New tiny solar cells may power personal devices

Washington: Scientists have created high-performance, micro-scale solar cells that outshine comparable devices and could power personal devices such as wearable medical sensors, smartwatches and autofocusing contact lenses.

Large, rooftop photovoltaic arrays generate electricity from charges moving vertically. The new, small cells, developed by researchers at the University of Wisconsin-Madison in the US capture current from charges moving side-to-side, or laterally.

They generate significantly more energy than other sideways solar systems. New-generation lateral solar cells promise to be the next big thing for compact devices because arranging electrodes horizontally allows engineers to sidestep a traditional solar cell fabrication process - the task of perfectly aligning multiple layers of the cell's material atop one another.

"From a fabrication point of view, it is always going to be easier to make side-by-side structures," said Hongrui Jiang, professor at UW-Madison. "Top-down structures need to be made in multiple steps and then aligned, which is very challenging at small scales," said Jiang.

Top-down photovoltaic cells are made up of two electrodes surrounding a semiconducting material like slices of bread around the meat in a sandwich.