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Model of mixing ratio dependence of built-in voltages in organic bulk heterojunction solar cells

Y. WANG1, C. MA1, R. WANG1, R. LI1, Y. PENG1,2,*

Affiliation

  1. School of Physical Science and Technology, Lanzhou University, Lanzhou 730000, China
  2. The Key Laboratory for Magnetism and Magnetic Materials of the Ministry of Education, Lanzhou University, Lanzhou 730000, China

Abstract

Bulk heterojunction has emerged over the past years as a promising structure for organic solar cells. Different materials for electron and hole contact are usually used for most optimized devices, which results in a built-in voltage. Based on the double Gaussian distribution of density of states of bulk junction materials, a numerical model for the built-in voltage of bulk heterojunction solar cells is developed. The result show that the built-in voltage of a bulk heterojunction solar cells is strongly dependent on the mixing ratio. Compared with the built-in voltage of the pure devices (with pure donor material or pure acceptor material), the built-in voltage of bulk heterojunction solar cell is larger than the smaller but smaller than the larger of the built-in voltages of the two pure devices. The result also show that the built-in voltage increases with the increase of the cathode Fermi level, which is characterized by two plateaus related to the filling of the LUMOs of the acceptor and that of the donor, respectively..

Keywords

Bulk heterojunction organic solar cells; built-in voltage; double Gaussian distribution.

Submitted at: Jan. 7, 2011
Accepted at: Feb. 17, 2011

Citation

Y. WANG, C. MA, R. WANG, R. LI, Y. PENG, Model of mixing ratio dependence of built-in voltages in organic bulk heterojunction solar cells, Journal of Optoelectronics and Advanced Materials Vol. 13, Iss. 2, pp. 165-169 (2011)