Research Highlights

Thermal transport measurement and imaging

We demonstrated a time-resolved optical technique called vibrational-pump visible-probe (VPVP) spectroscopy, which employs direct vibrational excitation of materials by fs mid-infrared (MIR) optical pump, after which the time dependent optical transmittance across the visible range is probed in the ns to the µs time window using a broadband pulsed laser. This transducer-free VPVP method is expected to permit the investigation of dynamic lattice temperature variations in organic, polymeric, and hybrid organic-inorganic semiconductors.

Relevant publications: Review of Scientific Instruments 2022, 93, 053003; The Journal of Physical Chemistry C 2023, 127, 3523-3531;

Optical properties of nanostructured materials

We harvest both solution-based synthesis and vapor-phase growth techniques to fabricate thin-film and nanostructured materials. These materials and structures are exploited for energy conversion, optoelectronics, sensing, and information science applications. We are particularly interested in layered hybrid organic-inorganic perovskites and other classes of low-dimensional materials.

Relevant publications: Journal of Optics 2022, 24, 044009; Nature Communications 2018, 9, 2019; Physical Review Letters 2018, 121, 127401;

Excited-state dynamics of functional materials

We investigate the dynamic processes of fundamental excitations (e.g., electrons, lattice vibrations) in solid-state and solution-phase materials using time-resolved optical spectroscopy. Our spectroscopic setup covers a wide spectral range (250 nm ~ 15 µm) with ~100 fs time resolution and diffraction-limited spatial resolution.

Relevant publications: Physical Review Letters 2022, 129, 177401; Nature Communications 2018, 9, 2792; Nature Photonics 2016, 10, 267-273;

Optical manipulation of materials

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. To this end, we combine ultrafast excitation (electronic or vibrational) with time-resolved absorption, luminescence and Raman measurements of materials at controlled environments. Our optical setups are flexible, well integrated, and routinely modified to engage with different measurements.

Relevant publications: Matter 2023, 6, 460-474; Advanced Functional Materials 2020, 30, 1907982; Nature Communications 2019, 10, 482;

We gratefully acknowledge the following funding agencies for supporting our work.