The
relatively weak Raman enhanced factors of semiconductor-based
substrate limit its further application in surface-enhanced Raman
scattering (SERS). Here, a kind of two-dimensional (2D) semimetal
material, molybdenum carbide (Mo2C) film, is prepared via
a chemical vapor deposition (CVD) method, and the origin of SERS is
investigated for the first time. The detection limits of the prepared
Mo2C films for crystal violet (CV) and rhodamine 6G (R6G)
molecules are low at 10–6 M and 10–8 M, respectively. Our detailed theoretical analysis, based on density
functional theory and the finite element method, demonstrates that
the enhancement of the 2D Mo2C film is indeed CM in nature
rather than the EM effects. Besides, the basic doping strategies are
proposed to further optimize the SERS sensitivity of Mo2C for Fermi level regulation. We believe this work will provide a
helpful guide for developing a highly sensitive semimetal SERS substrate.
The coordination of piezoelectric and plasmonic effects to regulate the separation and migration of photo-generated carriers is still a significant method to improve the performance of visible-light photoresponse. Herein, we propose the PVDF@Ag-ZnO/Au composite nanofiber membranes utilizing the piezoelectric and plasmonic effects to promote the photocatalytic degradation of organic dyes. Here, ZnO nanorods can generate a built-in electric field under vibration to separate electron-hole pairs. The Schottky junction formed by noble metal/semiconductor can not only inhibit the recombination of photo-generated carriers and accelerate the migration of carriers, but also enhance the utilization of visible light. In addition, the structure has excellent flexibility and easy recycling characteristics. We demonstrate that the plasmonic effect of noble metal can enhance the light response of membranes and broaden light absorption from ultraviolet to visible light region. With the help of the surface-enhanced Raman scattering (SERS), modulation effects of the piezoelectric effect on light response is proved. For catalytic processes, rhodamine B (98.8%) can be almost completely degraded using PVDF@Ag-ZnO/Au within 120 minutes in the piezoelectric photocatalysis process, which is 2.2 and 2.8 times higher than photocatalysis and piezoelectric catalysis, respectively. This work provides a promising strategy for harnessing solar and mechanical energy.
Interface modification is an important way to get better performance from organic solar cells (OSCs). A natural biomolecular material methionine was successfully applied as the electron transport layer (ETL) to the inverted OSCs in this work. A series of optical, morphological, and electrical characterizations of thin films and devices were used to analyze the surface modification effects of methionine on zinc oxide (ZnO). The analysis results show that the surface modification of ZnO with methionine can cause significantly reduced surface defects for ZnO, optimized surface morphology of ZnO, improved compatibility between ETL and the active layer, better-matched energy levels between ETL and the acceptor, reduced interface resistance, reduced charge recombination, and enhanced charge transport and collection. The power conversion efficiency (PCE) of OSCs based on PM6:BTP-ec9 was improved to 15.34% from 14.25% by modifying ZnO with methionine. This work shows the great application potential of natural biomolecule methionine in OSCs.
MAPbBr3 quantum dots in SiO2 mesopores ([Formula: see text][Formula: see text]nm) were prepared by the spin-coating method, and their luminescence and nonlinear optical properties were studied by time-resolved photoluminescence (TRPL) and Z-scan techniques. The results showed that the absorption and photoluminescence peaks are at 464[Formula: see text]nm and 476[Formula: see text]nm, respectively. The TRPL spectroscopy showed two relaxation processes, a short lifetime (1.04[Formula: see text]ns) and a long lifetime (4.49[Formula: see text]ns), attributed to the trap–capture recombination and the electron–hole radiative recombination, respectively. Two-photon absorption (TPA) coefficient was 529[Formula: see text]cm/GW at 800[Formula: see text]nm. The nonlinear signal changed from TPA to saturable absorption with increase in light intensity.
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