Efficient organic solar cells with a printed p–i–n stack enabled by an azeotrope-processed self-assembled monolayer

Abstract

Self-assembled monolayers (SAMs) are key in enhancing the charge extraction interface of organic solar cells (OSCs), recently hitting a 20% power conversion efficiency (PCE). However, it is very challenging to achieve a uniform coating of ultra-thin amphiphilic SAMs on rough ITO substrates, especially for large-area solution processing. Here, we introduce a novel method employing azeotrope ink for scalable printing of SAM on an ITO surface. The unique solvent combination with different polarities in the azeotrope not only stabilizes the SAM molecules but also ensures controllable solvent evaporation rates. This facilitates the formation of a high-quality SAM to support the subsequent deposition of fully printed p–i–n architecture devices, with the SAM serving as the hole-selective layer. The optimized devices achieved impressive power conversion efficiencies of 18.89% for 0.04 cm² devices and 17.76% for 1 cm² devices, underlining the potential of using azeotrope-assisted SAM printing as a scalable method for fabricating efficient and durable OSCs.