Solar Panels to Power Smartwatch and TV Remote Launching in 3 Years

The Future of Home Electronics: Solar-Powered Devices on the Horizon

How many of us have spent weeks rubbing together the batteries of our TV remotes to get a bit more life out of them before finally biting the bullet and buying some new ones? This could soon be an irritation of the past, thanks to miniature solar panels. Scientists have discovered a way to turbocharge the efficiency with which solar panels can convert indoor light into electricity, paving the way for tiny solar cells to be used in place of batteries for a range of home electronics – including radios, keyboards, and smoke alarms.

The scientists behind the project are in talks with developers and say that, if all goes according to plan, the first of this new generation of solar-powered sensors, alarms, and remote controls could start to become available in the shops within two to three years. The devices could also include fitness trackers, smartwatches, health monitoring patches, hearing aids, and smart light switches.

Although the solar cells are not yet efficient enough to be able to power mobile phones, researchers are hopeful they may be used to top up a phone’s battery life – meaning they could go longer without charges. And in the longer term, they say the technology could be developed to power not only phones but bigger home devices such as vacuum cleaners and TVs.

Artificial indoor light has different wavelengths from the sun, meaning that conventional outdoor solar panel materials do not work well inside. The researchers envisage a future in which devices all over the home are powered with solar cells – saving households the hassle of replacing batteries and helping the environment, since batteries contain toxic materials.

“Billions of devices that require small amounts of energy rely on battery replacements – an unsustainable practice,” said Dr Mojtaba Abdi-Jalebi, of University College London. “Currently, solar cells capturing energy from indoor light are expensive and inefficient. Our indoor solar cells can harvest much more energy than existing commercial cells, paving the way for electronics powered by ambient light.”

“We’re in early-stage discussions with industry partners. The technology is at an advanced prototype stage. If development progresses smoothly, we hope to see products using this technology in the UK and globally within two to three years, starting with low-power home electronics.”

Advancements in Solar Cell Technology

The perovskite photovoltaic solar cells they engineered are about six times more efficient than the best commercially available indoor solar cells – which are so expensive they are only used in a handful of expensive items, such as watches. Furthermore, they are more durable than alternative cells, as they can be used for an estimated five years or more, rather than just a few weeks or months.

Neil Saunders, who heads the retail unit at the GlobalData business analysis group, believes there would be strong demand for solar-powered sensors, alarms, and remote controls. “If the products look good and are reasonably priced, then there will likely be consumer interest. Replacing batteries isn’t the biggest hassle, but it’s a hassle nonetheless – especially in terms of ensuring the correct battery is available,” he said.

“There has not been much evolution in this area. If consumers could simply forget about batteries that would be helpful. It also comes with a cost attached as batteries are not cheap.”

Professor Pablo Docampo, a scientist at the Basque Centre for Materials, Applications and Nanostructures in Spain, who was not involved in the research, told The i Paper that the development “is really exciting…a two to three-year timeframe sounds realistic” for the technology to become available.

“These could be anything from humidity sensors (maybe to trigger automatic watering of plants in windowsills), to pollution sensors (every time you turn the gas hob on, you fill your kitchen with toxic gases) – knowing the concentration is something that I would personally like to know,” he said.

Scientific Breakthroughs

The material used – perovskite – is increasingly used in outdoor solar panels and unlike with traditional silicon-based solar panels, it can be adjusted to better absorb the specific wavelengths of indoor light. But it has a flaw. Tiny defects in its crystal structure – known as “traps” – are caused by missing atoms that act like potholes in a road and interrupt the flow of electricity, causing energy to be lost as heat.

The scientists managed to overcome this by adding a chemical – rubidium chloride – that helps the perovskite crystals to form more evenly when they grow, significantly reducing the number of traps. Two more chemicals were added – organic ammonium salts known as N-dimethyl octyl ammonium iodide and phenethylammonium chloride – which helped hold the material together. This reduced the number of gaps occurring in the crystals that further interrupt the flow of electricity – increases the cell’s efficiency and durability.

“Solar cells with these tiny defects are like a cake cut into pieces,” Siming Huang, of University College London, told The i Paper. “The three ingredients we added have put this cake back together again, allowing the charge to pass through it more easily.”

The researchers found that their solar cells converted 37.6 per cent of indoor light (at 1,000 lux – equivalent to a well-lit office) into electricity, a world record for this type of solar cell that has been optimised for indoor light. After more than 100 days, the newly engineered cells retained 92 per cent of their performance, compared to a control device that retained 76 per cent of its initial performance.

Dr Abdi-Jalebi said: “Currently, indoor solar cells are low efficiency and quite costly when customised for indoor use – £5 to £10 extra per product. With our perovskite solar cells, we expect the cost to drop to around £2–£3 extra per device once in large-scale production, with much better performance and lifespan.”

The research is detailed in the journal Advanced Functional Materials and involved scientists from Imperial College London, South Bank University, Ordos New Energy Research Institute in China, and the Swiss Federal Technology Institute of Lausanne.