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Title: Measurement of Relaxation Time of Excess Carriers in Si and CIGS Solar Cells by Modulated Electroluminescence Technique

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.
 [1] ;  [1] ;  [2] ;  [2] ;  [1] ;  [1] ;  [1] ;  [3] ;  [1]
  1. Indian Inst. of Technology (IIT), Mumbai (India)
  2. MoserBaer Photovoltaic Pvt. Ltd., Greater Noida (India)
  3. National Renewable Energy Lab. (NREL), Golden, CO (United States)
Publication Date:
Report Number(s):
Journal ID: ISSN 1862-6300
Grant/Contract Number:
Accepted Manuscript
Journal Name:
Physica Status Solidi. A, Applications and Materials Science
Additional Journal Information:
Journal Volume: 215; Journal Issue: 2; Journal ID: ISSN 1862-6300
Research Org:
National Renewable Energy Lab. (NREL), Golden, CO (United States)
Sponsoring Org:
USDOE Office of Energy Efficiency and Renewable Energy (EERE)
Country of Publication:
United States
14 SOLAR ENERGY; 36 MATERIALS SCIENCE; CIGS solar cells; frequency dependence; modulated electroluminescence; relaxation time; Si-HJ solar cells
OSTI Identifier:
Alternate Identifier(s):
OSTI ID: 1408251