Photoluminescence as a diagnostic of semiconductors

Distributed series resistance effects in solar cells are analyzed and the correctness of representing these by a lumped parameter is discussed for any conditions of bias and illumination In addition to a general mathematical methodology, analytical expressions are derived to simplify the estimation of series resistance effects on the dark and illuminated J-V characteristics of the cell The equivalent series resistance (r s ) in the dark is found to decrease with current density J from r_{b} + r_{e}/3 at small J to ( r_{e} r_{b})^{1/2} at very high J , where r e and r b are the emitter layer and base region resistances, respectively For illuminated conditions r s depends on J as well, being maximum near short-circuit and minimum near open-circuit; however, r s further depends on the photogenerated current J L : its short-circuit value increases with J L from r_{b} + r_{e}/3 to r_{b} + r_{e}/2 and the open-circuit value decreases with J L from r_{b} + r_{e}/3 to (r_{e}r_{b})^{1/2}  The variability of r s is therefore related to the relative importance of r b and r_{e};r_{b} plays the role of attenuating this variability, a situation not well recognized previously Previous theoretical and experimental work is critically reviewed throughout this paper

The effect of distributed series resistance on the dark and illuminated current&#8212;Voltage characteristics of solar cells

The series resistance (Rs) of a solar cell is commonly represented as a constant resistance value. However, because of the distributed nature of series resistance, the effective lumped Rs vary with current density and illumination intensity. Treating Rs as a constant is usually insufficient for an accurate analysis of its J–V curve. This work first presents a review of the distributed nature of series resistance and commonly applied methods to measure Rs. Particular attention is given to the multi-light method (MLM) and it is discussed in detail, where Rs in both the light and dark can be measured as a function of current by extracting Rs from a set of current–voltage (J–V) curves attained at different illumination intensities. The principle behind this method is discussed, and the results are then compared with those of other known methods of Rs measurement. The accurate measurement of Rs(J) attained with the MLM permits the extraction of an Rs-corrected J–V curve, which is theoretically more accurate than that attained by alternative methods because of negligible error from injection dependence and spectral mismatch. With the solar cell equation modified to include Rs(J), we attain a much better fit to experimental data, finding a significant reduction in error compared with using a constant Rs. Copyright © 2011 John Wiley & Sons, Ltd.

Accurate Series Resistance Measurement of Solar Cells

Evaluation of five types of silicon photodiode was undertaken to verify their suitability for absolute radiometry and also for their use as transfer standards in the spectral region from 1 nm to 1100 nm. Four types of photodiode were fabricated for this study; these were the p-on-n photodiode, n-on-p photodiodes with silicon dioxide front windows and n-on-p photodiodes with a metal-silicide front window. Fabrication of photodiodes with 100% internal quantum efficiency is demonstrated and their necessity for making absolute radiometric measurements with the lowest possible uncertainty is pointed out. The linearity characteristics of these devices, as measured by the ac/dc method, are far superior to those of the p-on-n diodes especially fabricated for this work and also to those exhibited by p-on-n diodes widely used at present by the radiometric community. Results on the stability of the quantum efficiency of the fabricated diodes after exposure to intense radiation of 13 nm, 120 nm, 157 nm, 193 nm and 254 nm radiation will also be presented. Photodiodes with a metal-silicide front window were the only devices stable when exposed to the intense beams of third-generation synchrotrons and UV excimer lasers.

https://iopscience.iop.org/article/10.1088/0026-1394/40/1/333/pdf

Present status of radiometric quality silicon photodiodes

The effect of the diode ideality factor on the experimental determination of series resistance of solar cells

A simple technique for the measurement of series resistance of concentrator solar (photovoltaic) cells is described. This technique makes use of the fact that the ’’short circuit’’ current of a solar cell as a function of light intensity will begin to saturate at an intensity determined by the series resistance of the cell and circuit. In this region the series resistance of the cell can easily be found from a measurement which is relatively independent of illumination intensity and spectrum. Experimental data are presented that verify this result.

R. J. Chaffin

Papers

Measurement of concentrator solar cell series resistance by flash testing