Dear colleagues,

It is our great pleasure to announce the 15th International Conference on Optical Probes of Organic and Hybrid Semiconductors (OP2025) held in Fukuoka, Japan in September 2025. Optical Probes is a single session conference that discusses a variety of topics in the field of photophysics of organic and hybrid materials including optical spectroscopy and excited state phenomena in organic and hybrid semiconductors, π-conjugated polymers, molecules and related optoelectronic devices, perovskite materials and related optoelectronic devices, strong light-matter interaction, quantum confined nanostructures, and optical materials for biological application. The primary goal of OP2025 is to present state-of-the-art research, recent achievements and global trends in our understanding of excited state phenomena and photophysical processes, the development of novel spectroscopic techniques, and their applications, mostly to optoelectronic devices, photonics and biology. Special emphasis is placed on generality of the phenomena, rather than the specifics of the system or optical measurements.