Solar cell manufacturing process examined with a view to increasing cell efficiency

Electro-optical characterization of in-situ indium doped CdS thin films by chemical bath

As the world becomes increasingly aware of global warming and climate change, the need for alternative energy sources is generating greater demand. Electricity generated from solar cells is often quoted as being the solution to our climate problems. Unfortunately, this method of energy generation is quite inefficient. Overcoming this inefficiency is key to the widespread commercial acceptance of solar energy.

Recent years have seen Indium doped Cadmium Sulfide thin films gain importance as photovoltaic devices. Various techniques have been used to make the CdS:In thin films with chemical baths being most widely used. Due to this acceptance of the manufacturing method, it is important to develop an effective technique to n-dope CdS thin films during the growth process.

In this journal* article by Mexican researchers, J. A. Dávila-Pintle, R. Lozada-Morales, R. Palomino-Merino, B. Rebollo-Plata, C. Martínez-Hipatl, O. Portillo-Moreno, S. Jiménez-Sandoval and O. Zelaya-Ángel, from Benemérita Universidad Autónoma de Puebla and Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional looked to increase the carrier density and to reduce the electrical resistivity of the material – with no sensitive reduction of the forbidden energy band gap. In order to achieve this goal they employed the chemical bath in such a way as to analyse the doping method to determine the most effective dosage resulting in good physical properties useful for a wide field of applications.

The experimental results indicate a successful doping for low indium dosages, a saturation for intermediate doping levels, and a degradation of the doping process for high impurity. Furthermore, they were able to produce the CdS films more efficiently with electronic testing results indicating that this n-type doping process is suitable for producing CdS photovoltaic solar cells.