钾掺杂对柔性CZTSSe薄膜及其太阳电池性能的影响
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摘要
本文采用磁控溅射加后续硒化的方法制备柔性CZTSSe薄膜,通过向硒化气氛中引入钾元素实现了钾的有效掺杂。研究了钾掺杂量对柔性CZTSSe薄膜和电池性能的影响。X射线衍射和Raman结果表明适量掺入钾元素可以显著提高CZTSSe薄膜的(112)择优取向,增大晶粒尺寸,但钾元素掺杂量过高时又会使晶粒尺寸变小降低薄膜结晶性。另外钾元素的掺入也会改变CZTSSe/Cd S间能带匹配情况,少量的钾元素掺杂对CZTSSe/Cd S间导带失调值(CBO)影响不大,过量掺入钾元素则会明显增大CZTSSe/Cd S间的CBO绝对值,进而降低柔性CZTSSe太阳电池转换效率。发现钾元素掺杂量为1. 0μmol时,所制备的柔性CZTSSe薄膜平均晶粒尺寸超过1μm,且具有很强的(112)择优取向;制作的CZTSSe/Cd S具有最佳的CBO数值,相应柔性太阳电池的最高值转换效率为3. 06%。
Flexible K-doped CZTSSe thin films were synthesized by selenizing the magnetron co-sputtered precursors. The influence of the K-content on the microstructures,energy band structures of the thin film and performance of the solar-cells was investigated with X-ray diffraction,X-ray photoelectron spectroscopy,scanning electron microscopy and Raman spectroscopy. The preliminary results show that the K-content had a major impact. For example,as the K-content increased,< 112 > preferentially-oriented growth became increasingly obvious,the grain-size changed in an increase-decrease mode; the over amount K-induced conduction band offset( CBO) increased and the CBO absolute-value at CZTSSe/CdS interface increased because K-doping induced band structure re-alignment,resulting in efficiency deterioration of solar-cell. With K-content of 1. 0 μmol,the < 112 > preferentially grown CZTSSe thin film had average grain-size of 1 μm and optimal CBO at CZTSSe/CdS interface. Moreover,the highest efficiency of the K-doped flexible solar-cell reached 3. 06%.
Flexible K-doped CZTSSe thin films were synthesized by selenizing the magnetron co-sputtered precursors. The influence of the K-content on the microstructures,energy band structures of the thin film and performance of the solar-cells was investigated with X-ray diffraction,X-ray photoelectron spectroscopy,scanning electron microscopy and Raman spectroscopy. The preliminary results show that the K-content had a major impact. For example,as the K-content increased,< 112 > preferentially-oriented growth became increasingly obvious,the grain-size changed in an increase-decrease mode; the over amount K-induced conduction band offset( CBO) increased and the CBO absolute-value at CZTSSe/CdS interface increased because K-doping induced band structure re-alignment,resulting in efficiency deterioration of solar-cell. With K-content of 1. 0 μmol,the < 112 > preferentially grown CZTSSe thin film had average grain-size of 1 μm and optimal CBO at CZTSSe/CdS interface. Moreover,the highest efficiency of the K-doped flexible solar-cell reached 3. 06%.
引文
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[13] Gao J,Li M,Xu J,et al. Development of Sol-Gel Fabrication of Cu2Zn Sn S4Thin-Films and Solar Cells[J]. Materials Review,2017,31(17):146-151
[14] Ya Li J,Du Q,Liu W,et al. The Band Offset at Cd S/Cu2Zn Sn S4,Heterojunction Interface[J]. Electronic Materials Letters,2012,8(4):365-367
[15] Johnson M,Baryshev S V,Thimsen E,et al. Alkali-Metal-Enhanced Grain Growth in Cu2Zn Sn S4Thin Films[J]. Energy&Environmental Science,2014,7(6):1931
[16] Yan C,Liu F,Song N,et al. Band Alignments of Different Buffer Layers(Cd S,Zn(O,S),and In2S3)on Cu2Zn Sn S4[J]. Applied Physics Letters,2014,104(17):173901
[17] Haight R,Barkhouse A,Gunawan O,et al. Band alignment at the Cu2Zn Sn(SxSe1-x)4/Cd S Interface[J]. Applied Physics Letters,2011,98(25):253502
[2] Kim J,Hiroi H,Todorov T K,et al. High Efficiency Cu2Zn Sn(S,Se)4Solar Cells by Applying a Double In2S3/Cd S Emitter[J]. Advanced Materials,2014,26(44):7427-7431
[3] López-Marino S,Sánchez Y,Espíndola-Rodríguez M,et al. Alkali Doping Strategies for Flexible and Light-Weight Cu2Zn Sn Se4Solar Cells[J]. Journal of Materials Chemistry,2016,A4(5):1895-1907
[4] Li J,Shen H,Shang H,et al. Performance Improvement of Flexible CZTSSe Thin Film Solar Cell by Adding a Ge Buffer Layer[J]. Materials Letters,2017,190:188-190
[5] Dong L,Cheng S,Lai Y,et al. Sol-Gel Processed CZTS Thin Film Solar Cell on Flexible Molybdenum Foil[J].Thin Solid Films,2017,626:168-172
[6]张力,何青,徐传明,等.金属Cr阻挡层对柔性不锈钢衬底Cu(In,Ga)Se2太阳电池性能的影响[J].半导体学报,2006,10:1781-1784
[7] Sun K,Liu F,Yan C,et al. Influence of Sodium Incorporation on Kesterite Cu2Zn Sn S4,Solar Cells Fabricated on Stainless Steel Substrates[J]. Solar Energy Materials&Solar Cells,2016,157:565-571
[8] Boscher N,Carmalt C,Parkin I. Atmospheric Pressure CVD of Ti Se2Thin Films on Glass[J]. Chemical Vapor Deposition,2010,12(1):54-58
[9] Tong Z,Yan C,Su Z,et al. Effects of Potassium Doping on Solution Processed Kesterite Cu2Zn Sn S4Thin Film Solar Cells[J]. Applied Physics Letters,2014,105(22):7426.
[10] Hsieh Y,Han Q,Jiang C,et al. Efficiency Enhancement of Cu2Zn Sn(S,Se)4Solar Cells via Alkali Metals Doping[J]. Advanced Energy Materials,2016,6(7):1502386
[11] Wang W,Shen H,Yao H,et al. Effect of Sulfurization Temperature on the Property of Cu2Zn Sn S4Thin Film by Eco-Friendly Nanoparticle Ink Method[J]. Applied Physics,2017,A123(9):599
[12] Li J,Shen H,Wang W,et al. Improvement of CZTSSe Thin Film Solar Cell by Introducing a Three-Layer Structure Precursor[J]. Materials Letters,2016,172:90-93
[13] Gao J,Li M,Xu J,et al. Development of Sol-Gel Fabrication of Cu2Zn Sn S4Thin-Films and Solar Cells[J]. Materials Review,2017,31(17):146-151
[14] Ya Li J,Du Q,Liu W,et al. The Band Offset at Cd S/Cu2Zn Sn S4,Heterojunction Interface[J]. Electronic Materials Letters,2012,8(4):365-367
[15] Johnson M,Baryshev S V,Thimsen E,et al. Alkali-Metal-Enhanced Grain Growth in Cu2Zn Sn S4Thin Films[J]. Energy&Environmental Science,2014,7(6):1931
[16] Yan C,Liu F,Song N,et al. Band Alignments of Different Buffer Layers(Cd S,Zn(O,S),and In2S3)on Cu2Zn Sn S4[J]. Applied Physics Letters,2014,104(17):173901
[17] Haight R,Barkhouse A,Gunawan O,et al. Band alignment at the Cu2Zn Sn(SxSe1-x)4/Cd S Interface[J]. Applied Physics Letters,2011,98(25):253502