Crystals could make efficient solar cells

Cheap and easy-to-produce crystals could one day outperform silicon in solar cells and other electronic devices. An international team has shown that organolead trihalide perovskite crystals have the potential to conduct as effectively as silicon, if the crystals are prepared using a new technique outlined in Science¹.  

Recently, engineers have found that cells made from perovskite crystals are almost as good at transforming energy from sunlight into electricity as the most established solar cell materials — with an efficiency of about 20%. 

Now Osman Bakr, a materials scientist at the King Abdullah University of Science and Technology (KAUST) in Saudi Arabia and his colleagues have grown particularly smooth perovskite crystals. This is important because defects in the crystals can obstruct the flow of charges, reducing the efficiency of a solar cell. 

The crystals were made by mixing the compound’s ingredients in solution. Through a process of trial and error, the team found the perfect “antisolvent”, dichloromethane, which, when added to the mixture, caused all of its components to precipitate at the same rate and form smooth and large crystals with hardly any defects. 

Charges were able to travel tens of micrometres within the crystals before being obstructed — comparable to the highest grade silicon used in solar cells. “This shows that the performance of perovskite cells could be further improved and perhaps soon could surpass silicon-based solar cells,” says Bakr. 

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