Devising a technique to improve the efficiency of CdS/CdTe/Cu/Au solar cells intended for use as a backup power source for the systems of safety and control of objects

This paper reports a study into the impact of cadmium telluride layer thickness on the effectiveness of the CdS/CdTe/Cu/Au film solar cells. The physical mechanisms have been investigated of charge transfer in the CdS/CdTe/Cu/Au solar cells, which are intended for use as a backup power source for the systems of safety and control of objects. This is important because, despite the growing popularity of solar cell application, the effectiveness of laboratory samples differs greatly from the theoretical maximum. Thus, it has been established that the optimum thickness of the base layer of film CdS/CdTe/Cu/Au SCs is 4 µm. When the thickness of the cadmium telluride layer is reduced, the effectiveness of such an assembly decreases. The decrease in efficiency occurs as a result of reducing the shunting electric resistance, increasing the density of a diode saturation current, as well as consistent electric resistance. With the increase in the thickness of the telluride layer exceeding 4 µm, there is also a decrease in the efficiency of a solar cell due to the reduced shunting resistance and the increased serial electric resistance. The deterioration of the specified light diode characteristics of CdS/CdTe/Cu/Au SCs, which occurs when the thickness of the base layer is reduced by more than 4 µm, is due to the diffusion of copper from the contact to the area of the separating barrier. The deterioration of light diode characteristics when increasing the thickness of the base layer of cadmium telluride is associated with a decrease in the positive effects of chloride treatment. The examined physical charge transfer mechanisms in the CdS/CdTe/Cu/Au solar cells have made it possible to establish the height of the rear potential barrier. In the samples studied, the height of the rear potential barrier is 0.3 eV. The existence of such a barrier gives rise to the thermal-emission mechanism of charge transfer in such solar cells when applying a direct offset exceeding 1 V