BUILDING MORE EFFICIENT SOLAR CELLS

Solar cells must become efficient and less expensive in order to better compete with tradional, non-renewable sources of energy. Important steps have been taken toward realising this goal by researches in Spain and Germany. Solar cells fabricated from Copper Indium Gallium diSelenide(CIGS),significantly more efficient and converting incident sunlight into electricity and conventional cells made from amorphous Silicon (a-Si). The problem is that they are considerably more expensive to manufacture.


Two Spanish (CEMAT and INASMENT) and two German (IPE and ZSW) organisations specialising in renewable energy research combined their resources and knowledge to adress this challenge. Part of their research focused on various treatments of the metals used as supstraight for the CIGS film. The smoother the substrate, the better. Different methods, including electrochemical and mechanical polishing as well as SiOx deposition were tested on two metals :ferritici chromium steel and titanium.

The resulting foils were assessed for smoothness using atomic-scale analysis methods like Scanning Electon Microscopy(SEM), Atomic Force Microscopy(AFM) and Secondary Ion Mass Spectrometry(SIMS). The results of the analysis indicate that mechanical polishing is preferable. The Spanish and German scientist also evaluated the effectiveness of adding the electric and conductive layers on top of the foils to block contamination of CIGS film by the metallic substrate. The outcome of the joint effort is a new chemical treatment that eliminates harmfull elements before they accumulate to destructive levels. The consortium is looking to extend this researches further in order to ultimately make CIGS technology economically competitive with that of a-Si.