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Title:
 
Recombination in the Depletion Region of Actual Si Solar Cells
 
Author(s):
 
L. Abenante, M. Tucci
 
Keywords:
 
Recombination, Modelling / Modeling
 
Topic:
 
Advanced Photovoltaics : New Concepts and Ultra-High Efficiency
Subtopic: Fundamental Studies
Event: 26th European Photovoltaic Solar Energy Conference and Exhibition
Session: 1CV.3.18
 
Pages:
 
285 - 289
ISBN: 3-936338-27-2
Paper DOI: 10.4229/26thEUPVSEC2011-1CV.3.18
 
Price:
 
 
0,00 EUR
 
Document(s): paper
 

Abstract/Summary:


Expressing the SRH-recombination rate, U, in the volume of a p-n junction depletion region (JDR) according to Sah, Noyce, Shockley (SNS) and Choo allows deriving a new expression for recombination current density, J2, that is a function of the recombination velocity, S2, at a surface, which is located in a narrow region around the position of the maximum U-value. The value of ideality factor n2, in both the expression for U and new expression for J2, is not fixed. Measured dark and light J-V curves of four Si solar cells are fitted by adjusting n2 and cell resistances in the double exponential model for direct current density at values that do not vary with applied bias. The saturation current density, J1, is calculated at n1=1. J2 is calculated by both integrating U over the JDR and using the new expression. The values for transport parameters are previously extracted from measured quantum efficiency. In two devices, the integral of U is capable of giving the fit-values of J2. In these cells, the new expression is evaluated at the fit-value for J2 resulting in very low S2-values. In the remaining cells, the integral of U gives unfit J2-values at any n2-value. In these devices, the fit-values of J2 are obtained with the new expression at assigned values for S2. Consistent with the literature, the fit-values of n2 vary from 1.7 to 3.9. In the cells, where it cannot be calculated with the integral of U, the maximum S2 is 976 cm/s at n2=3.9. In these cases, J2 appears to be determined by surfaces that are much more recombining than the p-n junction interface.