Probing Coherent Aggregate Exciton Energy Transfer in Organic Dopant Systems

Le résumé fourni par la source

Probing quantum coherence in exciton energy transfer processes is critical for understanding and designing advanced organic optoelectronic devices. Current methods, such as transient absorption spectroscopy, are highly complex and require intricate experimental setups, limiting their accessibility for routine examinations. Furthermore, direct experimental comparison of energy transfer efficiency between aggregate versus monomer exciton to acceptor is also lacking. Here, we demonstrate a simple spectroscopic approach that shows differentiation for different exciton populations in engineered organic dopant systems. By using a pyrene derivative as the dopant within the crystal of a naphthalene derivative, the type of excitonic energy transfer from naphthalene to pyrene is strongly selective. Specifically, the coherent aggregate exciton population is almost entirely depleted despite a better energy match between the pyrene absorption and the naphthalene monomer emission, which largely persists in the presence of pyrene dopants. By chemically modifying the naphthalene energy donor, the populations of aggregate and monomer excitons can be systematically tuned, which directly correlates with the sensitivity of the pyrene photoluminescence in doped naphthalene crystals at a fixed concentration. These findings have important implications for understanding exciton dynamics in organic light-emitting devices.

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