Solar power is an increasingly mainstream technology, and you can now get solar chargers for your phone, solar-powered clothes, and rollable solar panels. But most of us spend most of our time indoors, with only minimal sunlight exposure. So what if we could charge devices using the ambient light we do have — light from indoor sources like desk lamps?
A group of scientists working on a technology called organic photovoltaics (OPVs) aim to do just that. The team from Kyushu University, Japan, has developed special light harvesters which are optimized to produce energy from ambient indoor lighting. They used OPVs, a type of organic solar cell which absorbs light and converts it into electricity, then tweaked them to absorb artificial indoor light instead of the Sun’s rays.
OPVs also have the advantage of being lightweight, thin, and flexible, meaning they could potentially be applied to all sorts of surfaces to charge a wide variety of devices. The efficiency of the OPVs is also better than you might expect, at 16 percent efficiency under white LED illumination, making them comparable in efficiency to most solar panels which absorb energy from the Sun.
Of course, users would still need to use electricity to power their light sources, so such panels wouldn’t reduce overall electricity consumption by a huge amount. But if lights are going to be on anyway, as they usually are when people are occupying a room, then the extra light energy might as well be used to meet small power requirements like charging a phone.
The system tested by the researchers was a set of panels with an active area of about four inches squared, so it would be small enough to fit conveniently on a desk. At that size it produced voltage of 4.2 volts, not far off the 5 volts which is typical for a phone charger. However, the power produced is far too low for regular use, with output in the milliwatt range rather than the watt range required for most electrical items in the home.
So don’t expect to be charging your iPhone from your desk lamp just yet, but one day in the future we could charge our devices using indoor “solar” panels.
The research is published in the journal Applied Materials & Interfaces.