Center for Functional Nanomaterials Seminar

The efficient transport and interconversion of energy between photons and matter underpins life on earth, and inspires modern technology. Contrary to natural systems, however, in modern energy conversion systems ranging from solar panels to computers, semiconductors to photocatalysts, energy moves slowly, randomly and often inefficiently towards target conversion sites. My work aims to investigate how energy can be directed in molecules and materials in ways that are efficient and targeted, moving beyond stochastic fluctuation driven energy migration. My comprehensive research in the multidimensional ultrafast electronic spectroscopic of functional materials, natural photosynthetic proteins, and photocatalysts has set important precedents in this direction. In a recent study, we discovered how quantum nuclear vibrations participate during a photoinduced electron transfer reaction like a sequence of ratchets, progressively enhancing electron transfer efficiency and rate (submitted). By studying nuclear coherences, we were able to measure unprecedented dynamics along three distinct reaction coordinates for an intermolecular ET reaction. This electronic-nuclear interplay often manifests in the form of an anomalous dispersion of nuclear coherences coupled to the reaction (JACS, 2019). Our breakthrough work on reactivity of transition metal photocatalysts unraveled how quantum vibrational coupling can lead to selective and targeted bond activation (Chem, 2019). We were able to show that quantum vibrational coupling can acts as a conduit to shuttle energy from light absorbing moiety of the transition metal complex to the active reaction site. We also showed that a directional electron density and energy migration from light absorbing ligands to the functional site opens a controlled photoactivation pathway (JACS 2018). The insights from these and other works strongly indicate that exploiting order/synchronization provided by electronic-nuclear interdependencies can help extracting more energy from solar light conversion, speeding up quantum information transport, enhancing carrier transport, and increasing photocatalytic efficiency.