No abstract

Boehmite nanoparticles (g-AlOOH) have been successfully synthesized by the hydrothermal method at 180 8C using aluminum nitrate, Al(NO 3 ) 3 Á9H 2 O, as the aluminum source and sodium metaborate, NaBO 2 Á4H 2 O, as controlling agent. The size and morphology of boehmite nanoparticles could be controlled by adjusting the pH value of the reaction mixture. The resulting products were characterized by X-ray diffraction (XRD), Fourier transform-infrared spectra (FT-IR), scanning electron microscopy (SEM), UV-Vis spectra, and photoluminescence spectra. The electronic band structure along with density of states (DOS), obtained at the density functional theory (DFT) level indicates that g-AlOOH has a direct energy bandgap of 4.51 eV. The optical properties, including the dielectric, absorption, reflectivity, and energy-loss spectra of the compound are calculated by the DFT method and analyzed based on the electronic structures.

The ongoing quest to find methods to control the trap states in solution processed nanostructures (trap engineering) will revolutionise the applications of nanomaterials for optoelectronic purposes.

No abstract

No abstract

The hydrothermal synthesis and optical properties of undoped and Sb 3+ -doped lithium metasilicate and lithium disilicate nanomaterials were investigated. The microstructures and morphologies of the synthesized Li 2−2x Sb 2x SiO 3 and Li 2−2x Sb 2x Si 2 O 5 nanoparticles were studied with powder X-ray diffraction and scanning electron microscopy techniques, respectively. The synthesized undoped and doped lithium metasilicate and lithium disilicate nanomaterials, respectively, are isostructural with the standard bulk Li 2 SiO 3 (space group Cmc2 1 ) and Li 2 Si 2 O 5 (space group Ccc2) materials. The electronic absorption and photoluminescence spectra of the synthesized materials are studied. The measured optical properties show dependence on the dopant amounts in the structure.

UV-vis and photoluminescence spectra of the hydrothermally synthesized crystalline lithium metasilicate (Li 2 SiO 3 ) and lithium disilicate (Li 2 Si 2 O 5 ) nanomaterials are studied. The intensity of the bands in the emission spectra increases with increasing reaction time in both compounds. The electronic band structure along with density of states calculated by the density functional theory (DFT) method indicates that Li 2 SiO 3 and Li 2 Si 2 O 5 have an indirect energy band gap of 4.575 and 4.776 eV respectively. The optical properties, including the dielectric, absorption, reflectivity, and energy loss spectra of the compounds, are calculated by DFT method and analyzed based on the electronic structures.

Weak light absorption of graphene has limited the responsivity of graphene-based photodetectors. On the other hand, the slow response of PbSe as a mid-infrared range (MIR) detector makes this type of detector unsuitable as a commercial detector. Here, we report a fast MIR detector based on hybrid graphene-PbSe nanorods. For this purpose, a few-layer graphene piece was synthesized using a simple, scalable, and economical method on a cobalt layer, the synthesized graphene was transferred onto interdigitated copper electrodes, and then synthesized nanorods were spin coated on the transferred graphene. Strong and tunable light absorption in the quantum dot layer creates electric charges, which are transferred to the graphene, and due to the high charge mobility of graphene and long trapped-charge lifetimes in the quantum dot layer, they recirculate many times. The fabricated device has high speed and responsivity. The gain of fabricated detectors based on hybrid graphene quantum dots is 10.3 times more, their response time is 14.3 times faster, and their responsivity is 10 times more than conventional nanorod-based detectors. From the point of view of spectral selectivity, tuning the size of the nanorods helps optical detection from the IR to mid-IR.