A Technical Review on the Thin-Films Coatings for Enhancing the Efficiency of the Photo-Voltaic Cells for Solar Energy Applications

In the recent years, solar energy is being harnessed by using two technologies - solar photo-voltaic (PV) cells and solar thermal methods. The PV technology is based on the conversion of solar energy into electricity, which is subsequently fed into a grid to power lighting, heating and cooling systems. Nowadays, PV systems are mainly available in the form of flat - plate and concentrator panels. PV solar panels are made by using mono crystalline, poly crystalline, amorphous and thin - film varieties. A solar cell is basically a fine silicon wafer. Currently, crystalline silicon panels are the most commonly used PV systems. These devices are developed using specific combinations of solar cells. Basically, PV systems are available in two designs, which are flat - plate and concentrator panels. As of now, all PV solar panels sold in India are fabricated by using crystalline silicon cells. An advantage of this technology is that these panels are eco - friendly to use, and also do not emit greenhouse gases. However, silicon is quite expensive and also in short supply. Companies are researching alternatives such as thin film systems as well as other non - silicon options to bring down the cost of production and make PV solar panels widely accessible. More recently, Thin-film technologies are being used as they do not use polysilicon, and an added advantage is that the production of thin films is less expensive than that of the silicon cells. This is because they are made up of thin layers in the form of wafers of photosensitive material and also the manufacturing process consumes less energy. This paper reviews technically the various types of photovoltaic cells, applications of PV cells, improvements in the efficiency of the PV devices, constituents materials and underlying principle of the PV cells, thin films coatings being employed for making the systems to be used as non-conventional energy sources. The PV technologies and the trends in this area have also been briefly discussed.