A simple method to extract the diffusion length from the output parameters of solar cells - application to polycrystalline silicon

TARETTO, K. R.; RAU, U.; WAGNER, T. A.; WERNER, J.-H.

DIFFUSION AND DEFECT DATA, SOLID STATE DATA. PART B, SOLID STATE PHENOMENA

Scitec

Lugar: Zurich; Año: 2003 p. 399 - 404

1012-0394

This work presents a simple method to obtain the effective diffusion length Leff of a solar cell directly from measured values of open circuit voltage, short circuit current density, and the doping density in the base of the cell. In the second part of this paper, we extract Leff from literature data of polycrystalline silicon cells, with grain sizes from 10-2 to 104 µm, modeling the extracted Leff as a function of the grain size g, and the recombination velocity SGB at the grain boundaries. For g > 1 µm, our model predicts 105 < SGB < 107 cm/s. Cells with g < 1 µm, are understood with 101 < SGB < 103 cm/s. This finding supports the hypothesis that the key to high efficiencies at small grain sizes is the use of {220}-textured films.