The Polymer Society of Korea

Abstract

Organic photodiodes (OPDs) are attractive for next-generation optoelectronics because of their lightweight nature, mechanical flexibility, and low-cost solution-based fabrication. Short-wave infrared detection is important for sensing, imaging, and transparent electronic systems, yet development is constrained by a key trade-off: extending absorption to longer wavelengths often reduces efficient charge separation.
Red-shifted absorption is achieved through strong intramolecular charge transfer (ICT), which broadens the spectral response. However, excessive ICT promotes electronic localization, limiting exciton dissociation and charge mobility, leading to low responsivity and high noise in ICT OPDs.
To address this, two approaches are proposed: tuning the degree of ICT to balance charge transfer and electronic delocalization, and applying external modulation such as chemical or electrochemical doping to introduce additional electronic states and improve charge transport.