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Role of oxygen and chlorine impurities in β−In2S3 : A first-principles study

Ghorbani, Elaheh and Albe, Karsten (2018):
Role of oxygen and chlorine impurities in β−In2S3 : A first-principles study.
In: Physical Review B, pp. 205201(1-8), 98, (20), ISSN 2469-9950, DOI: 10.1103/PhysRevB.98.205201, [Online-Edition: https://doi.org/10.1103/PhysRevB.98.205201],
[Article]

Abstract

For environmental reasons there is a need for alternative Cd-free buffer materials in Cu(In,Ga)(S,Se_2 (CIGSSe) based thin film solar cells. In this context, β−In_2S_3 is one candidate material, whose optoelectronic properties can be affected by the presence of impurities. In this study, we investigate the impact of O and Cl impurities on the electronic and optical behavior of β−In_2S_3 by means of electronic structure calculations within density functional theory using hybrid functionals. We find that β−In_2S_3 is thermodynamically stable being in contact with both O and Cl reservoirs. Furthermore, we present evidence that O on interstitial sites (O_i) and Cl on 8c In sites (Cl_In) cause low-temperature persistent electron photoconductivity. At room temperature, defect levels associated with Cl on S sites (Cl_S, Cl_S′, and Cl_S'') get thermally ionized and release free electrons into the system. Thus, the n-type conductivity of the In_2S_3 buffer layer increases. O impurities on S sites, in contrast, are electrically inert. Hence, we conclude that intentional doping by Cl is a means to improve the properties of β−In_2S_3 serving as buffer material.

Item Type: Article
Erschienen: 2018
Creators: Ghorbani, Elaheh and Albe, Karsten
Title: Role of oxygen and chlorine impurities in β−In2S3 : A first-principles study
Language: English
Abstract:

For environmental reasons there is a need for alternative Cd-free buffer materials in Cu(In,Ga)(S,Se_2 (CIGSSe) based thin film solar cells. In this context, β−In_2S_3 is one candidate material, whose optoelectronic properties can be affected by the presence of impurities. In this study, we investigate the impact of O and Cl impurities on the electronic and optical behavior of β−In_2S_3 by means of electronic structure calculations within density functional theory using hybrid functionals. We find that β−In_2S_3 is thermodynamically stable being in contact with both O and Cl reservoirs. Furthermore, we present evidence that O on interstitial sites (O_i) and Cl on 8c In sites (Cl_In) cause low-temperature persistent electron photoconductivity. At room temperature, defect levels associated with Cl on S sites (Cl_S, Cl_S′, and Cl_S'') get thermally ionized and release free electrons into the system. Thus, the n-type conductivity of the In_2S_3 buffer layer increases. O impurities on S sites, in contrast, are electrically inert. Hence, we conclude that intentional doping by Cl is a means to improve the properties of β−In_2S_3 serving as buffer material.

Journal or Publication Title: Physical Review B
Volume: 98
Number: 20
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: 06 Nov 2018 11:27
DOI: 10.1103/PhysRevB.98.205201
Official URL: https://doi.org/10.1103/PhysRevB.98.205201
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