Carbon Electrodes for Perovskite Photovoltaics: Interfacial Properties, Meta-analysis, and Prospects

Abstract

Carbon electrodes have gained significant attention as a cost-effective, sustainable, stable, and scalable replacement for metal electrodes in perovskite solar cells (PSCs). However, traditional carbon-electrode-based PSCs (C-PSCs) lack a hole-selective layer (HSL) due to their incompatibility with the most effective organic HSLs employed in the PSC literature. In turn, the absence of an HSL has been identified as one of the main factors hindering the performance of C-PSCs. Consequently, numerous studies have recognized the pivotal significance of the region between the perovskite absorber and the carbon electrode in C-PSCs, proposing various interfacial engineering strategies to improve the performance of these solar cells. Given the rapid evolution of this field, an up-to-date and comprehensive review of C-PSCs is in order. Key areas of focus of this review include the shift from high-temperature to low-temperature carbon electrodes, strategies to improve energetic alignment at the interface, novel approaches such as hole-selective bilayers, and alternative carbon deposition methods to reduce solvent damage. Additionally, this review presents a comprehensive meta-analysis—the first of its kind in the C-PSC literature—to assess how various interfacial modifications impact critical C-PSC performance metrics, offering valuable insights for future advancements in the field.