Over the past 30 years, I have pursued research on the precise control of doping levels (DLs) and molecular structure in conjugated organic materials for understanding their molecular properties and applying them to photo‐ and electroactive materials. In this personal account, an overview of studies analyzing the molecular characteristics of conjugated oligomers—including their optical, electrochemical, thermal, and electrical properties—is provided in relation to the main‐chain π ‐conjugated length, the electron‐donating and ‐accepting nature of side chains, and the DLs. Furthermore, the development of dye molecules and polymeric materials based on these oligomers and their applications in energy‐related devices, such as electrochromic smart windows, dye‐sensitized solar cells, organic photovoltaics, and organic thermoelectrics, are described. By integrating molecular design with doping control, these efforts bridge the gap between property design and device‐level functionality, offering valuable guidelines for the future development of high‐performance organic materials.
Ichiro Imae (Wed,) studied this question.