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Rear‐Passivated Ultrathin Cu(In,Ga)Se 2 Films by Al 2 O 3 Nanostructures Using Glancing Angle Deposition Toward Photovoltaic Devices with Enhanced Efficiency
Author(s) -
Chen ChiaWei,
Tsai HungWei,
Wang YiChung,
Shih YuChuan,
Su TengYu,
Yang ChenHua,
Lin WeiSheng,
Shen ChangHong,
Shieh JiaMing,
Chueh YuLun
Publication year - 2019
Publication title -
advanced functional materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.069
H-Index - 322
eISSN - 1616-3028
pISSN - 1616-301X
DOI - 10.1002/adfm.201905040
Subject(s) - materials science , passivation , nanostructure , energy conversion efficiency , metal , solar cell , nanotechnology , surface roughness , chemical engineering , deposition (geology) , oxide , atomic layer deposition , aluminium , analytical chemistry (journal) , optoelectronics , thin film , layer (electronics) , metallurgy , composite material , paleontology , sediment , biology , chemistry , chromatography , engineering
In this work, for the first time, the addition of aluminum oxide nanostructures (Al 2 O 3 NSs) grown by glancing angle deposition (GLAD) is investigated on an ultrathin Cu(In,Ga)Se 2 device (400 nm) fabricated using a sequential process, i.e., post‐selenization of the metallic precursor layer. The most striking observation to emerge from this study is the alleviation of phase separation after adding the Al 2 O 3 NSs with improved Se diffusion into the non‐uniformed metallic precursor due to the surface roughness resulting from the Al 2 O 3 NSs. In addition, the raised Na concentration at the rear surface can be attributed to the increased diffusion of Na ion facilitated by Al 2 O 3 NSs. The coverage and thickness of the Al 2 O 3 NSs significantly affects the cell performance because of an increase in shunt resistance associated with the formation of Na 2 Se X and phase separation. The passivation effect attributed to the Al 2 O 3 NSs is well studied using the bias‐EQE measurement and J–V characteristics under dark and illuminated conditions. With the optimization of the Al 2 O 3 NSs, the remarkable enhancement in the cell performance occurs, exhibiting a power conversion efficiency increase from 2.83% to 5.33%, demonstrating a promising method for improving ultrathin Cu(In,Ga)Se 2 devices, and providing significant opportunities for further applications.