Publications de Lijie Wang | EPFL Graph Search

Band Gap Renormalization at Different Symmetry Points in Perovskites

Using ultrafast broad-band transient absorption (TA) spectroscopy of photoexcited MAPbBr3 thin films with probe continua in the visible and the mid- to deep-ultraviolet (UV) ranges, we capture the ultrafast renormalization at the fundamental gap at the R s ...

Amer Chemical Soc2024

Disentangling Thermal from Electronic Contributions in the Spectral Response of Photoexcited Perovskite Materials

Majed Chergui, Thomas Charles Henry Rossi, Malte Oppermann, Lijie Wang

Disentangling electronic and thermal effects in photoexcited perovskite materials is crucial for photovoltaic and optoelectronic applications but remains a challenge due to their intertwined nature in both the time and energy domains. In this study, we emp ...

Amer Chemical Soc2024

Giant two-photon absorption of anatase TiO2 in Au/TiO2 core-shell nanoparticles

Majed Chergui, Malte Oppermann, Lijie Wang

We report on deep-to-near-UV transient absorption spectra of core-shell Au/SiO2 and Au/TiO2 nanoparticles (NPs) excited at the surface plasmon resonance of the Au core, and of UV-excited bare anatase TiO2 NPs. The bleaching of the first excitonic transitio ...

CHINESE LASER PRESS2023

Photo- and Thermally- induced Effects on the Absorption Spectroscopy of Au/SiO2 and Au/TiO2 Core-shell Nanoparticles

Lijie Wang

Electrons generated by Landau damping of the plasmon excitation on gold nanoparticles that can be injected into an adjacent semiconductor e.g. anatase TiO2, enhancing the light harvesting capabilities of solar energy conversion devices. The understanding o ...

EPFL2022

Disentangling Light- and Temperature-Induced Thermal Effects in Colloidal Au Nanoparticles

Majed Chergui, Lijie Wang, Davood Zare

We present temperature-dependent (from room temperature to 80 degrees C) absorption spectra of Au/SiO2 core-shell nanoparticles (NPs) (core diameter: similar to 25 nm) in water in the range from 1.5 to 4.5 eV, which spans the localized surface plasmon reso ...

AMER CHEMICAL SOC2022

Slow Charge Carrier Relaxation in Gold Nanoparticles

Majed Chergui, Thomas Charles Henry Rossi, Malte Oppermann, Lars-Hendrik Mewes, Lijie Wang, Benjamin Bauer, Davood Zare

We report on ultrafast transient absorption (TA) studies of surface plasmon-excited similar to 25 nm-diameter Au nanoparticles in solution, monitoring the response of the surface plasmon resonance in the visible region (1.7-3.0 eV) and that of the inter- a ...

AMER CHEMICAL SOC2020

Cooling dynamics of electrons in MAPbBr(3) probed in the deep-UV

Majed Chergui, Thomas Charles Henry Rossi, Malte Oppermann, Peter Chen, Lijie Wang, Yu-Hsien Chiang

Transient absorption in the Visible and in the deep-UV is performed on MAPbBr(3) thin films with 3.1 eV pump excitation. The UV probe can access higher order transitions in the material exploring different high-symmetry points of the Brillouin zone. Uncorr ...

E D P SCIENCES2019

In situ coupling of Ti2O with rutile TiO2 as a core-shell structure and its photocatalysis performance

Lijie Wang, Peng Zhang

The fabrication of high-performance, low-cost photocatalysis materials, which absorb in the visible-light region, is of significance for their practical applications. A Ti2O@TiO2 (rutile) core-shell structure was fabricated through dehydrogenation and oxid ...

Royal Soc Chemistry2017