All-SAM interfacial architecture for perovskite solar cells without charge transport materials.

State-of-the-art perovskite solar cells (PSCs) employ a multilayer device structure, incorporating a combination of charge transport layers and interfacial modifications to achieve efficient charge extraction. However, simplifying the device structure is highly desirable for cost-effective mass production. One approach is to integrate multiple functions into a single monolayer, replacing the multilayer structure. To explore this concept, we propose a device architecture where a combination of p-type and n-type self-assembled monolayers (SAMs) is employed to construct the hole-extraction and electron-extraction interfaces in a PSC without charge transport layers. The resulting device successfully establishes charge selectivity, achieving a substantial photovoltaic output and promising stability. This fully SAM-based interfacial architecture presents a promising strategy for making efficient solar cells with a minimum demand of materials and processes. The proposed device architecture can be applied to other types of thin-film devices and introduces a new approach of designing interfaces at the molecular level.