Electronic structures and optical properties of rutile TiO2 with different point defects from DFT+U calculations

Zhu, Haiou; Zhou, Peng; Li, X.; Liu, J.-M.

doi:10.1016/j.physleta.2014.07.029

Cited by 50 publications

(23 citation statements)

References 51 publications

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“…Previous reports have been disputed about the similar effects and are attributed to the structural and electronic defects in the TiO 2 and enhanced by the nanoparticles or nanotubes doping in the donor polymer which improves the HTL in heterojunction contact to create a better synergy in the carrier separation and their collection. [17][18][19][20][21][22] External quantum efficiency (EQE) of the two efficient devices are shown in Figure 9 which is in concordance with Table 2. The measured EQE response for 1% and 5% doping concentrations of FeS 2 nanoparticles were 40% and 30%, respectively.…”

Section: Fes 2 Nanoparticlessupporting

confidence: 82%

“…The increment in the solar cell conversion efficiency could be attributed to the film quality of TiO 2 prepared by sol‐gel synthesis, which yields a mesoporous structure that could enhance the efficient charge extraction, and the nanoparticles act as a transport carrier mediator determined by its energy level. Previous reports have been disputed about the similar effects and are attributed to the structural and electronic defects in the TiO 2 and enhanced by the nanoparticles or nanotubes doping in the donor polymer which improves the HTL in heterojunction contact to create a better synergy in the carrier separation and their collection …”

Section: Resultsmentioning

confidence: 99%

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Poly‐3‐hexylthiophene doped with iron disulfide nanoparticles for hybrid solar cells

et al. 2019

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Summary In this work, the pyrite crystalline phase of iron disulfide nanoparticles (FeS2) about 20 to 30 nm was obtained by a two‐pot thermal method at 220°C. Subsequently, different concentrations of these nanoparticles were used as a doping agent for the conjugated poly‐3‐hexylthiophene (P3HT). The electrical resistivity of P3HT was decreased almost three orders of magnitude while adding FeS2 nanoparticles as doping, and dichlorobenzene solvent was a determinant factor for the dispersion of polymer with nanoparticles. Doped‐P3HT dichlorobenzene solution was spin coated onto the FTO/TiO2 substrate to fabricate the FTO/TiO2/P3HT:FeS2/C‐Au hybrid solar cells. Moreover, the power conversion efficiency (PCE) of hybrid devices was studied as a function of pyrite FeS2 nanoparticle concentration. The highest efficiency of 0.83% was obtained at 1% concentration of FeS2 nanoparticles. Hence, the results revealed that the FeS2 nanoparticles could be considered as an alternative charge carrier to develop the bulk hybrid solar cells.

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Section: Fes 2 Nanoparticlessupporting

confidence: 82%

Section: Resultsmentioning

confidence: 99%

Poly‐3‐hexylthiophene doped with iron disulfide nanoparticles for hybrid solar cells

et al. 2019

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“…The behavior of the E v energies, in relation to the increasing values of the drip rate, is exactly the opposite to the observed for the band gap values, showing a shift energy to lower values, as other authors reported for semiconductor structures exhibiting vacancies in their crystalline lattices [46][47][48]. From the PAS and UV-photoelectron spectroscopy measurements, E g and E v energies, and the conduction band minimum (CBM) are summarized in Table 4.…”

Section: Maximum Valence Band Energy Determinationmentioning

confidence: 49%

“…These optical properties depend entirely on the crystalline structure, and are strongly affected by the presence of crystalline defects, vacancies, self-interstitial atoms, and substitutional and interstitial impurity atoms. In the particular case of vacancy defects, an energy shift in valence and conduction energy bands has been observed in different materials [46][47][48], as consequence.…”

Section: Optical Propertiesmentioning

confidence: 99%

Sol–gel synthesis and characterization of calcium-deficient hydroxyapatite photocatalysts suitable for hydrogen production: influence of the drip rate in the photocatalytic activity

et al. 2019

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In the present work, the sol-gel synthesis of calcium-deficient hydroxyapatite samples is reported, under four different drip rates, to investigate their effects on their photocatalytic activity in the water splitting reaction, under UV irradiation. The results of the structural and chemical composition characterizations show that the increase in the drip rate has a negative effect on the stoichiometry, inducing significant deficiencies in the calcium and oxygen content. Likewise, the values of the band gap and valence band energies were determined, showing a correlation between them, and the deficiencies of Ca, O and OH induced by the drip rate. Finally, the photocatalytic production of hydrogen in the presence of the synthesized samples was evaluated, showing in all cases production rates much higher than that obtained by using Degussa P25 as a photocatalyst, under the same conditions.

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“…onde E gap corresponde ao valor da energia do band gap e HOM O e LU M O aos orbitais de mais alta energia ocupado e de menor energia não ocupado, respectivamente. Podemos ver que o band gap para a maioria das configurações ficou em torno de 2,60 a 2,80 eV, que é inferior aos dados existente na literatura científica (3,00 a 3,20 eV), medidos de forma empírica (24)(25)(26). O que explica os valores dos band gap que encontramos estarem abaixo do valor encontrado na literatura, se dá pelo fato do funcional PBE não ser tão bom para expressar o band gap das estruturas, uma vez que não descreve bem a distribuição de cargas no cluster.…”

Section: Densidade De Estados Dos Clusters De Tiounclassified

Propriedades estruturais e eletrônicas de clusters de (TiO2)n e (CeO2)n, n = 1-15, usando a teoria do funcional da densidade

Rosalino¹

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The use of transition metal dioxides in technological applications is wide spread, because these compounds have important characteristics of semiconductors. Although there a large number of theoretical and experimental studies, the acknowledgement about the structural and electronic properties these compounds are not yet satisfactory, especially when studying clusters. Clusters can be defined as an embryonic phase of matter, because they are particles that contain a very small number of atoms in comparison with macroscopic particles. So, the structural and electronic properties are very distinct of the material crystalline phase, when allow the development of new materials in technological applications. Therefore a large interest exist in understanding the structural and electronic properties of clusters. In this master's degree project we have as objective to study the electronic and structural properties of TiO 2 and CeO 2 clusters, using first principle calculations based on the density functional theory (DFT). One of the main problems in the study of clusters is to determine the atomic structure, due the experimental difficult of work with so small particles. Thus, a great challenge was to determine the atomic structures of these two different transition metal dioxides, considering that our group (QTnano), has a large knowledge in the development and implementation of global optimization algorithms. Due the difficulty involved in studying small particles, we were restricted to the clusters of composition (MO 2) n , with n = 1−15. In other words, our largest clusters have 45 atoms and a diameter smaller than 3 nm. Along with securing the structures, we realize the study of electronic, energetic and vibrational properties to each generated composition, providing an understanding of electronic effects in the atomic structure of clusters.

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Electronic structures and optical properties of rutile TiO2 with different point defects from DFT+U calculations

Cited by 50 publications

References 51 publications

Poly‐3‐hexylthiophene doped with iron disulfide nanoparticles for hybrid solar cells

Poly‐3‐hexylthiophene doped with iron disulfide nanoparticles for hybrid solar cells

Sol–gel synthesis and characterization of calcium-deficient hydroxyapatite photocatalysts suitable for hydrogen production: influence of the drip rate in the photocatalytic activity

Propriedades estruturais e eletrônicas de clusters de (TiO<sub>2</sub>)<sub>n</sub> e (CeO<sub>2</sub>)<sub>n</sub>, n = 1-15, usando a teoria do funcional da densidade

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