Fine-Tuned Active Layer Morphology for Bulk Heterojunction Organic Solar Cells with Indene-C60 Bisadduct as a Third Component

Active layer morphology is of vital importance for the photovoltaic performance of organic solar cells (OSCs). As fullerene derivatives and nonfullerene acceptors are highly complementary in many aspects, fullerene derivatives as a third component in nonfullerene OSCs could tune the blend morphology and improve the power conversion efficiency (PCE). Relative to PCBM, the indene-C60 bisadduct (IC₆₀BA) as the third component in nonfullerene binary OSCs has not been extensively studied. Here, the fullerene derivative IC₆₀BA is introduced into the PTZ1:IDIC blend system to finely tune the active layer morphology. Although the addition of IC₆₀BA reduced the film absorption in the visible region and weakened the crystallinity, the more symmetric charge transport property, smaller domain size, and higher domain purity led to improved photovoltaic performance. This study indicates that IC₆₀BA is a promising candidate to finely tune the morphology for achieving highly efficient OSCs.