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Measurement of Relaxation Time of Excess Carriers in Si and CIGS Solar Cells by Modulated Electroluminescence Technique
Author(s) -
Khatavkar Sanchit,
Muniappan Kulasekaran,
Kannan Chinna V.,
Kumar Vijay,
Narsimhan Krishnamachari L.,
Nair Pradeep R.,
Vasi Juzer M.,
Contreras Miguel A.,
van Hest Maikel F. A. M.,
Arora Brij M.
Publication year - 2018
Publication title -
physica status solidi (a)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.532
H-Index - 104
eISSN - 1862-6319
pISSN - 1862-6300
DOI - 10.1002/pssa.201700267
Subject(s) - electroluminescence , relaxation (psychology) , copper indium gallium selenide solar cells , optoelectronics , materials science , carrier lifetime , trapping , solar cell , silicon , nanotechnology , psychology , social psychology , ecology , layer (electronics) , biology
Excess carrier lifetime plays a crucial role in determining the efficiency of solar cells. In this paper, we use the frequency dependence of inphase and quadrature components of modulated electroluminescence (MEL) to measure the relaxation time (decay) of excess carriers. The advantage of the MEL technique is that the relaxation time is obtained directly from the angular frequency at which the quadrature component peaks. It does not need knowledge of the material parameters like mobility, etc., and can be used for any finished solar cells which have detectable light emission. The experiment is easy to perform with standard electrical equipment. For silicon solar cells, the relaxation time is dominated by recombination and hence, the relaxation time is indeed the excess carrier lifetime. In contrast, for the CIGS solar cells investigated here, the relaxation time is dominated by trapping and emission from shallow minority carrier traps.