Spatiotemporal thermal transport measurement and imaging
We develop and employ a time-resolved optical technique called vibrational-pump visible-probe (VPVP) spectroscopy. In VPVP, a femtosecond mid-infrared (MIR) optical pump pulse directly excites vibrations of a material, after which the time-dependent optical transmittance across the visible range is probed in the ns to ms time window. This versatile and transducer-free VPVP method, which we run both in spectroscopic and imaging configurations, is used for studying thermal transport properties of organic, polymeric, and hybrid organic-inorganic semiconductors, as well as two-dimensional heterostructures. We interrogate both solid-solid and solid-liquid interfaces.
Relevant publications: J. Am. Chem. Soc. 2024, 146, 2187-2195; J. Phys. Chem. C 2023, 127, 3523-3531; Rev. Sci. Instrum. 2022, 93, 053003
Fundamental optical properties of hybrid and nanostructured materials
We harvest both solution-based synthesis and vapor-phase growth techniques to fabricate thin-film and nanostructured materials. We exploit these materials and structures are exploited for energy conversion, optoelectronics, sensing, and information science applications. Recently, we developed reflection-based techniques for measuring polarization-dependent linear optical properties of achiral and chiral two-dimensional perovskites. Our work elucidated the intrinsic chiroptical responses of these materials.
Relevant publications: Nat. Commun. 2024, 15, 2573; J. Optics 2022, 24, 044009; Phys. Rev. Lett. 2018, 121, 127401
Excited-state dynamics and optical manipulation of functional materials
We investigate the dynamic processes of fundamental excitations (e.g., electrons, lattice vibrations) in solid-state and solution-phase materials. For example, we resolve the temporal and spatial characteristics of phase transformations in soft-lattice materials. Furthermore, we use femtosecond laser pulses as an active tuning knob to probe elusive structure-property relationships in emerging materials and control their properties out of equilibrium. Our optical setups are flexible, well integrated, and routinely modified to engage with different measurements.
Relevant publications: Nanoscale 2024, 16, 5169-5176; Matter 2023, 6, 460-474; Phys. Rev. Lett. 2022, 129, 177401; Adv. Funct. Mater. 2020, 30, 1907982
We gratefully acknowledge the following funding agencies for supporting our work.
