Buffer-free Cu(In,Ga)Se2-solar cells by near-surface ion implantation

Haarstrich, J.; Teichmann, Maria; Metzner, H.; Gnauck, M.; Ronning, Carsten; Wesch, W.; Rissom, T.; Kaufmann, Christian A.; Schock, Hans‐Werner; Scheumann, Volker; Mannstadt, W.

doi:10.1016/j.solmat.2013.04.009

Cited by 6 publications

(5 citation statements)

References 25 publications

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“…The CBD diffusion of Cd into the CIGS surface region is facilitated compared to CIGS layers without KF PDT, as shown by detailed analysis of XPS depth profiles. 3 Diffusion of Cd into the CIGS layer and its consequences for the formation of defects were also investigated in several other experimental [35][36][37] and theoretical [38][39][40] studies. Owing to the Cu depleted surface region of CIGS layers with KF PDT the in-diffusion of Cd leads to the formation of a high density of shallow donor type Cd Cu anti-site defects with a theoretically predicted charge transition level at less than 0.1 eV below the conduction band minimum.…”

Section: (Ii) Effect On Junction Propertiesmentioning

confidence: 99%

Unveiling the effects of post-deposition treatment with different alkaline elements on the electronic properties of CIGS thin film solar cells

Pianezzi

Reinhard

Chirilă

et al. 2014

Phys. Chem. Chem. Phys.

299

338

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Thin film solar cells with a Cu(In,Ga)Se2 (CIGS) absorber layer achieved efficiencies above 20%. In order to achieve such high performance the absorber layer of the device has to be doped with alkaline material. One possibility to incorporate alkaline material is a post deposition treatment (PDT), where a thin layer of NaF and/or KF is deposited onto the completely grown CIGS layer. In this paper we discuss the effects of PDT with different alkaline elements (Na and K) on the electronic properties of CIGS solar cells. We demonstrate that whereas Na is more effective in increasing the hole concentration in CIGS, K significantly improves the pn-junction quality. The beneficial role of K in improving the PV performance is attributed to reduced recombination at the CdS/CIGS interface, as revealed by temperature dependent J-V measurements, due to a stronger electronically inverted CIGS surface region. Computer simulations with the software SCAPS are used to verify this model. Furthermore, we show that PDT with either KF or NaF has also a distinct influence on other electronic properties of the device such as the position of the N1 signal in admittance spectroscopy and the roll-over of the J-V curve at low temperature. In view of the presented results we conclude that a model based on a secondary diode at the CIGS/Mo interface can best explain these features.

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Section: (Ii) Effect On Junction Propertiesmentioning

confidence: 99%

Unveiling the effects of post-deposition treatment with different alkaline elements on the electronic properties of CIGS thin film solar cells

Pianezzi

Reinhard

Chirilă

et al. 2014

Phys. Chem. Chem. Phys.

299

338

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“…Understanding the Cd diffusion mechanism and finding the optimal choice of the temperature treatments is of the utmost importance also for solar cells produced without a CdS buffer layer. For example, in cells produced by Cd implantation, the Cd diffusion is probably assisted by defects created by the implantation process and determines the final width of the inverted n -type layer …”

Section: Introductionmentioning

confidence: 99%

“…Upon elevated deposition temperatures the Cd dopant atoms are prone to diffuse into the underlying Cu-poor absorber material . Although such diffusion processes are highly relevant, and steer the performance of solar cells, there is only sparse data available regarding the diffusion mechanism of dopants and impurities. ,− …”

Section: Introductionmentioning

confidence: 99%

“…For example, in cells produced by Cd implantation, the Cd diffusion is probably assisted by defects created by the implantation process and determines the final width of the inverted n-type layer. 17 This has motivated us to investigate the diffusion of Cd impurities in Cu-poor CIS via theoretical calculations to widen our understanding on the diffusion process at the atomic scale, in particular in the Cu-poor region close to the interface with the buffer layer. Here we present a comprehensive large-scale ab initio study on the dynamics of Cd migration in bulk CuIn 5 Se 8 based on Car−Parrinello dynamics 20 aided by metadynamics.…”

Section: ■ Introductionmentioning

confidence: 99%

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Theoretical Study on the Diffusion Mechanism of Cd in the Cu-Poor Phase of CuInSe₂ Solar Cell Material

et al. 2013

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We have employed first-principles static and molecular dynamics (MD) calculations with semilocal and screened-exchange hybrid density functionals to study the diffusion of Cd in bulk CuIn 5 Se 8 , a copper-poor ordered vacancy compound of CuInSe 2 . The diffusion mechanism and the underlying kinetics/energetics were investigated by combining ab initio metadynamics simulations and nudged elastic band (NEB) calculations. We found that the migration of Cd occurs via a kick-out of Cu atoms, assisted by the pristine vacancies that are constitutive of this compound, and follows a double-hump energy profile. The rate-limiting step has a barrier of about 1 eV at 0 K but reduces to 0.3 eV at 850 K, pointing out non-negligible dynamical effects. Hybrid functional calculations reveal that Cd impurities are doubly positively charged (Cd 2+ ) in ptype and intrinsic conditions. The position of the 0/2+ charge transition level explains why Cd impurities do not constitute deep traps for carriers, making them not harmful for the solar cell device.

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“…Although there have been many attempts to eliminate buffer layers from the CIGS device structure so far, cell efficiencies demonstrated without buffer layers have remained low. For example, modification of the TCO layers using Zn(O,S):Al or ZnMgO:Al as alternatives to conventional ZnO:Al to tune the conduction band offset between the CIGS and TCO layers in a buffer-free configuration was attempted and cell efficiencies of 11.3% with Zn(O,S):Al and 7.96% with ZnMgO:Al were demonstrated. , As for CIGS surface modifications, ion implantation with elemental Cd or Zn has been reported to be effective in enhancing buffer-free cell efficiencies and 10.2% efficiency was demonstrated with Cd ion implantation . Post deposition treatments of the CIGS surface with elemental Zn has also been reported to be effective and a cell efficiency of 11.5% has been reported .…”

Section: Introductionmentioning

confidence: 99%

Si-Doping Effects in Cu(In,Ga)Se₂ Thin Films and Applications for Simplified Structure High-Efficiency Solar Cells

Ishizuka

Koida

Taguchi

et al. 2017

ACS Appl. Mater. Interfaces

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We found that elemental Si-doped Cu(In,Ga)Se (CIGS) polycrystalline thin films exhibit a distinctive morphology due to the formation of grain boundary layers several tens of nanometers thick. The use of Si-doped CIGS films as the photoabsorber layer in simplified structure buffer-free solar cell devices is found to be effective in enhancing energy conversion efficiency. The grain boundary layers formed in Si-doped CIGS films are expected to play an important role in passivating CIGS grain interfaces and improving carrier transport. The simplified structure solar cells, which nominally consist of only a CIGS photoabsorber layer and a front transparent and a back metal electrode layer, demonstrate practical application level solar cell efficiencies exceeding 15%. To date, the cell efficiencies demonstrated from this type of device have remained relatively low, with values of about 10%. Also, Si-doped CIGS solar cell devices exhibit similar properties to those of CIGS devices fabricated with post deposition alkali halide treatments such as KF or RbF, techniques known to boost CIGS device performance. The results obtained offer a new approach based on a new concept to control grain boundaries in polycrystalline CIGS and other polycrystalline chalcogenide materials for better device performance.

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Buffer-free Cu(In,Ga)Se2-solar cells by near-surface ion implantation

Cited by 6 publications

References 25 publications

Unveiling the effects of post-deposition treatment with different alkaline elements on the electronic properties of CIGS thin film solar cells

Unveiling the effects of post-deposition treatment with different alkaline elements on the electronic properties of CIGS thin film solar cells

Theoretical Study on the Diffusion Mechanism of Cd in the Cu-Poor Phase of CuInSe₂ Solar Cell Material

Si-Doping Effects in Cu(In,Ga)Se₂ Thin Films and Applications for Simplified Structure High-Efficiency Solar Cells

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Buffer-free Cu(In,Ga)Se2-solar cells by near-surface ion implantation

Cited by 6 publications

References 25 publications

Unveiling the effects of post-deposition treatment with different alkaline elements on the electronic properties of CIGS thin film solar cells

Unveiling the effects of post-deposition treatment with different alkaline elements on the electronic properties of CIGS thin film solar cells

Theoretical Study on the Diffusion Mechanism of Cd in the Cu-Poor Phase of CuInSe2 Solar Cell Material

Si-Doping Effects in Cu(In,Ga)Se2 Thin Films and Applications for Simplified Structure High-Efficiency Solar Cells

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Product

Resources

About

Theoretical Study on the Diffusion Mechanism of Cd in the Cu-Poor Phase of CuInSe₂ Solar Cell Material

Si-Doping Effects in Cu(In,Ga)Se₂ Thin Films and Applications for Simplified Structure High-Efficiency Solar Cells