Doping for organic solar cells

Abstract

Crucial for mitigating energy scarcity and environmental degradation, the development of novel energy technologies positions organic solar cells (OSCs) as a leading photovoltaic candidate due to their intrinsic advantages of flexibility, light weight, and solution processability. Concurrent advancements in materials and processing have enabled certified power conversion efficiencies (PCEs) to surpass the 20% threshold. However, inherent material limitations, specifically low dielectric constant, sluggish carrier mobility, and a large exciton binding energy, severely impede further performance enhancement. Doping techniques provide an effective strategy for precisely tailoring the electrical characteristics of organic semiconductors, thereby circumventing these limitations and serving as a crucial driver for progress across the broader field of organic electronics. This review systematically examines recent advancements (over the last five years) in applying doping techniques to OSCs. We primarily focus on active layer doping methodologies, including co-doping, sequential doping, layer-by-layer doping, and solid additive-assisted doping, while also discussing the optimization of interfacial engineering for charge transport layers. Finally, we outline the three critical challenges facing the integration of doping technology into future development of OSCs, providing potential directions for future research in the field.