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The intra and intermolecular interactions (J‐ and H‐type aggregation) in the conjugated polymer films are found to readily facilitate the electron and hole transport, respectively. However, how those different aggregation types influence the photocurrent generation at the heterojunction is still mysterious, especially for the newly developed semicrystalline conjugated polymers. Here, the prototypical copolymer PM6 is used to tune the relative content of aggregation types with various halogen‐free processing solvents. Various measurements reveal that the toluene‐processed PM6 film exhibits the increased H‐aggregates and crystallinity in the π–π stacking direction compared to its o‐xylene‐ and trimethylbenzene (TMB)‐processed counterparts. This is partly resulted from the weak steric effect and good solubility in the PM6 solution prepared with toluene, which strengthens the intermolecular interaction of adjacent polymer segments. After analyzing the photovoltaic properties of PM6/Y6 bilayer devices, the faster charge carrier transport, smaller charge recombination, lower energy losses, and interfacial energetic disorder can be observed in the toluene‐processed device, leading to the synergistically improved short‐circuit current density (JSC) and open‐circuit voltage (VOC). These findings indicate the control of the molecular packing structure in terms of aggregation types is a powerful strategy to promote the photocurrent generation process at the conjugated polymer‐based heterojunction. [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]