1. Ultrafast Photochemistry
We investigate photoinduced ultrafast dynamics in small molecules and molecular aggregates, where light triggers rapid electronic and structural changes. Using advanced ultrafast spectroscopy, we track real-time processes such as energy relaxation, charge transfer, bond rearrangement, and exciton migration, revealing how molecular interactions shape photochemical pathways in condensed environments. These insights advance understanding of light-driven reactions in photophysics, photobiology, and functional materials.
2. Solar energy conversion
We aim to understand ultrafast molecular and charge carrier processes govern solar energy conversion in emerging photovoltaic materials. Efficient solar energy harvesting relies on a cascade of fundamental steps, including exciton formation, charge generation, carrier diffusion, and recombination, spanning timescales from femtoseconds to microseconds. This provides direct insight into carrier transport, diffusion lengths, and the recombination pathways that limit device performance. A key focus is also on hot-carrier relaxation, probing electron-phonon coupling and polaron formation to reveal how vibrational motions influence charge transport and thermalization, with the potential to exceed conventional photovoltaic efficiency limits.
3. Organic Light Emitters
Our second research theme focuses on advancing organic light-emitting materials for next-generation OLED display and lighting technologies. Organic semiconductors are attractive due to their flexibility, low-cost fabrication, and compatibility with lightweight devices. A key challenge in OLEDs is that many excited states form non-emissive triplets, limiting efficiency. Metal-free emitters based on thermally activated delayed fluorescence (TADF) offer a promising route by converting these triplet states into light-emitting singlets. Using ultrafast spectroscopy, we investigate the excited-state and vibrational dynamics that control this triplet harvesting process. These insights will support the rational design of highly efficient, sustainable OLED emitter materials with reduced energy loss.
4. Coherent Multidimensional Spectroscopy
We develop and apply state-of-the-art coherent multidimensional spectroscopy techniques-including broadband transient absorption, time-resolved coherent Raman spectroscopy, and multidimensional electronic spectroscopies-to directly map excited-state pathways in real time. Traditional time-resolved spectroscopies often provide only population decay dynamics and can miss the underlying couplings between electronic states and nuclear motions that shape reaction pathways. In contrast, coherent multidimensional methods capture correlated electronic–vibrational interactions, revealing how excitons, charges, and molecular vibrations evolve together after photoexcitation. These tools allow us to probe inter-exciton couplings, electron-vibration interactions, and coherent energy flow with femtosecond resolution, offering a deeper mechanistic understanding of light-driven processes in complex materials.
