Environmental aging mechanisms in organic semiconductors

Abstract

Organic semiconductors have attracted significant attention for electronic and optoelectronic systems due to their low-temperature processability, mechanical flexibility, and structural tunability. However, their practical implementation is limited by environmental aging induced by exposure to oxygen and moisture. Different from inorganic semiconductors, organic semiconductors possess relatively open molecular packing and intrinsic free volume, which facilitate the diffusion and activation of environmental species and trigger complex degradation processes. This review presents a comprehensive and mechanism-oriented overview of environmental aging mechanisms in organic semiconductors, with focus on oxygen- and water-induced chemical, structural, and electronic degradation. We discuss how photoexcited states and charge carriers activate molecular oxygen to generate reactive oxygen species, initiating selective chemical reactions at vulnerable molecular motifs. The resulting molecular modifications are correlated with morphological evolution, interfacial degradation, and mechanical failure, leading decay of device. Representative characterization approaches, including SEM, AFM, KPFM, UV-Vis spectroscopy, photoluminescence, XPS, and FT-IR, are summarized to illustrate how aging processes can be observed and quantified. By integrating chemical, structural, electronic, and spectroscopic perspectives, this review establishes a unified framework for understanding environmental aging in organic semiconductors. Also, it provides insights for improving long-term stability in organic semiconductor devices.