Measurements on monocrystalline CuInSe2 cells

A series of measurements has been made on a number of photovoltaic cells fabricated with the layer structure Au-CuInSe₂-CdS-ZnO-In, where the CuInSe₂ consisted of a wafer of p-type monocrystalline material cut from an ingot grown by a vertical Bridgman method. A plot of conversion efficiency (η) and short circuit current density (j_SC) against cell series resistance (R_AS), obtained from dark current-voltage characteristics, indicated a general increase of η and j_SC with decrease of R_AS. The measurements also showed a general increase of j_SC with increase of the apparent hole concentration, p_MS, obtained from Mott-Schottky plot slopes. Minority diffusion length estimates, obtained by the photo-current-capacitance method, were found to decrease with increase of p_MS. As a result, surprisingly, diffusion lengths were smaller in the better performance cells. The best monocrystalline CuInSe₂ cell had an original total area efficiency of 11.4% (or 12.5 %, active area), without an A.R. coating.