Solar panel technology has changed the way many people bring energy into their homes, but this type of technology has always posed one concern: panels cannot output optimal power without ideal weather conditions. When you have rainy days or a lot of cloud cover, there is only so much energy that panels can store for later use. While engineers and material scientists have been able to make their efficiency far better over the years, with solar panels that store decent amounts of energy to be used when sun is not readily available, there has never quite been a development like the one discovered this year.
Chinese scientists are now able to create electricity with the assistance of raindrops. This is thanks to a thin layer of graphene they use to coat their solar cells during testing. Graphene is known for its conductivity, among many other benefits. All it takes is a mere one-atom thick graphene layer for an excessive amount of electrons to move as they wish across the surface. In situations where water is present, graphene binds its electrons with positively charged ions. Some of you may know this process to be called as the Lewis acid-base interaction.
These new solar cells can be stimulated by incident light on sunny days and raindrops when it’s raining, yielding an optimal energy conversion efficiency of 6.53 % under 1.5 atmosphere thickness irradiation and current over µA, along with a voltage of hundreds of mV by simulated raindrops.
The salt contained in rain separates into ions (ammonium, calcium and sodium), making graphene and natural water a great combination for creating energy. The water actually clings to the graphene, forming a dual layer (AKA pseudocapacitor) with the graphene electrons. The energy difference between these layers is so strong that it generates electricity.
These new all-weather solar cells are discussed in depth in the Angewandte Chemie journal.