Limitations on Thickness of Absorber Layer in CdS/CdTe Solar Cells

Abstract

Calculations of the integrated absorptive capacity of CdTe layer taking into account the spectrum of the AM1.5 solar radiation and the absorption coecient of CdTe are carried out. The recombination losses at the front and rear surfaces of the CdTe layer and in the space-charge region are also calculated based on the continuity equation. The restrictions on the thickness of CdTe in CdS/CdTe heterojunction have been ascertained taking into account all types of losses. It is shown that in CdTe, the almost complete absorption of photons (99.9%) in the hν > Eg range is observed at a layer thickness of more than 2030 µm, and the absorptive capacity of photons in a CdTe layer of thickness 1 µm is about 93%. The obtained results indicate that when the CdTe absorber layer is very thin, it is impossible to avoid a noticeable decrease of the short circuit current density Jsc as compared with a typical thickness of the absorber layer. The loss in Jsc is 1920% when the thickness is 0.5 µm compared to 5% for a thickness of 23 µm.

The Performance Optimization of Thin-Film Solar Converters Based on n-ZnMgO / p-CuO Heterojunctions

“…Apart from the absorption processes in solar cell layers, the transmittance of the light in CuO absorbing layer can be defined by the formula T  1 -R. So transmittance of the photovoltaic converter with a multilayer structure can be found by the formula [16,19]:…”