Anthracene‐containing PPE‐PPV copolymers: Effect of side‐chain nature and length on photophysical and photovoltaic properties

Abstract

High‐molecular weight anthracene containing poly(p‐phenylene‐ethynylene)‐alt‐poly(p‐phenylene‐vinylene) (PPE‐PPV) copolymers bearing linear and/or branched alkyl side chains have been synthesized and investigated for use in polymer–fullerene bulk heterojunction solar cells. By variation of the nature and length of alkyl side chains the ordering in thin films could be tuned. Besides the basic photophysical characterization, small‐angle X‐ray scattering on extruded fibers and cyclovoltammetry measurements are reported. The photovoltaic characterization indicates that improved ordering due to linear side chains on the arylene–ethynylene segment as well as lower side‐chain volume fraction yield higher photocurrents. Power conversion efficiencies of nearly 2.5% are reported for the best devices with a polymer:fullerene composition of 1:1 by weight. IV‐characteristics of partly optimized photovoltaic devices based on [6,6]‐phenyl C61 butyric acid methyl ester (PCBM) blends with a blending ratio of 1:1 under solar simulator illumination.

Alkoxy-substituted poly(arylene-ethynylene)-alt-poly(arylene-vinylene)s: synthesis, electroluminescence and photovoltaic applications

“…This can be ascribed to an extended donoracceptor interfacial area, which was evidenced by AFM topology pictures showing a constant reduction of the nanoscale cluster size of the active layer from 38a through 38b to 38c. 28 Systematic studies carried out with anthracene-containing polymers AnE-PV 43,51,68,69 demonstrated the same trend observed with polymers 31a-d with respect to the V OC (Table 4). It increases with decreasing side chain bulkiness.…”

“…Photovoltaic parameters of polymers AnE-PV together with their pp-stacking distance, d pp , and hole mobility, m hole , obtained using the CELIV technique Active layer film thicknesses $150 nm 43,51,68,69. units (inducing backbone coplanarity) which are mostly substituted with branched 2-ethylhexyl side chains (presumably reducing the stacking ability).…”

Improvement of photovoltaic performance by ternary blending of amorphous and semi-crystalline polymer analogues with PCBM

“…This is in good agreement with earlier studies conducted on regio-regular and regio-random P3HT, accordingly. 61,70 Both polymers exhibit comparably low open-circuit voltages (V OC ) in the binary blends. The open-circuit voltage of the ternary blends increased progressively with the concentration of amorphous AnE-PVba up to 50 wt% and decreased thereaer again for higher concentrations, indicating losses due to increased charge recombination.…”

Morphology evaluation of a polymer–fullerene bulk heterojunction ensemble generated by the fullerene derivatization

“…The photovoltaic device parameters are shown on the right hand side. As compared to the original optimization with PCBM, 47,56 all photovoltaic parameters and the device performance are very weak. Since films of similar or even smaller thickness yielded up to 6.6 mA cm À2 short circuit current density, the major part of the generated charge carriers were either not generated or must have recombined before reaching the electrodes.…”