Tight binding modeling of CdSe/ZnS and CdZnS/CdS II–VI heterostructures for solar cells: Role of d-orbitals

Gürel, H. Hakan; Akıncı, Özden; Ünlü, Hilmi

doi:10.1016/j.tsf.2007.12.101

Cited by 19 publications

(8 citation statements)

References 13 publications

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“…Figure 1 shows the band structure of CdSe bulk computed with the above TB parameters (a) compared to the band structure obtained in DFT calculation (b), in which the conduction band was rigidly shifted by 1.562 eV to reproduce the experimental value of the gap. Note that in our parametrization the on-site energies of d orbitals on both the anion and the cation are above the energies of orbitals s and p. This is in contrast to several other parametrizations accounting for the d orbitals, [67][68][69] where the cation d orbitals lie below the s and p orbitals. In such parametrizations it is possible to reproduce the flat d-band visible in Fig.…”

Section: A Atomistic Tight-binding Description Of a Nanocrystalmentioning

confidence: 78%

Fine structure and size dependence of exciton and biexciton optical spectra in CdSe nanocrystals

2010

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Theory of electronic and optical properties of exciton and bi-exciton complexes confined in CdSe spherical nanocrystals is presented. The electron and hole states are computed using atomistic sp 3 d 5 s * tight binding Hamiltonian including an effective crystal field splitting, spin-orbit interactions, and model surface passivation. The optically excited states are expanded in electron-hole configurations and the many-body spectrum is computed in the configuration-interaction approach. Results demonstrate that the low-energy electron spectrum is organized in shells (s, p, . . . ), whilst the valence hole spectrum is composed of four low-lying, doubly degenerate states separated from the rest by a gap. As a result, the bi-exciton and exciton spectrum is composed of a manifold of closely lying states, resulting in a fine structure of exciton and bi-exciton spectra. The quasi-degenerate nature of the hole spectrum results in a correlated bi-exciton state, which makes it slowly convergent with basis size. We carry out a systematic study of the exciton and bi-exciton emission spectra as a function of the nanocrystal diameter and find that the interplay of repulsion between constituent excitons and correlation effects results in a change of the sign of bi-exciton binding energy from negative to positive at a critical nanocrystal size.

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Section: A Atomistic Tight-binding Description Of a Nanocrystalmentioning

confidence: 78%

Fine structure and size dependence of exciton and biexciton optical spectra in CdSe nanocrystals

2010

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“…Cd 1−x Zn x S is a wide bandgap n-type semiconductor having strong potential as a window material in heterojunction solar cells with a p-type absorber layer like CuInSe 2 [1][2][3]. Moreover, Cd 1−x Zn x S is approximate window layer material without lattice mismatch.…”

Section: Introductionmentioning

confidence: 99%

The electronic band parameters calculated by the Kronig–Penney method for Cd1−xZnxS quantum dot superlattices

Sakly

Safta²,

Mejri³

et al. 2009

Journal of Alloys and Compounds

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“…This is principally due to their utility as window materials in heterojunction solar cells with a p-type absorber such as CuInSe 2 , CuIn x Ga 1-x Se 2 or CuSnS z Se 1-z [4][5][6][7][8][9].…”

Section: Introductionmentioning

confidence: 99%

The Energy Levels Splitting Calculated for the Heavy and Light Holes in a Cd<sub>1-x</sub>Zn<sub>x</sub>S Double Quantum Dot

Khéfacha¹

2017

NANO

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Abstract:This work reports on a theoretical investigation of a double Cd 1-x Zn x S quantum dot embedded in an insulating material.The quantum dots are assumed to have a flattened cylindrical geometry with a finite barrier at the boundary.The energy levels splitting has been computed, using the tight binding approximation, in the case of the heavy and light holes, as a function of zinc composition for different inter-quantum dot separations. An analysis of the results shows that, for the light holes, the coupling is maximum when x=0.8. Moreover, it has been demonstrated the strong localization character of the heavy holes in this nanostructure.

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Tight binding modeling of CdSe/ZnS and CdZnS/CdS II–VI heterostructures for solar cells: Role of d-orbitals

Cited by 19 publications

References 13 publications

Fine structure and size dependence of exciton and biexciton optical spectra in CdSe nanocrystals

Fine structure and size dependence of exciton and biexciton optical spectra in CdSe nanocrystals

The electronic band parameters calculated by the Kronig–Penney method for Cd1−xZnxS quantum dot superlattices

The Energy Levels Splitting Calculated for the Heavy and Light Holes in a Cd<sub>1-x</sub>Zn<sub>x</sub>S Double Quantum Dot

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Tight binding modeling of CdSe/ZnS and CdZnS/CdS II–VI heterostructures for solar cells: Role of d-orbitals

Cited by 19 publications

References 13 publications

Fine structure and size dependence of exciton and biexciton optical spectra in CdSe nanocrystals

Fine structure and size dependence of exciton and biexciton optical spectra in CdSe nanocrystals

The electronic band parameters calculated by the Kronig–Penney method for Cd1−xZnxS quantum dot superlattices

The Energy Levels Splitting Calculated for the Heavy and Light Holes in a Cd&lt;sub&gt;1-x&lt;/sub&gt;Zn&lt;sub&gt;x&lt;/sub&gt;S Double Quantum Dot

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The Energy Levels Splitting Calculated for the Heavy and Light Holes in a Cd<sub>1-x</sub>Zn<sub>x</sub>S Double Quantum Dot