Thermodynamic stability, phase separation and Ag grading in (Ag,Cu)(In,Ga)Se<sub>2</sub> solar absorbers

Sopiha, Kostiantyn V.; Larsen, Jes K.; Donzel‐Gargand, Olivier; Khavari, Faraz; Keller, Jan; Edoff, Marika; Platzer‐Björkman, Charlotte; Persson, Clas; Scragg, Jonathan J.

doi:10.1039/d0ta00363h

Cited by 34 publications

(41 citation statements)

References 51 publications

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“…This is in agreement with the conventional belief on detrimental impact of increased temperature on the efficiency of solar cells. However, the impact of this temperature is not as reported in many other literature [21,22]. The J-V curves obtained from the coupled simulation is in agreement with the experimental data reported in Fig.…”

Section: Temperature Impact On J-v Characteristicssupporting

confidence: 89%

Simulation of Heat Loss in CZTSSe Thin Film Solar Cells: A Coupled Optical-Electrical-Thermal Modeling

Zandi

Seresht

Gorji

2021

Preprint

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A coupled optical-electrical-thermal modeling has been developed to investigate the heat generation in CZTSSe solar cells via Thermalization, Joule heat, Peltier heat, Surface Recombination heat, and non-radiative recombination heat and also the heat dissipation via convective and radiative cooling. These were calculated and displayed in 2D and 3D maps either at zero bias or open-circuit voltage (V oc) conditions. At V=0, the heat is generated mainly at the junction of CZTSSe/CdS where the thermalization and Joule heats are dominantly higher compared to non-radiative (SRH and Auger) recombination heat. However, at V=V oc , the nan-radiative recombination heat becomes comparatively higher than the Joule heating whereas the thermalization remains highest as before. Apart from the bulk heating factors, we also studied the surface recombination and Peltier heat generation. The surface recombination heat is higher at V=V oc compared to at V=0 while the Peltier heat is zero at V=V oc which can be explained by looking at the energy band diagrams at these voltages. The total heat generation does not change much across the cell thickness (<5×10 9 W/m 3) as the cell is quite thin. Nevertheless, the individual impact of every heat generation factor on power-density and current-voltage characteristics of the cell reveals that the thermalization, Joule, and non-radiative recombination heats reduce the open-circuit voltage of the cell from 0.54 V to 0.49 V (∆V = 0.047 V) while the Peltier and surface recombination heat is less effective. The temperature of the cell shows a small distribution across the cell (0.01 K). However, the temperature of the initial study at 293 K increases to 315-320 K for the coupled study. At this increased temperature, the short current-density doesn’t change but the fill factor decreases from 73.8% to 71.8% and, therefore, the energy conversion efficiency of the cell falls by 11.11% (from initial 12.78% to 11.36%). All the total heat dissipation, convective, and radiation cooling follow a similar trend to the total heat generation but convective cooling is the dominant component of dissipation.

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Section: Temperature Impact On J-v Characteristicssupporting

confidence: 89%

Simulation of Heat Loss in CZTSSe Thin Film Solar Cells: A Coupled Optical-Electrical-Thermal Modeling

Zandi

Seresht

Gorji

2021

Preprint

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“…[ 29 ] Other example of such methodology applied to solar absorber alloys can be found in our earlier works. [ 30,31 ] The Brillouin‐zone integrations were performed using 3 × 2 × 2 Γ ‐centered Monkhorst–Pack grid [ 32 ] and a cutoff energy of 350 eV. The ionic force threshold for atomic relaxations was set to 0.01 eV Å −1 .…”

Section: Methodsmentioning

confidence: 99%

Comparison of Sulfur Incorporation into CuInSe₂ and CuGaSe₂ Thin‐Film Solar Absorbers

Khavari

Keller

Larsen

et al. 2020

Physica Status Solidi (a)

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“…[2] In addition, a miscibility gap was predicted for high Ag and intermediate Ga contents. [23] The present contribution first reinvestigates the solar cell performance of the samples with a CdS buffer from our previous work [2] after %8 months of air exposure ("office storage") and links the observed differences in long-term stability to the formation of OVCs. In the second and third part of the article, the effect of a varied off-stoichiometry and the corresponding tendency to OVC formation are investigated for samples with a constant absorber composition of [Ag]/[I] ¼ 0.8 and [Ga]/[III] ¼ 0.85 (i.e., same as in the previous study [2] ).…”

Section: Introductionmentioning

confidence: 95%

On the Paramount Role of Absorber Stoichiometry in (Ag,Cu)(In,Ga)Se₂ Wide‐Gap Solar Cells

et al. 2020

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This contribution evaluates the effect of absorber off‐stoichiometry in wide‐gap (Ag,Cu)(In,Ga)Se2 (ACIGS) solar cells. It is found that ACIGS films show an increased tendency to form ordered vacancy compounds (OVCs) with increasing Ga and Ag contents. Very little tolerance to off‐stoichiometry is detected for absorber compositions giving the desired properties of 1) an optimum bandgap (EG) for a top cell in tandem devices (EG = 1.6–1.7 eV) and at the same time 2) a favorable band alignment with a CdS buffer layer. Herein, massive formation of either In‐ or Ga‐enriched OVC patches is found for group I‐poor ACIGS. As a consequence, carrier transport and charge collection are significantly impeded in corresponding solar cells. The transport barrier appears to be increasing with storage time, questioning the long‐term stability of wide‐gap ACIGS solar cells. Furthermore, the efficiency of samples with very high Ga and Ag contents depends on the voltage sweep direction. It is proposed that the hysteresis behavior is caused by a redistribution of mobile Na ions in the 1:1:2 absorber lattice upon voltage bias. Finally, a broader perspective on OVC formation in the ACIGS system is provided and fundamental limitations for wide‐gap ACIGS solar cells are discussed.

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Thermodynamic stability, phase separation and Ag grading in (Ag,Cu)(In,Ga)Se₂ solar absorbers

Abstract: Herein, we prove that (Ag,Cu)(In,Ga)Se2 alloy system has a wide miscibility gap, which can induce compositional grading and cause phase separation in thin-film solar absorbers.

Cited by 34 publications

References 51 publications

Simulation of Heat Loss in CZTSSe Thin Film Solar Cells: A Coupled Optical-Electrical-Thermal Modeling

Simulation of Heat Loss in CZTSSe Thin Film Solar Cells: A Coupled Optical-Electrical-Thermal Modeling

Comparison of Sulfur Incorporation into CuInSe₂ and CuGaSe₂ Thin‐Film Solar Absorbers

On the Paramount Role of Absorber Stoichiometry in (Ag,Cu)(In,Ga)Se₂ Wide‐Gap Solar Cells

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Thermodynamic stability, phase separation and Ag grading in (Ag,Cu)(In,Ga)Se2 solar absorbers

Abstract: Herein, we prove that (Ag,Cu)(In,Ga)Se2 alloy system has a wide miscibility gap, which can induce compositional grading and cause phase separation in thin-film solar absorbers.

Cited by 34 publications

References 51 publications

Simulation of Heat Loss in CZTSSe Thin Film Solar Cells: A Coupled Optical-Electrical-Thermal Modeling

Simulation of Heat Loss in CZTSSe Thin Film Solar Cells: A Coupled Optical-Electrical-Thermal Modeling

Comparison of Sulfur Incorporation into CuInSe2 and CuGaSe2 Thin‐Film Solar Absorbers

On the Paramount Role of Absorber Stoichiometry in (Ag,Cu)(In,Ga)Se2 Wide‐Gap Solar Cells

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Thermodynamic stability, phase separation and Ag grading in (Ag,Cu)(In,Ga)Se₂ solar absorbers

Comparison of Sulfur Incorporation into CuInSe₂ and CuGaSe₂ Thin‐Film Solar Absorbers

On the Paramount Role of Absorber Stoichiometry in (Ag,Cu)(In,Ga)Se₂ Wide‐Gap Solar Cells