Regio-regular alternating diketopyrrolopyrrole-based D-A-D-A terpolymers for the enhanced performance of polymer solar cells.

We designed and synthesized regio-regular alternating diketopyrrolopyrrole (DPP)-based D-A-D-A terpolymers (PDPPF2T2DPP-T2, PDPPF2T2DPP-TVT, and PDPPF2T2DPP-DTT) using a primary donor (D) [3,3'-difluoro-2,2'-bithiophene (F2T2)] and a secondary donor (D) [2,2'-bithiophene (T2), ()-1,2-di(thiophen-2-yl)ethene (TVT), or dithieno[3,2-:2',3'-]thiophene (DTT)]. A PDPP2DT-F2T2 D-A polymer was synthesized as well to compare optical, electronic, and photovoltaic properties. The absorption peaks of the terpolymers (PDPPF2T2DPP-T2, PDPPF2T2DPP-TVT, and PDPPF2T2DPP-DTT) were longer ( = 801-810 nm) than the peak of the PDPP2DT-F2T2 polymer ( = 799 nm), which is associated with the high-lying HOMO levels of the terpolymers (-5.

Interesting phase behaviors and ion-conducting properties of dicationic -alkylimidazolium tetrafluoroborate salts.

A series of dicationic imidazolium bis(tetrafluoroborate) salts were newly synthesized, and their phase transition behaviors were correlated with thermal, scattering, optical and conductivity results. The bis-imidazolium salts having side-chain lengths of C-C showed plastic crystal mesophases, while a liquid crystal mesophase was formed in the bis-imidazolium salts with long side-chains (C and C). Soft plastic and liquid crystalline phases were also confirmed by wide-angle X-ray diffraction.