What are Thin Film Solar Cells

Thin film solar cells are composed of layers of semiconductor material only a few microns thick, which are sandwiched between a transparent conductive oxide and a back contact. These layers can range from a few nanometers to tens of microns thick. This is considerably thinner than traditional bulk solar cell materials, which are normally greater than 200 microns. Typical thin film solar cells include amorphous silicon (a-Si:H), cadmium telluride (CdTe) and copper indium gallium selenide (CIGS).

Advantages of Thin Film Solar Cells

Thin film solar cells offer the possibility of reducing the quantity of active material, therefore expanding the range of potential materials for solar cell production. Although the efficiencies of thin-film solar cells are generally less than their bulk crystalline counterparts, the smaller material requirements and development of new production methods are driving down the cost. This has resulted in thin film silicon solar cells now having a larger market share than traditional crystalline silicon. Furthermore, CdTe solar cells have become the first to drop below $1/Wpeak for PV applications, which is a significant achievement. Due to their flexibility, thin film cells can double as roof top tiles or building facades. They also exhibit a relatively small drop in power output under partial shadowing, compared to crystalline silicon cells.

What are the challenges for Thin Film solar cells?

Cell stability and complexity of the manufacturing process are the major challenges holding thin film back.  Scaling up of the manufacturing process has revealed particular difficulties; especially when challenging against silicon, which has benefited from the electronic manufacturing industry. Developing efficient techniques for the fabrication and characterisation of thin film materials is required at all levels of thin film material research. This is where the study of surface science can play a critical role.

Thin film solar cells are composed of thin flat layers stacked sequentially. Therefore understanding the properties of the interface between these layers is essential to maximise cell efficiency. A dedicated surface science facility is available at the Thin Film Centre, based at the University of the West of Scotland. The centre carries out research and development of deposition and characterisation of thin films of material. 

Please click on the links below to learn more about the different types of thin film solar cells and the work being carried out by SISER researchers.