University of Wisconsin–Madison engineers have created high-performance, micro-scale solar cells that outshine comparable devices in key performance measures. The miniature solar panels could power a myriad of personal devices, such as wearable medical sensors, smart watches and even auto-focusing contact lenses, according to information provided by the university.
Large, rooftop photovoltaic arrays generate electricity from charges moving vertically. The new, small cells, described in Advanced Materials Technologies, capture current from charges moving side-to-side, or laterally, and they generate significantly more energy than other sideways solar systems.
New-generation lateral solar cells hold promise for compact devices because arranging electrodes horizontally allows engineers to sidestep a traditional solar cell fabrication process: the arduous 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,” says Hongrui Jiang, a UW–Madison professor of electrical and computer engineering and corresponding author on the paper. “Top-down structures need to be made in multiple steps and then aligned, which is very challenging at small scales.”
Existing top-of the-line lateral new-generation solar cells convert merely 1.8 percent of incoming light into useful electricity. Jiang’s group nearly tripled that measure, achieving up to 5.2 percent efficiency.
“In other structures, a lot of volume goes wasted because there are no electrodes or the electrodes are mismatched,” says Jiang. “The technology we developed allows us to make very compact lateral structures that take advantage of the full volume.”
Jiang and colleagues are working to make their solar cells even smaller and more efficient by exploring materials that further optimize transparency and conductivity. Ultimately they plan to develop a small-scale, flexible solar cell that could provide power to an electrically tunable contact lens.
Other authors on the paper included Xi Zhang, Yinggang Huang, Hao Bian, Hewei Liu, and Xuezhen Huang. The National Institutes of Health provided funding for the research.