Redirecting focus in CuInSe<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msub><mml:mrow /><mml:mn>2</mml:mn></mml:msub></mml:math>research towards selenium-related defects

Oikkonen, L. E.; Ganchenkova, Mariya G.; Seitsonen, Ari P.; Nieminen, Risto M.

doi:10.1103/physrevb.86.165115

Cited by 29 publications

(19 citation statements)

References 26 publications

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“…Therefore, the presence of another defect does not alter much the potential energy surface experienced by the other one. This behavior is very different from what has been shown for the most common intrinsic-type defect complexes in CIS, for which the nearest-neighbor configuration is energetically clearly preferred over longer separation distances 22 . Cluster formation may also be kinetically aided or hindered by the barriers of migration in the vicinity of defects.…”

Section: Complexcontrasting

confidence: 91%

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Effect of sodium incorporation into CuInSe2 from first principles

Oikkonen

Ganchenkova

Seitsonen

et al. 2013

Journal of Applied Physics

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The presence of small amounts of sodium has been shown to improve the electronic performance of Cu(In,Ga)Se-2 (CIGS) solar cells, but the origins of this effect have not yet been fully resolved. In this work, we have addressed the questions involving the role of sodium in CuInSe2 (CIS) using densityfunctional-theory-based calculations. We find no direct way how the creation of Na-related point defects in bulk CIS would enhance p-type conductivity. Instead, we demonstrate that Na reduces copper mass transport due to the capture of copper vacancies by Na-Cu defects. This finding provides an explanation for experimental measurements where the presence of Na has been observed to decrease copper diffusion. The suggested mechanism can also impede V-Cu-related cluster formation and lead to measurable effects on defect distribution within the material. The presence of small amounts of sodium has been shown to improve the electronic performance of Cu(In,Ga)Se 2 (CIGS) solar cells, but the origins of this effect have not yet been fully resolved. In this work, we have addressed the questions involving the role of sodium in CuInSe 2 (CIS) using density-functional-theorybased calculations. We find no direct way how the creation of Na-related point defects in bulk CIS would enhance p-type conductivity. Instead, we demonstrate that Na reduces copper mass transport due to the capture of copper vacancies by Na Cu defects. This finding provides an explanation for experimental measurements where the presence of Na has been observed to decrease copper diffusion. The suggested mechanism can also impede V Cu -related cluster formation and lead to measurable effects on defect distribution within the material.Effect of sodium incorporation into CuInSe 2 from first principles Effect of sodium incorporation into CuInSe 2 from first

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Section: Complexcontrasting

confidence: 91%

“…For all considered complexes, the values for E b do not practically depend on the exchangecorrelation functional used, but are very sensitive to the supercell size 22 . In this work, the binding energies have therefore been computed in a 512-atom supercell employing PBE-GGA.…”

Section: Methodsmentioning

confidence: 98%

Effect of sodium incorporation into CuInSe2 from first principles

Oikkonen

Ganchenkova

Seitsonen

et al. 2013

Journal of Applied Physics

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“…combining DFT with exact exchange from the Hartree-Fock method, at short distances) in our calculations, more specifically the HSE06 functional 14 . For similar reasons, the HSE06 functional has previously been employed in first-principles studies on CIGS by L. E. Oikkonen et al 15 , J. Pohl et al 16 and B. Huang et al 17 . We start our study elaborating on how the band gap changes from around 1.0 eV for CIS to 1.7 eV for CGS (as measured in optical measurements, e.g.…”

Section: Introductionmentioning

confidence: 99%

Native point defects in CuIn_1−xGa_xSe₂: hybrid density functional calculations predict the origin of p- and n-type conductivity

Bekaert

Saniz

Partoens

et al. 2014

Phys. Chem. Chem. Phys.

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“…26,27 Each defect has been considered in its relevant charge state. 24,28 The formation energies are sensitive to the stoichiometry of the material and, in the case of charged defects, also to the Fermi level position l e .…”

Section: B Computational Detailsmentioning

confidence: 99%

Mass transport in CuInSe2 from first principles

Oikkonen

Ganchenkova

Seitsonen

et al. 2013

Journal of Applied Physics

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The wide scatter in experimental results has not allowed drawing solid conclusions on selfdiffusion in the chalcopyrite CuInSe2 (CIS). In this work, the defect-assisted mass transport mechanisms operating in CIS are clarified using first-principles calculations. We present how the stoichiometry of the material and temperature affect the dominant diffusion mechanisms. The most mobile species in CIS is shown to be copper, whose migration proceeds either via copper vacancies or interstitials. Both of these mass-mediating agents exist in the material abundantly and face rather low migration barriers (1.09 and 0.20 eV, respectively). Depending on chemical conditions, selenium mass transport relies either solely on selenium dumbbells, which diffuse with a barrier of 0.24 eV, or also on selenium vacancies whose diffusion is hindered by a migration barrier of 2.19 eV. Surprisingly, indium plays no role in long-range mass transport in CIS; instead, indium vacancies and interstitials participate in mechanisms that promote the formation of antisites on the cation sublattice. Our results help to understand how compositional inhomogeneities arise in CIS. The wide scatter in experimental results has not allowed drawing solid conclusions on self-diffusion in the chalcopyrite CuInSe 2 (CIS). In this work, the defect-assisted mass transport mechanisms operating in CIS are clarified using first-principles calculations. We present how the stoichiometry of the material and temperature affect the dominant diffusion mechanisms. The most mobile species in CIS is shown to be copper, whose migration proceeds either via copper vacancies or interstitials. Both of these mass-mediating agents exist in the material abundantly and face rather low migration barriers (1.09 and 0.20 eV, respectively). Depending on chemical conditions, selenium mass transport relies either solely on selenium dumbbells, which diffuse with a barrier of 0.24 eV, or also on selenium vacancies whose diffusion is hindered by a migration barrier of 2.19 eV. Surprisingly, indium plays no role in long-range mass transport in CIS; instead, indium vacancies and interstitials participate in mechanisms that promote the formation of antisites on the cation sublattice. Our results help to understand how compositional inhomogeneities arise in CIS. V C 2013 American Institute of Physics. [http://dx

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Redirecting focus in CuInSe2research towards selenium-related defects

Cited by 29 publications

References 26 publications

Effect of sodium incorporation into CuInSe2 from first principles

Effect of sodium incorporation into CuInSe2 from first principles

Native point defects in CuIn_1−xGa_xSe₂: hybrid density functional calculations predict the origin of p- and n-type conductivity

Mass transport in CuInSe2 from first principles

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Redirecting focus in CuInSe2research towards selenium-related defects

Cited by 29 publications

References 26 publications

Effect of sodium incorporation into CuInSe2 from first principles

Effect of sodium incorporation into CuInSe2 from first principles

Native point defects in CuIn1−xGaxSe2: hybrid density functional calculations predict the origin of p- and n-type conductivity

Mass transport in CuInSe2 from first principles

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Native point defects in CuIn_1−xGa_xSe₂: hybrid density functional calculations predict the origin of p- and n-type conductivity