The morphology of the active layer of a bulk heterojunction (BHJ) solar cell, made of a blend of an electron-donating polymer and an electron-accepting fullerene derivative, is known to play a determining role in device performance. Interestingly, even a minor change in the chemical structure of the polymer backbone has been shown experimentally to change substantially the blend morphology. Here, taking representative systems based on benzothiadiazole-quaterthiophene polymers and PC<sub>71</sub>BM, we discuss the results of molecular dynamics simulations and long-range corrected density functional theory calculations. We elucidate the molecular-scale effects that even minor structural changes to the polymer backbone can have on the ″local″ morphology; we focus on the extent of polymer-fullerene mixing, on their packing, and on the characteristics of the fullerene-fullerene connecting network in the mixed regions, aspects that are difficult to access experimentally.<br/><br/>

Polymer-acceptor bulk heterojunction solar cells: Establishing relationships among polymer chemical structure, polymer packing, and polymer-acceptor mixing

255th National Meeting (2018)

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