Hole mobility of 3.56 cm2V−1s−1accomplished using more extended dithienothiophene with furan flanked diketopyrrolopyrrole polymer

A highly extended dithienothiophene comonomer building block was used in combination with highly fused aromatic furan substituted diketopyrrolopyrrole for the synthesis of novel donor–acceptor alternating copolymer PDPPF-DTT. Upon testing PDPPF-DTT as a channel semiconductor in top contact bottom gate organic field effect transistors (OFETs), it was found to exhibit p-channel behaviour. The highest hole mobility of 3.56 cm2 V−1 s−1 was reported for PDPPF-DTT. To our knowledge, this is the highest mobility reported so far for the furan flanked diketopyrrolopyrrole class of copolymers using conventional device geometry with straightforward processing.

An organic sensitizer with a fused dithienothiophene unit for efficient and stable dye-sensitized solar cells

We report a high molar extinction coefficient organic sensitizer for high efficiency dye-sensitized solar cells. In combination with a solvent-free ionic liquid electrolyte, we have demonstrated a similar to 7% cell showing an excellent stability measured under the thermal and light soaking dual stress. This is expected to have an important practical consequence on the production of flexible, low-cost, and lightweight DSC based on plastic matrix.

Design and modification of three-component randomly incorporated copolymers for high performance organic photovoltaic applications

In this study we report the molecular design, synthesis, characterization, and photovoltaic properties of a series of diketopyrrolopyrrole (DPP) and dithienothiophene (DTT) based donor-acceptor random copolymers. The six random copolymers are obtained via Stille coupling polymerization using various concentration ratios of donor to acceptor in the conjugated backbone. Bis(trimethylstannyl)thiophene was used as the bridge block to link randomly with the two comonomers 5-(bromothien-2-yl)-2,5-dialkylpyrrolo[3,4-c]pyrrole-1, 4-dione and 2,6-dibromo-3,5-dipentadecyl-dithieno[3,2-b;2′,3′-d] thiophene. The optical properties of these copolymers clearly reveal a change in the absorption band through optimization of the donor-acceptor ratio in the backbone. Additionally, the solution processability of the copolymers is modified through the attachment of different bulky alkyl chains to the lactam N-atoms of the DPP moiety. Applications of the polymers as light-harvesting and electron-donating materials in solar cells, in conjunction with PCBM as acceptor, show power conversion efficiencies (PCEs) of up to 5.02%.

Synthesis, characterization, photoluminescent and electroluminescent properties of new conjugated 2,2 '-(arylenedivinylene)bis-8-substituted quinolines

A series of new PPV oligomers containing 8-substituted quinoline, 2,2'-(arylenedivinylene) bis-8-quinoline derivatives, were designed and synthesized via a Knoevenagel condensation reaction of quinaldine, 8-hydroxy-or 8-methoxy-quinaldine with aromatic dialdehydes. These PPV oligomers were characterized by H-1 and C-13-NMR, X-ray diffraction, elemental analysis, UV-visible and fluorescence spectroscopies. The X-ray diffraction investigation showed that there are intermolecular pi...pi interactions in the solid state in 1 and 3. The optical and photoluminescent properties study demonstrated that the emission color of the resulting materials varies from blue to yellow and is dependent on the substituents (pi-donor and pi-acceptor groups) on both sides of the conjugated molecules and the aromatic core in the middle of the conjugated backbones. The electroluminescent devices using compounds 1-4 as the emitters and electron-transporting layers were fabricated with the structure ITO/NPB/emitter/LiF/Al. The best device performance with the maximum brightness of 5530 cd m(-2) and the luminous efficiency of 2.4 cd A(-1) is achieved by using compound 4, with intramolecular charge transfer character, as the emitter; these values represent a more than 5-fold improvement in brightness and efficiency compared to compound 3 without methoxy groups on the phenyl rings.