Present microelectronic photoimaging applications employ onium salts for deep UV (I-line, 365 nm) photolithography. Since most onium salts do not absorb at this wavelength, photosensitizers are commonly employed. Polynuclear aromatic hydrocarbons are the most efficient known examples of electron-transfer photosensitizers for onium salts. However, they have serious drawbacks that limit their use, such as they are expensive, toxis, and poorly soluable in most reactive monomers and polymer systems. This invention is directed to using an inexpensive, natural, non-toxic compound as a photosensitizer to enable the UV cure of epoxy resins with visible light. The compound can be used in such applications as coatings, dental composites, and sterrolithography.