Rational Third Component Choices Drive Enhanced Morphology and Efficiency in Ternary Blend Organic Solar Cells

The impetus to add a third component in ternary blend organic solar cells (TBSCs) maximizes the light-harvesting capability of the active layer. Beyond this, the third component can perform other useful functions, such as enhancing the morphology and charge transport, and assisting in resonance energy transfer. Currently, there are no established guidelines for selecting the third component in TBSCs to optimize the organic solar cell (OSC) performance. By varying the chromophore chain length of perylene diimide (PDI) molecules, we revealed its influence on the morphology of the thin film and the efficiency of PM6:Y6 OSCs. Detailed optical and electrical characterization and morphological studies revealed that molecular size and PDIs’ chromophore chain length are pivotal to improving the performance of OSCs. The PDI monomer acts as an additive to improve the morphology and light-harvesting capability of TBSCs. This study presents several significant findings, including the dual role of the third component, the influence of the chromophore chain length on morphology, and the dynamics of excited states.