Photoluminescence from colloids containing aluminum hydroxide nanocrystals with uniform size

Abstract

Aluminum hydroxide nanocrystals consisting of an amorphous shell and crystalline core are fabricated by pulsed laser ablation of an aluminum target in water. The colloid consisting of nanocrystals with a uniform size exhibits a size-independent photoluminescence ͑PL͒ band at ϳ383 nm. According to the PL excitation spectra and time-resolved PL decay analysis, this PL band originates from oxygen vacancies in the amorphous shell and Förster energy transfer occurs between the oxygen vacancy levels in the crystalline core and amorphous shell. These phenomena are found to alter the PL excitation spectra.

Mesoporous Aluminum Hydroxide Synthesized by a Single‐Source Precursor‐Decomposition Approach as a High‐Quantum‐Yield Blue Phosphor for UV‐Pumped White‐Light‐Emitting Diodes

“…It is thus an important topic of the contemporary materials research to identify alternative rare‐earth free phosphors, low cost and with a wider PL spectrum for a higher CRI. In respect to the latter requirement, aluminum hydroxides, which exist in a number of structures such as trihydroxides (Al(OH) 3 ), monohydroxides (AlOOH), and 5Al 2 O 3 ·2H 2 O, show a wide PL spectrum (FWHM of ≈100 nm) in the blue region which makes them attractive candidates as the down‐converting blue phosphors in UV‐WLEDs. Aluminum hydroxides also benefit from low cost and the earth‐abundance, high stability, and low toxicity.…”

Single Source Precursor Chemical Vapor Decomposition Method to Fabricate Stable, Bright Emissive Aluminum Hydroxide Phosphors for UV‐Pumped White Light‐Emitting Devices

“…Aluminum hydroxide, a very common, low‐cost intermediate compound in aluminum and aluminum oxide industry, exhibits different stable structures (Al(OH) 3 , AlOOH, 5Al 2 O 3 3H 2 O) and has been applied in plenty of fields including flame retardants, catalysis, waste treatment, medical and petrochemical industries . In recent years, different kinds of nanosized aluminum hydroxides such as γ‐AlOOH nanotubes, nanorods, nanoplates, nanofibers, nanobelts, nanoparticles, and nanowires, as well as Al(OH) 3 nanocrystals (NCs), have been reported. As demonstrated in previous works, their PL in ultraviolet and blue spectral regions originates from F + centers (oxygen vacancies occupied by one electron) or/and F centers (oxygen vacancies occupied by two electrons), which have low molar extinction coefficients resulting in low probability of electron–hole radiative recombination and thus rather low emission efficiency.…”

“…In recent years, different kinds of nanosized aluminum hydroxides such as γ‐AlOOH nanotubes, nanorods, nanoplates, nanofibers, nanobelts, nanoparticles, and nanowires, as well as Al(OH) 3 nanocrystals (NCs), have been reported. As demonstrated in previous works, their PL in ultraviolet and blue spectral regions originates from F + centers (oxygen vacancies occupied by one electron) or/and F centers (oxygen vacancies occupied by two electrons), which have low molar extinction coefficients resulting in low probability of electron–hole radiative recombination and thus rather low emission efficiency. Thus, efforts have been done to enhance the PL of aluminum hydroxide.…”

“…Thus, efforts have been done to enhance the PL of aluminum hydroxide. Chu group fabricated Al(OH) 3 NCs by using pulsed laser ablation of an aluminum target in water and demonstrated that their PL band at 383 nm arises from Förster energy transfer between the oxygen vacancy levels in the amorphous shell and crystalline core. Bai et al used solvothermal benzyl alcohol route to fabricate γ‐AlOOH hybrid nanoplates modified with high extinction coefficient organic light‐harvesting species (benzoate ligands) linked to the surface to sensitize the F + emission centers, so that their PL QY could be enhanced to 38–58%.…”

Optical identification of oxygen vacancy types in SnO2 nanocrystals

“…18 The white powders prepared by pulsed laser ablation were annealed at T a ¼ 0 C (sample B) and 400 C (sample C) in an oxygen ambient for 6 h. Sample A was prepared by a hydrothermal reaction involving SnCl 4 Á5H 2 O and CO(NH 2 ) 2 in an autoclave at 90 C for 5 h. After the reaction, the autoclave was cooled to room temperature naturally. The white precipitates were centrifuged and rinsed thoroughly with water several times and then dried in an oven at 40 C. The materials were characterized by highresolution transmission electron microscopy (HR-TEM, JEOL-2100), Raman scattering, ultraviolet/visible absorption, and PL (excited by 325 nm laser).…”