Abstract In recent years, organic solar cells (OSCs) have shown high power efficiencies approaching 20%. However, the fundamental mechanisms of charge separation in these highly efficient devices have been a subject of intensive debates. Here, the charge separation efficiency (CSE) is extensively investigated across a wide range of blend systems with different energetic offsets. The findings unveil the temperature‐dependent nature of charge separation in low‐offset systems, emphasizing its significant contribution to the overall CSE. An intriguing inverse correlation between CSE and charge separation activation energy in relation to the offset is also observed. These results shed new light on the factors underlying the high CSE observed in the state‐of‐the‐art devices.

The Role of Thermally Activated Charge Separation in Organic Solar Cells

Department of Physics Chemistry and Biology (IFM) Linköping University  Linköping 58183 Sweden

Department of Molecular Compound Physics Center for Physical Sciences and Technology  Vilnius LT‐10257 Lithuania

Laboratory of Organic Electronics Department of Science and Technology (ITN) Linköping University  Norrköping SE‐60174 Sweden

Department of Electronic and Information Engineering Research Institute for Smart Energy (RISE) Photonic Research Institute (PRI) Guangdong‐Hong Kong‐Macao Joint Laboratory for Photonic‐Thermal‐Electrical Energy Materials and Devices The Hong Kong Polytechnic University  Hung Hom, Kowloon Hong Kong 999077 China