A new benzodithiophene-based copolymer PTG1 with dithienylbenzothiadiazole-vinylene side chains exhibits excellent film-forming ability, a deep HOMO energy level, and a good miscibility with PC(71)BM. Bulk heterojunction polymer solar cells fabricated from PTG1 and PC(71)BM showed a promising power conversion efficiency over 4.0%.

Three novel copolymers (PT-ID, PT-DTBT, and PT-DTBTID) of benzo­[1,2-b:4,5-b′]­dithiophene and thiophene with different conjugated side groups (1,3-indanedione (ID), 4,7-dithien-5-yl-2,1,3-benzodiathiazole (DTBT), and DTBT-ID) were synthesized and developed for polymer solar cell applications. The effects of the different conjugated side groups on the thermal, photophysical, electrochemical and photovoltaic properties of these copolymers were investigated. As the length of the conjugated side groups increased, the absorption of the UV–vis region in solution was red-shifted. By changing the different side groups, the energy levels and band gaps of the resulted copolymers were effectively tuned. The three copolymers exhibit deep HOMO energy level and relatively high open-circuit voltage (V oc ). Bulk heterojunction solar cells with these copolymers as electron donors and (6,6)-phenyl-C61-butyric acid methyl ester (PC61BM) as an electron acceptor exhibit power conversion efficiencies of 2.48%, 4.18% and 1.16% for PT-ID, PT-DTBT, and PT-DTBTID, respectively.

No abstract

A series of novel low band gap polymers containing conjugated side chains with 4,7‐dithien‐5‐yl‐2,1,3‐benzodiathiazole and different electron‐withdrawing end groups of aldehyde (PT‐DTBTCHO), 2‐ethylhexyl cyanoacetate (PT‐DTBTCN), 1,3‐diethyl‐2‐thiobarbituric acid (PT‐DTBTDT), and electron‐donating end group of 2‐methylthiophene (PT‐DTBTMT) have been designed and synthesized. All polymers exhibit good solubility in common organic solvents, film‐forming ability, and thermal stability. These conjugated polymers show the broad ultraviolet‐visible absorption and the narrow optical band gaps in the range of 1.65–1.90 eV. Through changing the end group of conjugated side chains, the photophysical properties and energy levels of the polymers were tuned effectively. Bulk heterojunction solar cells based on the blend of these polymers and (6,6)‐phenyl‐C61‐butyric acid methyl ester (PC61BM) reached the best power conversion efficiency (PCE) of 2.72%. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012

No abstract