Fully evaporated interfacial layers for high-performance and batch-to-batch reproducible organic solar modules†

Abstract

Significant advancements in research have been made in recent years, with single-junction organic solar cells achieving efficiencies exceeding 20%. However, scaling up laboratory prototypes to large-area commercial modules remains challenging due to the absence of high-quality thin-film deposition techniques, particularly for ultra-thin interfacial layers. Herein, we demonstrate a fully vacuum-processed approach utilizing InCl₃ as a hole-contact and C₆₀/BCP as an electron-contact interlayer, respectively, which act as dense and uniform charge transporting layers, while also ensuring consistent batch-to-batch reproducibility of module performance. In addition, such an ultra-thin InCl₃ layer significantly reduces the surface free energy of ITO substrates, thereby inhibiting the coffee ring effect during the active layer deposition and obtaining a more homogeneous film in a large-scale size. As a result, we measured a power conversion efficiency of 16.5% (certified efficiency: 15.8%) under 1-sun illumination for the best-performing organic solar modules (aperture area = 15.6 cm²) with a geometric fill factor of 95.5%, making them highly competitive amongst recently reported modules of similar size. Most importantly, our vacuum-processed interlayers exhibit excellent reproducibility and scale-up ability, paving the way to accelerate the industrialization of organic photovoltaic technology.