Ghorbani, Elaheh ; Albe, Karsten (2018):
Influence of Cu and Na incorporation on the thermodynamic stability and electronic properties of β-In_2S_3.
In: Journal of Materials Chemistry C, 6 (27), pp. 7226-7231. Royal Society of Chemistry, ISSN 2050-7526,
DOI: 10.1039/c8tc01341a,
[Article]
Abstract
The aim of this study is to understand the effect of Na and Cu incorporation in In_2S_3, which is representing a Cd-free buffer system for chalcopyrite-type thin film solar cells based on Cu(In,Ga)Se_2 (CIGS). The formation energies and charge states of sodium and copper dopants in In_2S_3 are investigated by means of calculations based on electronic hybrid density functional theory using supercells of 320-atoms. Our results reveal a negative formation enthalpy of sodium in both In-rich and S-rich samples, which indicates the occurrence of side reactions and explains the existence of a chemically modified buffer layer in the presence of a Na-reservoir. Copper, in contrast, can be incorporated in large concentrations in In-rich In_2S_3 under n-type conditions, acting as an acceptor and thus limiting the n-type conductivity. For lower Fermi energies, however, reactions between Cu and the buffer material lead to the formation of Cu-containing secondary phases in the buffer side which is in qualitative agreement with experimental observations of Bär et al. [Bär et al., Appl. Mater. Interfaces, 2016, 8, 2120]. Sulfur rich samples are found to be more heavily doped under n-type conditions and we expect to have Na- and Cu-containing secondary phases formed under metal-poor growth conditions.
| Item Type: | Article |
|---|---|
| Erschienen: | 2018 |
| Creators: | Ghorbani, Elaheh ; Albe, Karsten |
| Title: | Influence of Cu and Na incorporation on the thermodynamic stability and electronic properties of β-In_2S_3 |
| Language: | English |
| Abstract: | The aim of this study is to understand the effect of Na and Cu incorporation in In_2S_3, which is representing a Cd-free buffer system for chalcopyrite-type thin film solar cells based on Cu(In,Ga)Se_2 (CIGS). The formation energies and charge states of sodium and copper dopants in In_2S_3 are investigated by means of calculations based on electronic hybrid density functional theory using supercells of 320-atoms. Our results reveal a negative formation enthalpy of sodium in both In-rich and S-rich samples, which indicates the occurrence of side reactions and explains the existence of a chemically modified buffer layer in the presence of a Na-reservoir. Copper, in contrast, can be incorporated in large concentrations in In-rich In_2S_3 under n-type conditions, acting as an acceptor and thus limiting the n-type conductivity. For lower Fermi energies, however, reactions between Cu and the buffer material lead to the formation of Cu-containing secondary phases in the buffer side which is in qualitative agreement with experimental observations of Bär et al. [Bär et al., Appl. Mater. Interfaces, 2016, 8, 2120]. Sulfur rich samples are found to be more heavily doped under n-type conditions and we expect to have Na- and Cu-containing secondary phases formed under metal-poor growth conditions. |
| Journal or Publication Title: | Journal of Materials Chemistry C |
| Journal volume: | 6 |
| Number: | 27 |
| Publisher: | Royal Society of Chemistry |
| Divisions: | 11 Department of Materials and Earth Sciences 11 Department of Materials and Earth Sciences > Material Science 11 Department of Materials and Earth Sciences > Material Science > Materials Modelling Zentrale Einrichtungen Zentrale Einrichtungen > University IT-Service and Computing Centre (HRZ) Zentrale Einrichtungen > University IT-Service and Computing Centre (HRZ) > Hochleistungsrechner |
| Date Deposited: | 24 Jul 2018 10:23 |
| DOI: | 10.1039/c8tc01341a |
| Official URL: | https://doi.org/10.1039/c8tc01341a |
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