Defects activated photoluminescence in two-dimensional semiconductors: interplay between bound, charged and free excitons

Tongay, Sefaattin; Suh, Joonki; Ataca, Can; Fan, Wen; Luce, Alexander; Kang, Je-Won; Liu, Jonathan; Ko, Changhyun; Raghunathanan, Rajamani; Zhou, Jian; Ogletree, Frank; Li, Jingbo; Grossman, Jeffrey C.; Wu, Junqiao

doi:10.1038/srep02657

Cited by 974 publications

(1,111 citation statements)

References 25 publications

(28 reference statements)

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“…As the temperature increases fur-ther, sudden quenching occurs and decreases the peak intensity. The observed results were consistent with the theories explained by Tongay et al, 2013. Moreover, when the sample is heated to a higher temperature, cellulose molecules break down and hydro gen passivation takes place, resulting in a decrease in intensity with an increase in ion fluence (Pikulev, Loginova, & Gurtov, 2012). In addition, new peaks were observed between 540 and 657 nm in the implanted samples (5e15 and 1e16).…”

Section: Photoluminescencesupporting

confidence: 80%

“…The reason behind the for-mation of new peak on implantation is very similar to the thermal annealing effect. These results were previously proved by compar-ing the photoluminescence of irradiation and thermal annealing (Tongay et al, 2013). Hence, the scaffolds with interesting lumi-nescent properties could be used in bone tissue engineering and the imaging applications.…”

Section: Photoluminescencementioning

confidence: 55%

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Surface stiffening and enhanced photoluminescence of ion implanted cellulose – polyvinyl alcohol – silica composite

Shanthini

Sakthivel

Menon

et al. 2016

Carbohydrate Polymers

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Novel Cellulose (Cel) reinforced polyvinyl alcohol (PVA)-Silica (Si) composite which has good stability and in vitro degradation was prepared by lyophilization technique and implanted using N 3+ ions of energy 24 keV in the fluences of 1 × 10 15 , 5 × 10 15 and 1 × 10 16 ions/cm 2 . SEM analysis revealed the formation of microstructures, and improved the surface roughness on ion implantation. In addition to these structural changes, the implantation significantly modified the luminescent, thermal and mechanical properties of the samples. The elastic modulus of the implanted samples has increased by about 50 times compared to the pristine which confirms that the stiffness of the sample surface has increased remarkably on ion implantation. The photoluminescence of the native cellulose has improved greatly due to defect site, dangling bonds and hydrogen passivation. Electric conductivity of the ion implanted samples was improved by about 25%. Hence, low energy ion implantation tunes the mechanical property, surface roughness and further induces the formation of nano structures. MG63 cells seeded onto the scaffolds reveals that with the increase in implantation fluence, the cell attachment, viability and proliferation have improved greatly compared to pristine. The enhancement of cell growth of about 59% was observed in the implanted samples compared to pristine. These properties will enable the scaffolds to be ideal for bone tissue engineering and imaging applications.

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Section: Photoluminescencesupporting

confidence: 80%

Section: Photoluminescencementioning

confidence: 55%

Surface stiffening and enhanced photoluminescence of ion implanted cellulose – polyvinyl alcohol – silica composite

Shanthini

Sakthivel

Menon

et al. 2016

Carbohydrate Polymers

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“…According to previous studies, defects at the edges and the GBs may contribute the enhancement of PL intensity. New sub-bandgap emission peak as well as increase in overall PL intensity were found as a result of the vacancy generation 35 via a defect-assisted process 36 . Here, our results also imply that a local interaction also plays an important role in the PL variations.…”

Section: Structural Heterogeneity In Cvd-grown Mos 2 Monolayersmentioning

confidence: 99%

Strain and structure heterogeneity in MoS2 atomic layers grown by chemical vapour deposition

et al. 2014

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Monolayer molybdenum disulfide (MoS 2 ) has attracted tremendous attention due to its promising applications in high-performance field-effect transistors, phototransistors, spintronic devices and nonlinear optics. The enhanced photoluminescence effect in monolayer MoS 2 was discovered and, as a strong tool, was employed for strain and defect analysis in MoS 2 . Recently, large-size monolayer MoS 2 has been produced by chemical vapour deposition, but has not yet been fully explored. Here we systematically characterize chemical vapour deposition-grown MoS 2 by photoluminescence spectroscopy and mapping and demonstrate non-uniform strain in single-crystalline monolayer MoS 2 and strain-induced bandgap engineering. We also evaluate the effective strain transferred from polymer substrates to MoS 2 by three-dimensional finite element analysis. Furthermore, our work demonstrates that photoluminescence mapping can be used as a non-contact approach for quick identification of grain boundaries in MoS 2 .

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“…Vacancy defects, which can be created by thermal annealing and α particles 14 or electron beam irradiation 15 , form localized trap states in the bandgap region, leading to light emission at energies lower than the interband optical transition energy 14 . On the other hand, the observed charge mobility in single-layer MoS 2 is surprisingly low compared to bulk sample 3,6 , indicating that the charge carrier scattering by structural defects, such as vacancies and grain boundaries, may be a primary source for such a low mobility 14,16,17 . Hong et al 18 have studied point defects and their concentrations for several samples of MoS 2 by means of different preparation methods.…”

Section: Introductionmentioning

confidence: 99%

Atomic defect states in monolayers of MoS2 and WS2

Salehi

Saffarzadeh

2016

Surface Science

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The influence of atomic vacancy defects at different concentrations on electronic properties of MoS 2 and WS 2 monolayers is studied by means of Slater-Koster tight-binding model with non-orthogonal sp 3 d 5 orbitals and including the spin-orbit coupling. The presence of vacancy defects induces localized states in the bandgap of pristine MoS 2 and WS 2 , which have potential to modify the electronic structure of the systems, depending on the type and concentration of the defects. It is shown that although the contribution of metal (Mo or W) d orbitals is dominant in the formation of midgap states, the sulphur p and d orbitals have also considerable contribution in the localized states, when metal defects are introduced. Our results suggest that Mo and W defects can turn the monolayers into p-type semiconductors, while the sulphur defects make the system a n-type semiconductor, in agreement with ab initio results and experimental observations.

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Defects activated photoluminescence in two-dimensional semiconductors: interplay between bound, charged and free excitons

Cited by 974 publications

References 25 publications

Surface stiffening and enhanced photoluminescence of ion implanted cellulose – polyvinyl alcohol – silica composite

Surface stiffening and enhanced photoluminescence of ion implanted cellulose – polyvinyl alcohol – silica composite

Strain and structure heterogeneity in MoS2 atomic layers grown by chemical vapour deposition

Atomic defect states in monolayers of MoS2 and WS2

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