In order to decrease the thickness of the close-spaced sublimation (CSS) deposited CdTe film, a novel approach has been used. On top of the CSS-deposited CdTe film, whose thickness was reduced from 6-8 μm to 3-4 μm, another CdTe layer was deposited by RF sputtering, with a thickness of 100-200 nm. The purpose of this approach was that of filling up the voids, which form when a low thickness CdTe film is deposited by CSS. Surprisingly we observed that solar cells prepared with this CdTe bi-layer exhibit efficiencies higher than 14%. Since the sputtered CdTe layer is n-type, while the CSS-deposited one is p-type, we thought to explain these results by supposing the formation of local p-n junctions at the grain boundaries, which repel the minority carriers in the grains, increasing their lifetime. This approach permitted to reduce the thickness of CdTe films without affecting the cell efficiency. A further improvement in processing CdTe/CdS solar cells has been obtained by making the CdTe treatment in presence of Chlorine with the use of Ar containing 4% HCl mixed with a gas containing Fluorine, such as CHF3 or C2H2F4.

Improvement in Processing CdTe/CdS Thin Film Solar Cells / Romeo, N.; Bosio, A.; Menossi, D.; Rosa, G.; Salavei, A.; Romeo, A.. - CD-ROM. - (2014), pp. 1709-1712. ((Intervento presentato al convegno 29th European Photovoltaic Solar Energy Conference and Exhibition (EU PVSEC) [10.4229/EUPVSEC20142014-3DV.1.15].

Improvement in Processing CdTe/CdS Thin Film Solar Cells

ROMEO, Nicola;BOSIO, Alessio;MENOSSI, Daniele;ROSA, GRETA;
2014

Abstract

In order to decrease the thickness of the close-spaced sublimation (CSS) deposited CdTe film, a novel approach has been used. On top of the CSS-deposited CdTe film, whose thickness was reduced from 6-8 μm to 3-4 μm, another CdTe layer was deposited by RF sputtering, with a thickness of 100-200 nm. The purpose of this approach was that of filling up the voids, which form when a low thickness CdTe film is deposited by CSS. Surprisingly we observed that solar cells prepared with this CdTe bi-layer exhibit efficiencies higher than 14%. Since the sputtered CdTe layer is n-type, while the CSS-deposited one is p-type, we thought to explain these results by supposing the formation of local p-n junctions at the grain boundaries, which repel the minority carriers in the grains, increasing their lifetime. This approach permitted to reduce the thickness of CdTe films without affecting the cell efficiency. A further improvement in processing CdTe/CdS solar cells has been obtained by making the CdTe treatment in presence of Chlorine with the use of Ar containing 4% HCl mixed with a gas containing Fluorine, such as CHF3 or C2H2F4.
3-936338-34-5
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11381/2815992
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