Research progress on solution-processed transparent electrodes for organic solar cells

Solution-processed transparent electrodes represent a promising route toward low-cost, flexible, and scalable organic photovoltaics. This review surveys recent advances in such electrodes—including silver nanowires, conductive polymers, carbon-based materials and composite materials—for use as both bottom and top contacts in organic solar cells (OSCs). We discuss material designs and interfacial engineering strategies that improve electrical conductivity, optical transparency, and compatibility with underlying organic layers. Notably, the performance of solution-processed electrodes now rivals that of conventional vacuum-deposited ones, enabling fully solution-fabricated OSCs with competitively high power conversion efficiencies. While key challenges persist, such as balancing sheet resistance with transmittance, ensuring long-term operational stability, and achieving uniformity over large areas. Moving forward, further innovations in materials, interface control, and scalable deposition techniques will be crucial to enable the widespread adoption of solution-processed electrodes in flexible, semi-transparent, and building-integrated photovoltaics.