[6,6]‐phenyl‐C‐61‐butyric acid methyl ester (PCBM) and poly(3‐hexylthiophene) (P3HT) are the most widely used acceptor and donor materials, respectively, in polymer solar cells (PSCs). However, the low LUMO (lowest unoccupied molecular orbital) energy level of PCBM limits the open circuit voltage (Voc) of the PSCs based on P3HT. Herein a simple, low‐cost and effective approach of modifying PCBM and improving its absorption is reported which can be extended to all fullerene derivatives with an ester structure. In particular, PCBM is hydrolyzed to carboxylic acid and then converted to the corresponding carbonyl chloride. The latter is condensed with 4‐nitro‐4’‐hydroxy‐α‐cyanostilbene to afford the modified fullerene F. It is more soluble than PCBM in common organic solvents due to the increase of the organic moiety. Both solutions and thin films of F show stronger absorption than PCBM in the range of 250–900 nm. The electrochemical properties and electronic energy levels of F and PCBM are measured by cyclic voltammetry. The LUMO energy level of F is 0.25 eV higher than that of PCBM. The PSCs based on P3HT with F as an acceptor shows a higher Voc of 0.86 V and a short circuit current (Jsc) of 8.5 mA cm−2, resulting in a power conversion efficiency (PCE) of 4.23%, while the PSC based on P3HT:PCBM shows a PCE of about 2.93% under the same conditions. The results indicate that the modified PCBM, i.e., F, is an excellent acceptor for PSC based on bulk heterojunction active layers. A maximum overall PCE of 5.25% is achieved with the PSC based on the P3HT:F blend deposited from a mixture of solvents (chloroform/acetone) and subsequent thermal annealing at 120 °C.

Diamino-5′-phenyl-or 4-alkoxyphenyl-m-terphenyl and 4,4′′-dicarboxy-5′-phenyl-mterphenyl were synthesized through pyrylium salts and used for the preparation of rigid-rod polyamides and polyimides. The polymers were characterized by inherent viscosity, elemental analysis, FT-IR, UVvis, 1 H NMR, 13 C NMR, X-ray, DSC, TMA, TGA, isothermal gravimetric analysis, and moisture absorption. It was shown that the presence of the 4-alkoxyphenyl pendent groups enhanced remarkably the solubility of polymers as well as reduced the Tg's and thermal stability. In addition, the polyamide bearing 4-(dodecyloxy)phenyl side groups displayed softening.

Four new soluble poly(p-phenylenevinylene) (PPV) derivatives containing one or two quinoxaline moieties per repeat unit, either in the main chain or as pendants to the main chain, were synthesized, characterized, and explored as emissive and electron transport materials in polymer lightemitting diodes (LEDs). Polymers containing one quinoxaline moiety per repeat unit (QXPV1 and QXPV3) showed low melting transitions (<100 °C), whereas those with two quinoxaline moieties per repeat unit (QXPV2 and QXPV4) had relatively high glass transition temperatures (>140 °C). The polymers emit blue to green light (404-536 nm) in dilute solution and blue-green to yellow light (470-563 nm) in the solid state. The photoluminescence emission was well-described by single-exponential decay with lifetimes ranging from 200 ps to 2.2 ns in both dilute solution and thin film, indicating lack of intermolecular emissive species in the solid state. PPV derivatives with quinoxaline moieties in the main chain (QXPV1 and QXPV2) showed facile reversible electrochemical reductions with electron affinities of 2.63-2.75 eV. As emissive materials in LEDs, greenish-yellow electroluminescence with a brightness of up to 450 cd/m 2 was obtained from single-layer diodes of QXPV1 with aluminum cathode in air.

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4,3‘‘-Diamino-2‘,6‘-diphenyl- or di(4-biphenylyl)-p-terphenyl (3a or 3b) and 4-amino-4‘‘-carboxy-2‘,6‘-diphenyl-p-terphenyl (6) were synthesized through pyrylium salts and used for the preparation of rigid-rod polyamides and polyimides. The polymers were characterized by inherent viscosity, elemental analysis, FT-IR, 1H-NMR, 13C-NMR, UV−vis, X-ray, differential scanning calorimetry (DSC), thermomechanical analysis (TMA), thermal gravimetric analysis (TGA) isothermal gravimetric analysis, and moisture absorption. They were amorphous. All polyamides as well as the polyimide derived from 3b and benzophenonetetracarboxylic dianhydride dissolved in polar aprotic solvents and H2SO4 98%. Polyamide prepared from 6 showed blue fluorescence in dimethylformamide solution. The T gs of polyamides ranged from 235 to 285 °C. The polymers possessed excellent thermooxidative stability with no weight loss up to 379−417 °C in air.

The reaction of 4,4‘-(1,4-phenylene)bis(2,6-diphenylpyrylium tetrafluoroborate) with nitromethane afforded 4,4‘‘-dinitro-3,5,3‘‘,5‘‘-tetraphenyl-p-terphenyl, which was catalytically hydrogenated to the corresponding diamine. The latter was used as starting material for the preparation of new rigid-rod polyamide, polyimides, and polyazomethine bearing phenyl pendent groups as well as the respective model compounds. Characterization of polymers was accomplished by inherent viscosity measurements, elemental analysis, 1H-NMR, 13C-NMR, X-ray, DTA, TMA, TGA, and isothermal gravimetric analysis. The polymers were amorphous and soluble in polar aprotic solvents. Polyamide showed an outstanding solubility, being soluble even in o-dichlorobenzene and chloroform. Polyamide displayed T g and softening temperature at 135 and 155 °C, respectively, whereas other polymers showed only T g above 265 °C. The polymers were stable up to 397−441 °C in N2 and 344−363 °C in air and afforded anaerobic char yields of 68−77% at 800 °C. In addition, the thermal stability of polyazomethine was investigated as a function of the curing time.

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