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Development of high‐efficiency large‐area screen‐printed solar cells on direct kerfless epitaxially grown monocrystalline Si wafer and structure
Author(s) -
Chen ChiaWei,
Hao Ruiying,
Upadhyaya Vijaykumar D.,
Ravi T. S.,
Rohatgi Ajeet
Publication year - 2016
Publication title -
progress in photovoltaics: research and applications
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.286
H-Index - 131
eISSN - 1099-159X
pISSN - 1062-7995
DOI - 10.1002/pip.2779
Subject(s) - wafer , materials science , epitaxy , common emitter , optoelectronics , monocrystalline silicon , passivation , doping , substrate (aquarium) , layer (electronics) , solar cell , nanotechnology , silicon , oceanography , geology
This paper demonstrates the potential of epitaxially grown Si wafers with doped layers for high‐efficiency solar cells. Boron‐doped 239 cm 2 180–200 µm thick 2 Ω‐cm wafers were grown with and without 15 µm thick p + layer, with a doping in the range of 10 17 ~10 18 cm −3 . A layer transfer process involving porous Si layer to lift off epi‐Si wafers from the reusable substrate was used. The pp + wafers were converted into n + pp + passivated emitter rear totally diffused (PERT) cells by forming an oxide‐passivated POCl 3 ‐diffused n + emitter at the front, and oxide/nitride‐passivated epitaxially grown p + BSF at the entire back, with local screen‐printed contacts. To demonstrate and quantify the benefit of the epi‐grown p + layer, standard passivated emitter and rear cells (PERCs) with local BSF and contacts were also fabricated on p‐type epi‐Si wafers as well on commercial‐grade Cz wafers. Sentaurus 2D device model was used to assess the impact of the epi‐grown p + layer, which showed an efficiency gain of ~0.5% for this PERT structure over the traditional PERC. This was validated by the cell results, which showed an efficiency of ~20.1% for the PERC, and ~20.3% for the PERT cell using epi‐Si wafers. Experimental data showed higher FF in PERT cells, largely because of the decrease in lateral resistance on the rear side. Efficiency gain, a result of higher FF , was greater than the recombination loss in the p + layer because of the lightly doped thick p + epi‐grown region used in this study. Copyright © 2016 John Wiley & Sons, Ltd.