Effects of the Au/CdTe back contact on IV and CV characteristics of Au/CdTe/CdS/TCO solar cells

Abstract

A simple analytical theory is presented to explain the measured roll over and cross over behaviour of the IV characteristics of thin film CdTe solar cells. It involves a classical description of the CdS/CdTe junction and the CdTe/back contact structure and is extended with a new description of minority carrier current in the CdTe contact region. This extension is crucial in describing the light dependence of the forward IV curves, and hence cross over. The same model also explains the measured CV curves. It is shown that analysis of the capacitance measurement can yield additional information about the doping density of CdTe in the vicinity of the contact. A relationship between the fill factor of the solar cell and the barrier height of the back contact is derived; this relation is useful as a new, practical criterion for the quality of the back contact. The results of this simple analytical model are confirmed by full numerical calculations of the dc and ac characteristics.

Injection Current Barrier Formation for RbF Postdeposition‐Treated Cu(In,Ga)Se2‐Based Solar Cells

“…In the case of a back barrier, for instance, a roll-over and current saturation of the I-V curve is expected. [23] For a barrier positioned at the front contact, the situation is more complicated as the barrier might also be dependent on illumination, and voltage [24] and a current saturation is not necessarily observed.…”

“…Additionally, the shape of the curves hints to the fact that the barrier for the experimental curves is located at the front contact, as a saturation of the current is expected for a barrier located at the back contact as mentioned above. [23] 3. Results Within the same temperature range, the short-circuit current density (J SC ) does not vary systematically.…”

Defect Spectroscopy on Damp-Heat Treated ZnO/CdS/Cu(In,Ga)(S,Se)2/Mo Heterojunction Solar Cells

“…This effect is also seen in the DH treated Schottky contacts [18]. The current vs. voltage measurements performed before and after DH testing do not indicate the formation of a back-contact barrier (for samples exposed to DH conditions as complete devices), a problem commonly reported for the case of standard CdTe-based solar cells [29].…”

Electrical Properties of RF Sputtered CdTe/CdS Thin Film Solar Cells

“…Multijunction solar cells although more efficient have higher fabrication cost. Polycrystalline thin film CdTe solar cells are one of the important candidates for large scale photovoltaic applications because of their low cost, high efficiency and stable performance [2] and have been used for large area terrestrial applications [3]. Cadmium telluride is an important material for the development of low cost photovoltaic devices for space as well as terrestrial applications [2,4].…”