Inorganic (opto)electronic devices (Photovoltaic cells)
In order to produce electricity and make the best use of sunlight through solar panels, many photovoltaic cells based on silicon, rare earths or plastics are on the market.
There is, however, a need to develop photovoltaic cells that use common, non-toxic elements and aim at being built on flexible surfaces (plastic or metal sheets).
CIGS cells are thinner than their crystalline counterparts and less hazardous to workers, manufacturers and the environment than cadmium telluride structures. They can also be manufactured by printing. In this case, the required elements are immersed as nanoparticles in an ink. A specific printer is used to deposit the various layers making up the cells, at room temperature and in a conventional environment (no vacuum, inert atmosphere, etc.). The structures produced by printing have therefore a lower yield than the others. Nevertheless, this manufacturing process has the advantage of speeding up production and making the most profitable use of materials.
Finally, the individual layers can be deposited by sintering.
Nanoparticles are spread by an electrospray system on precursors and then heated, but without reaching their melting temperature. They will then weld together to ensure cohesion in the deposited layers.
CIGS incorporate indium, an element whose reserves are constantly decreasing. However, replacing the cells in the CIGS is a real challenge as this absorbent is so effective. However, an alternative using the p-n junction principle has emerged since the end of the 2000s: the CZTS cell. CZTS cells can be manufactured under vacuum using sputtering, co-evaporation or pulsed laser deposition (PLD). Without using a vacuum, the cells can be assembled by electroplating, printing, spray pyrolysis (the various elements are projected onto a heated support) or by a sol-gel process (using simple chemical reactions).