Improved photovoltaic method for measurement of minority carrier diffusion length applied to silicon solar cells

The photovoltage spectrum measured on back illuminated silicon solar cells of the PESC (passivated emitor solar cell) type without original bottom ohmic electrode is evaluated with the aim to find the diffusion length of minority carriers in bulk of the absorber (L). Two junctions, namely pn(+) junction of the cell and that spontaneously created on the free surface generally exist in such samples. They give rise to two signals of opposite signs with one point of exact compensation. Six parameters (including L) are needed to characterize the spectrum. Special simple arrangement removes influence of spontaneously created junction on the free surface, which, in this way, reduces the number of parameters needed for fitting to three and enhances reliability of the measurement. (C) 2001 Elsevier Science B.V. All rights reserved.