Thick-Film All-Polymer Organic Solar Cells: Non-Halogen Solvent Processing for Efficient and Stable Photovoltaics

Abstract

The industrial application of high-efficiency organic solar cells (OSCs) faces dual challenges: reliance on thin active layers (80–120 nm) and inadequate stability under prolonged illumination. Here, we overcome these limitations by fabricating thick-film all-polymer OSCs (100–300 nm) via a non-halogen solvent (toluene)-assisted sequential processing strategy (PM6/PJ1-γ system). The 300 nm-thick device achieved a power conversion efficiency (PCE) of 16.01% alongside remarkable operational stability (T80 = 465 hours) under continuous light conditions, exhibiting a 220% stability improvement over the 100 nm device (PCE = 18.21%, T80 = 145 hours). In situ UV-vis monitoring revealed that slower film formation kinetics in thicker layers promoted structurally homogeneous bulk heterojunctions, corroborated by atomic force microscopy showing minimal surface roughness variation. Impedance spectroscopy and transient photoelectric characterization elucidated the thickness-dependent balance between charge transport and recombination: while thin films exhibited superior carrier mobility, thick films synergized enhanced light harvesting with robust morphology to optimize efficiency-stability trade-offs. Our work demonstrates that all-polymer OSCs with thick active layers can simultaneously achieve high efficiency and long-term stability, positioning them as strong candidates for large-scale industrial applications in organic photovoltaic.