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Enhanced lateral current transport via the front N + diffused layer of n‐type high‐efficiency back‐junction back‐contact silicon solar cells
Author(s) -
Granek Filip,
Hermle Martin,
Huljić Dominik M.,
SchultzWittmann Oliver,
Glunz Stefan W.
Publication year - 2009
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.862
Subject(s) - sheet resistance , materials science , equivalent series resistance , doping , electrical resistivity and conductivity , solar cell , current density , optoelectronics , contact resistance , layer (electronics) , composite material , electrical engineering , voltage , physics , engineering , quantum mechanics
N‐type back‐contact back‐junction solar cells were processed with the use of industrially relevant structuring technologies such as screen‐printing and laser processing. Application of the low‐cost structuring technologies in the processing of the high‐efficiency back‐contact back‐junction silicon solar cells results in a drastic increase of the pitch on the rear cell side. The pitch in the range of millimetres leads to a significant increase of the lateral base resistance. The application of a phosphorus doped front surface field (FSF) significantly reduces the lateral base resistance losses. This additional function of the phosphorus doped FSF in reducing the lateral resistance losses was investigated experimentally and by two‐dimensional device simulations. Enhanced lateral majority carrier's current transport in the front n + diffused layer is a function of the pitch and the base resistivity. Experimental data show that the application of a FSF reduces the total series resistance of the measured cells with 3.5 mm pitch by 0.1 Ω cm 2 for the 1 Ω cm base resistivity and 1.3 Ω cm 2 for the 8 Ω cm base resistivity. Two‐dimensional simulations of the electron current transport show that the electron current density in the front n + diffused layer is around two orders of magnitude higher than in the base of the solar cell. The best efficiency of 21.3% was obtained for the solar cell with a 1 Ω cm specific base resistivity and a front surface field with sheet resistance of 148 Ω/sq. Copyright © 2008 John Wiley & Sons, Ltd.