Optimized active layer morphology toward efficient and polymer batch insensitive organic solar cells
Morphology control in laboratory and industry setting remains as a major challenge for organic solar cells (OSCs) due to the difference in film drying kinetics between spin coating and the printing process. A two step sequential deposition method is developed to control the active layer morphology. A conjugated polymer that self assembles into a well defined fibril structure is used as the first layer, and then a non fullerene acceptor is introduced into the fibril mesh as the second layer to form an optimal morphology. A benefit of the combined fibril network morphology and non fullerene acceptor properties was that a high efficiency of 16.5% (certified as 16.1% was achieved. The preformed fibril network layer and the sequentially deposited non fullerene acceptor form a robust morphology that is insensitive to the polymer batches, solving a notorious issue in OSCs. Such progress demonstrates that the utilization of polymer fibril networks in a sequential deposition process is a promising approach towards the fabrication of high efficiency OSCs. Reliably controlling the morphology in organic solar cells is desired for up scaling. Here Weng et al. combine the advantages of the fibril network donor and the state of the art Y6 acceptor in a two step approach to deliver a high efficiency of 16% without batch to batch variation.
Nature Communications