The Solar Cell Discovery Machine – IEEE report

With the aid of crystals known as perovskites, solar cells are increasingly breaking records in how well they convert sunlight to electricity. Now a new automated system could make those records fall even faster. North Carolina State University’s RoboMapper can analyze how well perovskites might perform in solar cells, using roughly one-tenth to one-fiftieth the time, cost, and energy of either manual labor or previous robotic platforms, its inventors say.

The most common solar cells use silicon to convert light to electricity. These devices are rapidly approaching their theoretical conversion efficiency limit of 29.4 percent; modern commercial silicon solar cells now reach efficiencies of more than 24 percent, and the best lab cell has an efficiency of 26.8 percent.

One strategy to boost a solar cell’s efficiency is by stacking two different light-absorbing materials together into one device. This tandem method increases the spectrum of sunlight the solar cell can harvest. A common approach with tandem cells is to use a top cell made of perovskites to absorb higher-energy visible light and a bottom cell made of silicon for lower-energy infrared rays. Last year scientists unveiled the first perovskite-silicon tandem solar cells to pass the 30 percent efficiency threshold, and last month another group reported the same milestone.

Conventional materials research has scientists prepare a sample on a chip and then go through multiple steps to examine it using different instruments. Existing automation efforts “tend to emulate human workflows—we tend to process materials one parameter at a time,” says Aram Amassian, a materials scientist at North Carolina State University, in Raleigh ….

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