金属氧化物多层膜晶体硅太阳电池的背场研究
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摘要
在n-Si与金属电极之间插入电子选择性材料Ca和Cs_2CO_3、LiF_x,可有效降低接触电阻和界面复合,该文研究Ca和Cs_2CO_3、LiF_x作为背场在氧化钨金属多层膜(WAW)/n-Si太阳电池中对电池性能和稳定性的影响。3种电子选择性材料中,2 nm的LiF_x对电池转换效率的提升最高,稳定性最好。对WAW/n-Si/LiF_x太阳电池R_s的各部分组成进行提取和分析,表明LiF_x/n-Si的接触电阻和LiF_x/Ag接触电阻仅占总串联电阻的0.2%,背场工艺得到最佳的优化。将LiF_x做为背场应用于氧化钒金属多层膜背接触晶体硅(MLBC)太阳电池中,达到19.02%的转换效率,而且用环氧树脂封装的MLBC太阳电池放置在空气中表现出极好的稳定性。
In this work,the back surface field of the WAW/n-Si solar cells was optimized by introducing electronselective interfacial layers Ca,Cs_2 CO_3 and LiF_xto isolate n-Si from metal electrode. The interfacial layers can not only reduce the Schottky barrier formed by n-Si/Ag contact dramatically,but also passivate the hetero-contact,resulting in negligible contact resistivity and low surface recombination velocity. By incorporating 2 nm LiF_x as the back surfacefield,the WAW/n-Si solar cells demonstrated the best performance and stability. The components of the WAW/n-Si/LiF_x solar cell were extracted and analyzed,indicating that the contact resistance of LiF_x/n-Si and LiF_x/Ag comprised only 0.2% of the total series resistance and the back surface field was optimized. Applying the optimized LiFxas the BSF,an efficiency of 19.02% was achieved for the MLBC solar cell. Furthermore,the MLBC solar cells were encapsulated by epoxy resin and showed high stability when stored in ambient.
In this work,the back surface field of the WAW/n-Si solar cells was optimized by introducing electronselective interfacial layers Ca,Cs_2 CO_3 and LiF_xto isolate n-Si from metal electrode. The interfacial layers can not only reduce the Schottky barrier formed by n-Si/Ag contact dramatically,but also passivate the hetero-contact,resulting in negligible contact resistivity and low surface recombination velocity. By incorporating 2 nm LiF_x as the back surfacefield,the WAW/n-Si solar cells demonstrated the best performance and stability. The components of the WAW/n-Si/LiF_x solar cell were extracted and analyzed,indicating that the contact resistance of LiF_x/n-Si and LiF_x/Ag comprised only 0.2% of the total series resistance and the back surface field was optimized. Applying the optimized LiFxas the BSF,an efficiency of 19.02% was achieved for the MLBC solar cell. Furthermore,the MLBC solar cells were encapsulated by epoxy resin and showed high stability when stored in ambient.
引文
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[19] Hsu Feng-Hao,Wang Na-Fu,Tsai Yu-Zeu,et al.Enhanced carrier collection in p-Ni1-xO:Li/n-Siheterojunction solar cells using LiF/Al electrodes[J].Thin Solid Films,2014,573:159—163.
[2] Bao Jie,Wu Weiliang,Liu Zongtao,et al. Siliconbased solar cells using a multilayer oxide as emitter[J].AIP Advances,2016,6(8):085304.
[3] Wu Wweiliang,Lin Wenjie,Bao Jie,et al. Dopant-freemultilayer back contact silicon solar cells employingV2Ox/metal/V2Oxas an emitter[J]. RSC Advances,2017,7(38):23851—23858.
[4] Li Shenhao, Yao Zhirong, Zhou Jixiang, et al.Fabrication and characterization of WO3thin films onsilicon surface by thermal evaporation[J]. MaterialsLetters,2017,195:213—216.
[5] Almora O, Gerling L G, Voz C, et al. Superiorperformance of V2O5as hole selective contact over othertransition metal oxides in silicon heterojunction solarcells[J]. Solar Energy Materials and Solar Cells,2017,168:221—226.
[6] Wu Weiliang,Bao Jie,Jia Xuguang,et al. Dopant-freeback contact silicon heterojunction solar cells employingtransition metal oxide emitters[J]. Physica Status Solidi(RRL)-Rapid Research Letters,2016,10(9):662—667.
[7] Geissbühler J,Werner J,de Nicolas S M,et al. 22.5%efficient silicon heterojunction solar cell withmolybdenum oxide hole collector[J]. Applied PhysicsLetters,2015,107(8):081601.
[8] Gerling L G,Voz C,Alcubilla R,et al. Origin ofpassivation in hole-selective transition metal oxides forcrystalline silicon heterojunction solar cells[J]. Journalof Materials Research,2016,32(2):260—268.
[9] MasmitjàG,Gerling L G,Ortega P,et al. V2Ox-basedhole-selective contacts for c-Si interdigitated back-contacted solar cells[J]. Journal of Materials ChemistryA,2017,5(19):9182—9189.
[10] Bullock J,Zheng P,Jeangros Q,et al. Lithium fluoridebased electron contacts for high efficiency n-typecrystalline silicon solar cells[J]. Advanced EnergyMaterials,2016,6(14):1600241.
[11] Wan Yimao, Samundsett C, Bullock J, et al.Conductive and stable magnesium oxide electron-selective contacts for efficient silicon solar cells[J].Advanced Energy Materials,2017,7(5):1601863.
[12] Schroder D K,Meier D L. Solar cell contact resistance—A review[J]. IEEE Transactions on Electron Devices,1984,31(5):637—647.
[13] Allen T G,Bullock J,Zheng P,et al. Calcium contactsto n-type crystalline silicon solar cells[J]. Progress inPhotovoltaics:Research and Applications,2017,25(7):636—644.
[14] Wan Yimao,Samundsett C,Yan D,et al. A magnesium/amorphous silicon passivating contact for n-typecrystalline silicon solar cells[J]. Applied PhysicsLetters,2016,109(11):113901.
[15] Zhang Yunfang,Cui Wei,Zhu Yawen,et al. Highefficiency hybrid PEDOT:PSS/nanostructured siliconSchottky junction solar cells by doping-free rear contact[J]. Energy&Environmental Science,2015,8(1):297—302.
[16] Wan Yimao, Samundsett C, Bullock J, et al.Magnesium fluoride electron-selective contacts forcrystalline silicon solar cells[J]. ACS AppliedMaterials&Interfaces,2016,8(23):14671—14677.
[17] Morato A,Vermang B,Goverde H,et al. Electricalcharacterization of ALD Al2O3-HfO2and PECVD Al2O3passivation layers for p-type CZ-Silicon PERC solar cells[A]. proceedings of the Photovoltaic SpecialistsConference[C],Austin,TX,USA,2012.
[18] Yang Xinbo,Bi Qunyu,Ali H,et al. High-performanceTiO2-based electron-selective contacts for crystallinesilicon solar cells[J]. Advanced Materials,2016,28(28):5891.
[19] Hsu Feng-Hao,Wang Na-Fu,Tsai Yu-Zeu,et al.Enhanced carrier collection in p-Ni1-xO:Li/n-Siheterojunction solar cells using LiF/Al electrodes[J].Thin Solid Films,2014,573:159—163.