Trap State Emission from TiO<sub>2</sub> Nanoparticles in Microemulsion Solutions

and, Hirendra Nath Ghosh; Adhikari, Soumyakanti

doi:10.1021/la010062i

Cited by 46 publications

(34 citation statements)

References 19 publications

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“…When compared with emission from quinine sulphate in 0.05 mol/L aqueous sulphuric acid, the emission quantum yield of TiO 2 nanocrystals prepared in our study was determined to be about 0.20, which was much higher than the values (0.001 and 0.002) reported in previous studies (14,23,26).…”

Section: Resultscontrasting

confidence: 74%

“…Specifically, a strong and stable PL emission with a maximum at 450 nm (λ ex max = 375 nm) has been observed in our study. Although similar PL spectra have been reported for TiO 2 nanocrystals previously (22,23), the high quantum yield and the fluorescence micrography of TiO 2 nanocrystals encapsulated in lipsomes are here reported for the first time. Additionally, the surface states and crystallinity of TiO 2 nanocrystals are considered as important sources of the observed luminescence.…”

supporting

confidence: 84%

“…Consequently, the surface state, i.e. the capping group and the defect states, has been shown to improve the photoluminescence quantum yield by changing the electronic state of TiO 2 nanocrystals significantly (23,26,32). On TGA-SDTA curves of TiO 2 nanocrystals, shown in Fig.…”

Section: Preparation Of Lipsomes Encapsulating Tio 2 Nanocrystalsmentioning

confidence: 99%

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High photoluminescence quantum yield of TiO₂ nanocrystals prepared using an alcohothermal method

Song

Wang

et al. 2007

Luminescence

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Highly dispersible TiO2 nanocrystals (approximately 6 nm) were prepared by an alcohothermal method. A strong and stable photoluminescence emission with a maximum at 450 nm was observed in the original TiO2 nanocrystals colloid. Compared with the emission from quinine sulphate in 0.05 mol/L sulphuric acid, the emission quantum yield of TiO2 nanocrystals was determined to be about 0.20, which was much higher than the values (0.002 and 0.001) reported in previous studies. The fluorescence micrograph of TiO2 nanocrystals encapsulated in lipsomes shows that TiO2 nanocrystals prepared in such a way have potential application as a fluorescence probe in biological imaging. Research on the luminescence mechanism indicates that the surface state and extent of crystallization of the TiO2 nanocrystals are crucial factors in the high photoluminescence quantum yield obtained in this study.

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Section: Resultscontrasting

confidence: 74%

supporting

confidence: 84%

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High photoluminescence quantum yield of TiO₂ nanocrystals prepared using an alcohothermal method

Song

Wang

et al. 2007

Luminescence

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“…This is a very low quantum yield compared to the high intrinsic quantum yield of the Eu 3 + ion, and probably caused by bad surface capping of the nanoparticles, which favors the nonradiative recombination of the exciton in the TiO 2 host. [17,18] Clearly, these quantum yields have to be improved significantly to make them really attractive for practical application. At this stage it is unknown if the Eu 3 + ions are randomly distributed over the nanoparticle or if they are preferentially located at or near the surface.…”

mentioning

confidence: 99%

Sensitized Emission in Ln³⁺‐Doped TiO₂ Semiconductor Nanoparticles

Stouwdam

Veggel

2004

ChemPhysChem

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Lanthanide-doped semiconductor nanoparticles could have advantages in polymer-based light-emitting diodes (LEDs), displays, lasers, and optical amplifiers. These materials would offer the advantages of lanthanide luminescence combined with the generation of light directly from electrical current, for instance, in polymer LEDs.[1] Lanthanide luminescence arises from transitions within the 4f shell of the ion, which are parity forbidden. This forbidden character leads to long luminescent lifetimes and low absorptions. The long luminescence lifetimes of the lanthanide ions has a clear advantage in applications where population inversion is required, such as in lasers and optical amplifiers. Energy transfer from the excited semiconductor host to the lanthanide ion could be an efficient way to circumvent the low absorption of the ion and to give the possibility of excitation with electrical current. Semiconductor nanoparticles that are dispersible in organic solvents have been prepared and attempts have been made to dope these particles with lanthanide ions. The doping of lanthanide ions in semiconductor nanoparticles has mainly been focused on II±VI semiconductors, such as ZnS, CdS, and CdSe. However, to date no convincing evidence has been shown that this was successful.[2] Direct evidence can be found in the excitation spectrum of the lanthanide emission, in which not only the absorption peaks of the lanthanide ions should be present, but also the absorption of the semiconductor host, thereby clearly demonstrating the energy transfer of the semiconductor host to the lanthanide ion. Raola and Strouse reported the doping of Eu 3 + ions in CdSe nanoparticles, but no luminescence studies were performed.[3] They introduced the europium in the form of Eu 2 + and found with X-ray photoelectron spectroscopy that after work-up the oxidation state was Eu(iii). Difficulties in doping most likely arise from the large difference in the size of the host cation and the lanthanide ion, the charge mismatch between the cations, and the low affinity of the lanthanide ions towards sulfur and selenium. Lanthanide ions do have a high affinity for oxygen and, herein, the successful doping of lanthanide ions in the oxygen-based semiconductor TiO 2 and energy transfer from the semiconductor to the dopant Ln 3 + ion is presented.The thermal decomposition of organometallic precursors in trioctylphosphine oxide (TOPO) is a well-developed synthesis route to obtain II±VI semiconductor nanoparticles.[4] Recently, the synthesis of TiO 2 particles in TOPO by the high-temperature decomposition of [Ti(OPr i ) 3 (dmae)] ( i Pr = isopropyl; dmae = dimethylaminoethoxide) was also described.[5] This procedure was modified to obtain lanthanide-ion-doped TiO 2 nanoparticles.An FTIR spectrum was measured of nanoparticles dried under vacuum over P 2 O 5 at 80 8C (Figure 1). A broad band centered at 3300 cm À1 was found, which can be ascribed to the Figure 1. FTIR spectrum of TOPO-capped TiO 2 :Eu particles in KBr. The spectrum was measured on a Perkin Elmer...

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“…Presence of a large amount of surface defects gives rise to high speed of surface recombination. As a result, the TiО 2 luminescence photoresponse does not exceed 0.002 [38]. Luminescence of NaOH in aqueous solution with titanates prevents to research TiО 2 luminescence.…”

Section: Luminescencementioning

confidence: 99%

Hydrothermal synthesis and properties of titania nanotubes doped with Fe, Ni, Zn, Cd, Mn

Kulish¹

2011

Semicond. Phys. Quantum Electron. Optoelectron.

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Abstract. Fe/TiO 2 , Mn/TiO 2 , Zn/TiO 2 , Cd/TiO 2 , Ni/TiO 2 titania nanotubes were synthesized by the method of direct hydrothermal synthesis. Their properties have been investigated using X-ray phase analysis and X-ray fluorescent analysis, high-resolution transmission electron microscopy, luminescent spectroscopy and Raman scattering. It has been ascertained that the Fe/TiO 2 , Mn/TiO 2 , Zn/TiO 2 , TiO 2 titania nanotubes possess the structure of Na 2 Ti 2 O 4 (OH) 2 . The structure of Cd/TiO 2 titania, probably, is mixture of anatase and rutile phases. We have found that Fe, Mn, Zn, Cd, Ni does not form solid solution with TiO 2 , and these metals are located in interlayer space. The mechanism of nanotube formation has been briefly discussed.

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Trap State Emission from TiO₂ Nanoparticles in Microemulsion Solutions

Cited by 46 publications

References 19 publications

High photoluminescence quantum yield of TiO₂ nanocrystals prepared using an alcohothermal method

High photoluminescence quantum yield of TiO₂ nanocrystals prepared using an alcohothermal method

Sensitized Emission in Ln³⁺‐Doped TiO₂ Semiconductor Nanoparticles

Hydrothermal synthesis and properties of titania nanotubes doped with Fe, Ni, Zn, Cd, Mn

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Trap State Emission from TiO2 Nanoparticles in Microemulsion Solutions

Cited by 46 publications

References 19 publications

High photoluminescence quantum yield of TiO2 nanocrystals prepared using an alcohothermal method

High photoluminescence quantum yield of TiO2 nanocrystals prepared using an alcohothermal method

Sensitized Emission in Ln3+‐Doped TiO2 Semiconductor Nanoparticles

Hydrothermal synthesis and properties of titania nanotubes doped with Fe, Ni, Zn, Cd, Mn

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Product

Resources

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Trap State Emission from TiO₂ Nanoparticles in Microemulsion Solutions

High photoluminescence quantum yield of TiO₂ nanocrystals prepared using an alcohothermal method

High photoluminescence quantum yield of TiO₂ nanocrystals prepared using an alcohothermal method

Sensitized Emission in Ln³⁺‐Doped TiO₂ Semiconductor Nanoparticles