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The photoluminescence of CdTe thin films in SnO2-CdS/CdTe-Ni solar cells thermally treated in CdCl2 solution

I. CARAMAN1, G. I. RUSU2,* , L. LEONTIE2

Affiliation

  1. Bacau University, 157 Calea Marasesti, 600115 Bacau, Romania
  2. “Al.I. Cuza” University, 11 Carol I Bd., 700506 Iasi, Romania

Abstract

The photoluminescence (PL) spectra of CdS/CdTe heterojunctions from SnO2-CdS/CdTe-Ni solar cell structures prepared by quasiclosed volume technique are analysed. The heterojunctions have been thermally treated for 15 min up to 7.5 h, at temperature ~690 K, in a CdCl2 solution. The thermal treatment leads to formation of ionized centres, to whom excitons with energy 9-10 meV are bound, as well as of a layer of CdSxTe1-x solid solutions (0≤x≤0.75) at the heterojunction interface. By radiative annihilation of excitons from the heterojunction interface layer, a PL band peaked at 1.552 eV (at T=78 K) is formed. As a result of thermal treatment, the spectrum of recombination levels restructures and an impurity PL band with maximum at 1.44 eV forms. The long duration treatments result in the split of the impurity and exciton PL bands in two (sub)bands determined by the composition of heterojunction interface layer..

Keywords

CdS/CdTe solar cells, CdCl2 heatl treatment, Thin films, Photoluminescence.

Submitted at: Nov. 14, 2006
Accepted at: May 15, 2007

Citation

I. CARAMAN, G. I. RUSU, L. LEONTIE, The photoluminescence of CdTe thin films in SnO2-CdS/CdTe-Ni solar cells thermally treated in CdCl2 solution, Journal of Optoelectronics and Advanced Materials Vol. 9, Iss. 5, pp. 1546-1550 (2007)