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International Journal of Photoenergy
Volume 2011, Article ID 976063, 5 pages
http://dx.doi.org/10.1155/2011/976063
Research Article

Charge-Carrier Transport in Thin Film Solar Cells: New Formulation

1Departamento de Física Aplicada, Universidad de Salamanca, 37008 Salamanca, Spain
2Departamento de Física, CINVESTAV del I.P.N., Apartado Postal 14-740, 07000 Mexico, DF, Mexico

Received 4 July 2011; Accepted 28 August 2011

Academic Editor: Leonardo Palmisano

Copyright © 2011 Jesús E. Velazquez-Perez and Yuri G. Gurevich. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Solar cells rely on photogeneration of charge carriers in p-n junctions and their transport and subsequent recombination in the quasineutral regions. A number of basic issues concerning the physics of the operation of solar cells still remain obscure. This paper discusses some of those unsolved basic problems. In conventional solar cells, recombination of photogenerated charge carriers plays a major limiting role in the cell efficiency. High quality thin-film solar cells may overcome this limit if the minority diffusion lengths become large as compared to the cell dimensions, but, strikingly, the conventional model fails to describe the cell electric behavior under these conditions. A new formulation of the basic equations describing charge carrier transport in the cell along with a set of boundary conditions is presented. An analytical closed-form solution is obtained under a linear approximation. In the new framework given, the calculation of the open-circuit voltage of the solar cell diode does not lead to unphysical results.