Super-Efficient Solar to Hydrogen System Uses Earth-Abundant Materials

At the Laboratory of Photonics and Interfaces at the Swiss Federal Institute of Technology in Lausanne (EPFL), scientists have developed methods for generating fuels such as hydrogen through solar water splitting. To do this, they either use photoelectrochemical cells that directly split water into hydrogen and oxygen when exposed to sunlight, or they combine electricity-generating cells with an electrolyzer that separates the water molecules. By combining a pair of solar cells made with the mineral perovskite and low-cost electrodes, EPFL scientists have now obtained a 12.3% conversion efficiency from solar energy to hydrogen - a record using earth-abundant materials as opposed to rare metals. Perovskite cells can generate an open circuit voltage greater than 1 V - for comparison, silicon cells stop at 0.7 V. The conversion of solar energy into hydrogen makes its storage possible, which addresses one of the biggest disadvantages faced by renewable electricity - the requirement to use it at the time it is produced.