Miscibility-Driven Optimization of Nanostructures in Ternary Organic Solar Cells Using Non-fullerene Acceptors

Non-fullerene acceptors (NFAs) with vibrant superiority over fullerene derivatives have proved advantageous as a guest component in a ternary blend signifying improved photon harvesting. However, heterogeneity of NFA-based ternary blend morphology is very complex, and the optimization requires simultaneous considerations of molecular miscibility and electronic properties. We discuss the role of guest NFA for an eased optimization of ternary blend photoactive layer in four different ways. Our four-model prospect of component selection is driven by the well-matched intrinsic miscibility, electronic, and optical characteristics of organic materials. We analyze each model, modulating photoactive layer morphology toward efficient transfer, transport, and collection of charges along with their balanced dissociation and drifting. We believe a model-based selection of NFA and its organization as a guest in a complex ternary blend will serve as a guide for researchers to optimize thin film nanostructures, a route toward efficient larger-area ternary devices. Organic solar cells (OSCs) have proved to be one of the most progressive and inexpensive solutions of sustainable energy. Ternary strategy can exploit the complementary absorption of three components to cover the maximum solar spectrum. Non-fullerene acceptors (NFAs), offering absorption from the visible to near infrared (NIR) regions, is a vibrant prospect to be exploited further in ternary OSCs. However, complex ternary blend morphology constituting multifarious phase separation yields low contrast for its characterization. We propose four miscibility-driven models for a predictable organization of guest NFA in complex nanostructure phases and interfaces of ternary blend toward an eased optimization of the photoactive layer. For an efficient ternary blend, careful selection of organic materials can provide electronic properties such as enhanced charge transfer and transport, balanced transfer, and transport for proficient charge collection and maximized quantum yield from harvested solar energy. We have presented four models for efficient charge transfer using miscible guest NFAs and host donors, efficient charge transport using non-miscible guest NFAs and host donors, efficient quantum yield of harvested solar energy using low miscibility between all three components, and balanced generation and transport of charges for their proficient collection using two miscible NFAs, resulting in improved performance of optimized NFA-based ternary OSCs.