Nanotechnology harnesses sun

Solar-powered cellphone batteries may soon be able to almost double the battery life of mobile technology, and batteries could be recharged without being plugged in.

New Zealand nanotechnologist Brendan Kayes, who has worked at Silicon Valley company Alta Devices since 2009, is developing solar cells so efficient and lightweight they increase battery life on mobile devices by up to 80 per cent.

Using the solar technology being developed by the company, mobile devices would still require a battery to be charged from a wall outlet, but could also be charged by leaving them in full sunlight.

"We are already producing chargers of various kinds, but not yet for retail sale," Dr Kayes, who studied physics, mathematics and philosophy at Auckland University, said.

A engineering scientist and senior engineer at Alta Devices, Dr Kayes hopes the technology will be available to consumers as soon as 2015.

The company has already built prototype solar cases for iPhones and the Samsung Galaxy S3, and the technology could easily be applied to other smartphones.

The 33-year-old Aucklander first became seriously interested in solar energy in 2001 after he received a scholarship to attend a two-week Alliance for Global Sustainability conference in Switzerland.

Inspired, he headed to the United States to further his studies, completing a PhD in applied physics in 2009 at the California Institute of Technology.

He started working at Alta Devices immediately after graduating.

Unlike solar chargers currently on the market, the cells developed by Alta Devices were highly efficient and would even work under artificial light.

"Our technology provides several times the power per unit area of the best flexible solar options currently available for consumer devices," Dr Kayes said.

"We can fit four to five of our cells on the back of a cellphone. That means roughly one watt of charge under direct sun.

"Every minute the phone is in the sun you get a minute of talking time," he said.

Justin Hodgkiss, a nanotechnologist at Wellington's MacDiarmid Institute, said Dr Kayes' work was significant, developing the highly efficient material into something that was also light and flexible.

"To me the breakthrough is that they figured out a way to make highly-efficient cells flexible - usually those two things are incompatible," Mr Hodgkiss said. He said that usually in solar technology flexibility and being light-weight do not go hand-in-hand with efficiency.

"Even the panels that you see on a calculator are not really flexible. They are similar to the ones you would find up on the roofs of buildings. They are brittle, they're solid. They're like big panes of glass.

"[And] your smartphone needs a lot more power than a calculator to charge."

The repercussions of this technology could go well beyond charging a dead phone.

According to Alta Devices' website, the US Army is currently using the company's cells to take the strain off generators, and there is even the possibility of using them to increase fuel economy in cars and unmanned aircraft, and to integrate them into backpacks, tents and clothing.

Susan Strongman is a Witt journalism student

Taranaki Daily News