Research Highlights

Transducer-free, pump-probe technique for thermal conductivity measurements

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.

Nanostructured materials growth and design

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: Nature Communications, 2018, 9, 2019; Physical Review Letters, 2018, 121, 127401

Excited-state dynamics and flow of energy

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: 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: Nature Communications, 2019, 10, 482; Nature Communications, 2016, 7, 12892; Advanced Functional Materials, 2020, 30, 1907982