摘要： Understanding the intermolecular interactions in the organic dye mixtures could be critical for the design of high-performance optoelectronic devices. In the present study, we investigate the intermolecular interactions in dye systems combining two kinds of organic dyes, using the coumarin 343 (C343) as an example. The study employs the first principles calculations and the spectroscopic/electrochemical experiments to explore the intermolecular interactions (either synergistic or antagonistic) and their effects on the electronic and optical properties of the hybrid dye systems. The interactions between the coumarin dye and four other dyes, either as free dyes or as self-assembled monolayers that are adsorbed onto semiconductor substrate, are analyzed via the UV–Vis absorption, the emission and the photocurrent measurements. The four dyes include 4-(4-diethylaminophenylazo)pyridine, chlorophosphonazo III, methyl red, and catechol, which have been applied to optoelectronic devices. In particular, the interaction between C343 and 4-(4-diethylaminophenylazo)pyridine is found to be synergistic for the photocurrent generation using the aqueous electrolyte, which is not observed in other systems. The study suggests importance of the intermolecular interactions in the hybrid-dye systems, and might provide fundamental insights on the intermolecular interactions that could be leveraged to design optoelectronic devices.