Interlayer vibrations launching by ultrafast laser actions

• Ultrafast spectroscopic study revealed the key role of optical property in the generation and detection of photoinduced strain waves, whose confinement initiated coherent interlayer vibrations. 

• The frequency and lifetime of the interlayer vibrations could be quantitatively explained with a linear chain and an acoustic mismatch model.

• With this scheme, we can quantitatively evaluate the elastic coupling between bottom layer and substrate with ranging from 0 (free-standing) - 2 (tightly bounding)

Coherent control of interlayer vibrations in Bi2Se3 van der Waals thin-films, TGPark et al., Nanoscale (2021).

Ultrafast formation of quantized interlayer vibrations in Bi2Se3 by photoinduced strain waves, TGPark et al., Opt. Express (2022).

Metallic TMDC can enhance optical property of Dirac materials

• Transient reflection showed the interlayer electron transfer across the vdW interface, 

• Interlayer coupling can enhance optical properties of Dirac materials in ultrabroadband spectrum within ultrafast timescale. 

• Coherent phonon spectroscopy revealed the mechanical properties (sound velocity, acoustic impedance) as well as elastic coupling with substrate.

Ultrafast interfacial carrier dynamics and persistent topological surface states of Bi2Se3 in heterojunctions with VSe2, TGPark et al., Commun. Phys. (2022).

Interlayer coupling and ultrafast hot electron transfer dynamics in metallic VSe2/graphene van der waals heterostructures, TGPark et al., ACS Nano (2021).

*Featured in The JoongAng

Ultrafast tracking of charge transport in perovskite solarcells 

• THz spectroscopy can record the electrical property of charge carriers under photoexcitation such as carrier density, mobility, and diffusion lengths.

• Ultrafast optical approach revealed the enhancement of electrical property under chemical composition tuning with non-contact manner.

Efficient perovskite solar cells via improved carrier management, J. J. Yoo et al., Nature (2021). (journal cover)

*link to KRICT-Perovskite