3HT:PCBM system. It was observed that the physicochemical and opto-electronic characteristics of the polythiophene donor material can be modified to a certain extent via copolymerization without (too much) jeopardizing the OPV efficiency, as far as the functionalized side chains are introduced in a moderate ratio