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ABSTRACT We have investigated the effect of solvent-polymer interaction on the morphology, crystallinity, and device performance of poly-(3-hexylthiophene) (P3HT) and poly{2,7-(9,9-didodecyl-fluorene)-alt-5,5-[4′,7′- bis(2-thienyl)-2′,1′,3′-benzothia-diaole]} (PF12TBT) blend system. 3-Hexylthiophene (3-HT), which had the similar structural units with both donor and acceptor materials, was chosen as the solvent additive to be added into the main solvent chlorobenzene (CB), to adjust the solvent-polymer interaction. With the 3-HT percentage increasing from 5 to 30% in CB solution, the solvent-polymer interaction between polymer and solvent molecules decreased slightly according to the calculated solubility parameters ( δ) and interaction parameters ( χ12). As a result, nanoscale phase-separated and interconnected morphology with decreased domain size of both donor and acceptor was formed. Meanwhile, the order of P3HT molecule was enhanced which resulted from the extended film drying time and increased molecular planarity after incorporation of 3-HT. The power conversion efficiency (PCE) had a gradual improvement to 1.08% as the 3-HT percentage reached 10%, which can be attributed to the enhanced short-circuit current ( Jsc) and fill factor (FF). However, when the 3-HT percentage exceeded 20%, the decreased Jsc and FF ultimately decreased the PCE. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2015, 53, 288-296 [ABSTRACT FROM AUTHOR]

ABSTRACT The selection of sensitizer and its existence in the blend films are important to the performance of all-polymer ternary solar cells. Herein, all-polymer ternary solar cell devices, which used poly[4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)benzo[1,2-b:4,5-b′] dithiophene-alt-3-fluorothieno[3,4-b]thiophene-2-carboxy-late] (PTB7-Th) as donor, poly[[ N, N-bis(2-octyldodecyl)-napthalene-1,4,5,8-bis(dicarboximide)−2,6-diyl]-alt-5, 5′-(2,2′-bithiophene)] (N2200) as acceptor and poly[ N−900-hepta-decanyl-2,7-carbazole-alt-5,5-(40,70-di-2-thienyl-20,10,30-benzothiadiazole) (PCDTBT) as sensitizer, are successfully demonstrated. The intermolecular interaction between donor PTB7-Th and sensitizer PCDTBT may lead to aggregation of PTB7-Th which decreases domain sizes and enlarges D/A effective interface area. In addition, the PCDTBT molecules also extend light absorption and cascaded energy levels of the ternary blend system. As a result, with 15% PCDTBT we get a power conversion efficiency of 5.11%, almost 20% higher than control device due to more favored exciton dissociation and higher charge transport efficiency. This study reveals a promising way to achieve high efficiency all-polymer solar cells using a low-band gap polymer PCDTBT. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016, 54, 1811-1819 [ABSTRACT FROM AUTHOR]