Photocurrent in CdTeNIP solar cells

A simple analytical model for the voltage dependence of the photocurrent in CdTe n-i-p solar cells is presented. The physical model is corroborated wi th a numerical solution of Poisson and the two continuity equations under i llumination and shows excellent agreement with the numerical data. The new model is compared with previously reported models of Bube and Crandall. The new model illuminates the loss mechanism of carriers near the front interf ace of CdTe solar cells. It is shown that the photocurrent is high when the carrier velocity due to the electric field is higher than the product of t he absorption coefficient and the diffusion coefficient, almost regardless of the interface recombination velocity value. At lower electric field valu es, the interface recombination velocity has a stronger effect on the photo current. Experimental conditions leading to a reduction of the electric fie ld and a corresponding decrease in the collection efficiency in CdTe n-i-p solar cells are discussed. (C) 2000 Elsevier Science B.V. All rights reserv ed.