Engineers and materials scientists have made solar panels increasingly efficient, but the technology still requires the cooperation of the weather. Currently, slow-moving rain fronts spell bad news for solar power generation -- but not for a new prototype solar cell developed by a team of Chinese scientists.

By coating a solar cell in a thin layer of graphene, researchers have empowered the technology to turn raindrops into electricity.

Graphene is prized by materials scientists for its wide variety of benefits, one of them being conductivity. The one-atom-thick layer of carbon atoms allows a plethora of electrons to move freely across its surface. In water solutions, graphene binds positively charged ions with its electrons -- a process known as the Lewis acid-base interaction.

Because raindrops contain salts, which dissociate into ions, precipitation and graphene make an ideal electricity-producing pair. The rain's positively charged ions -- including sodium, calcium, and ammonium ions -- adhere to the graphene surface and form a double layer with the graphene's electrons.

The double layer is known as a pseudocapacitor, and the potential energy difference between the two layers is strong enough to generate an electric current.

Researchers described the new technology in the journal Angewandte Chemie.