Solar energy

Layered solar panel

Solar cells combine two materials and convert sunlight more efficiently

FELICE FRANKEL/MITSolar cells combine two materials and convert sunlight more efficientlyFELICE FRANKEL/MIT

A new type of solar cell developed by researchers at the Massachusetts Institute of Technology (MIT) and Stanford University, both in the USA, could make it easier to produce photovoltaic cells more efficient than those used today in the construction of solar panels, whose surfaces convert solar energy into electricity.  The new cells combine two materials: a layer of silicon, which forms the base for most solar panels produced today, and a semi-transparent layer of a semiconductor material called perovskite, which is able to absorb higher-energy light particles.  Differently from the solar cells announced a few months earlier by the same researchers, in which the layers were superimposed and each had its own separate electrical connections, the new cells are composed of two connected layers that operate as a single device, controlled by a control circuit (Applied Physics Letters, March 24, 2015).  But a particular challenge must still be overcome before the project can advance further: low efficiency.  Silicon cells convert less than a quarter of the light they receive into electrical energy.  The initial version of the new cells had an efficiency of 13.7%, and the commercial version can achieve 15%.  According to the researchers, they already know how to boost these figures to 30%.  Photovoltaic energy production is on the rise, but still represents only a small portion of the world’s energy mix – roughly 1%.  In Brazil, it is even less significant, accounting for a mere 0.01% of the total.