Ultrafast carrier dynamics of Cu₂O thin film induced by two-photon excitation*

Abstract

Cuprous oxide (Cu2O) has attracted plenty of attention for potential nonlinear photonic applications due to its superior third-order nonlinear optical property such as two-photon absorption. In this paper, we investigated the two-photon excitation induced carrier dynamics of a Cu2O thin film prepared by radio-frequency magnetron sputtering, using the femtosecond transient absorption experiments. Biexponential dynamics including an ultrafast carrier scattering (< 1 ps) followed by a carrier recombination (> 50 ps) were observed. The time constant of carrier scattering under two-photon excitation is larger than that under one-photon excitation, due to the different transition selection rules and smaller absorption coefficient of the two-photon excitation.

Plasmon‐Assisted Operando Self‐Healing of Cu2O Photocathodes

“…The optical properties of copper oxides, including cuprous oxide or cuprite (Cu 2 O) and cupric oxide (CuO), vary significantly from one sample to the next one. These properties, especially the bandgap energies, depend strongly on the synthesis process (radio-frequency magnetron sputtering, [41] electrodeposition, [40,42] oxidation of Cu in a furnace, [43] nanocrystal morphology-nanorods, [43] and quantum confinement effects [44] ). Reported values of bandgap energies range from 2-2.5 eV for Cu 2 O to 1.2-2.16 eV for CuO.…”

“…The work functions were measured using Kelvin probe microscopy (Table S1, Supporting Information) to be equal to 5.3 and 5.5 eV for the plasma-treated and pristine Cu 2 O samples, respectively. The work function of Cu was taken to be 4.5 eV, [69] the electron affinity of Cu 2 O as 3.2 eV, [70] and the band-gap of Cu 2 O as 2.2-2.4 eV, [40,41,51] a value that is consistent with the Tauc plot analysis conducted on pristine Cu 2 O samples (Figure S4, Supporting Information), where a band-gap value for pristine Cu 2 O was found to be 2.35 eV. Thus, as seen in the band diagram with accurate scaling, Cu 2 O is confirmed to be a p-doped semiconductor, and the work function of Cu is slightly below the reversible hydrogen electrode potential.…”

Grid connected frequency control method of AC excitation variable speed constant frequency wind turbine

“…With the development of UHV power grid and large-scale continuous grid connection of new energy, UHV AC hybrid power grid has gradually formed, and the changes of power grid pattern and power supply structure have also led to profound changes in power grid characteristics. Under the background of high-permeability new energy access and large-capacity AC transmission feed, the operating conditions of large-scale wind power grid connection are more complex, and some new grid connection problems begin to highlight, such as the decline of system moment of inertia, the decline of anti disturbance ability Reduced frequency and voltage regulation capacity, etc [6] . Therefore, the revision of the standard is put on the agenda.…”