Technique promises cheaper, more efficient solar cells

While it's been known for several decades that hydrogen atoms can be introduced to help correct the efficiency reducing defects and contaminants found in lower grade silicon, researchers have had limited success in controlling the hydrogen to maximise its benefits. The solution found by the UNSW team relates to controlling the charge state of the hydrogen atoms. Hydrogen atoms can exist in a positive, negative or neutral charge state, which determines how well they can move around the silicon and their reactivity. This is important to help correct the defects. The researchers say that by controlling the charge state, it will be possible to achieve higher efficiencies using lower cost, low grade silicon. Lead researcher Professor Stuart Wenham believes the technique could enable solar cells with efficiencies between 21 and 23%, compared to the current maximum efficiency of around 19%. He commented: "We have seen a 10,000 times improvement in the mobility of the hydrogen and we can control the hydrogen so it chemically bonds to things like defects and contaminants, making these inactive. "This process will allow lower quality silicon to outperform solar cells made from better quality materials."