Efficient low-band-gap polymers are one key component for constructing tandem solar cells with other higher-band-gap materials to harvest wide absorption of the solar spectrum. The N-acyldithieno[3,2-b:2′,3′-d]pyrrole (DTP) building block is used for making low-band-gap polymers. It is attractive because of its strong donating ability and relatively low highest-occupied-molecular-orbital level in comparison with the N-alkyl DTP building block. However, additional solubilizing groups on the accepting units are needed for soluble donor–acceptor polymers based on the N-alkanoyl DTP building block. Combining N-benzoyl DTP with a 4,7-dithieno-2,1,3-benzothiadiazole building block, a polymer with a low band gap of 1.44 eV, delivers a high short-circuit current of 17.1 mA/cm2 and a power conversion efficiency of 3.95%, which are the highest for the devices with DTP-containing materials. Herein, an alcohol-soluble diamine-modified fullerene cathode interfacial layer improved the device efficiency significantly more than the mono-amine analogue.Keywords: amine-modified fullerene; interfacial materials; low-band-gap polymers; N-acyldithienopyrrole; polymer solar cells;

Long aromatic polyamide chains are prepared from the corresponding monomers. The resultant polymer adopts a hollow helical conformation that is stabilized by intramolecular H-bonding interaction between side chains.

The presence of covalent tethers significantly enhanced the stability of structures consisting of helically arranged benzenetricarboxamide units that otherwise undergo very weak hydrogen-bonding interaction. The resultant molecular structures were probed by computational study, which predicted folded conformations consisting of helically arranged discs. Experimental studies confirmed the H-bonding interaction between the disk units, the monomeric nature of the corresponding molecules in solution, and the helical conformations of such molecules.

Long aromatic polyamide chains are prepared from the corresponding monomers. The resultant polymer adopts a hollow helical conformation that is stabilized by intramolecular H-bonding interaction between side chains.