Episode 8: Ge added to lead-free perovskite improves efficiency

Research on perovskites has progressed rapidly for PV and LEDs, with new solar-cell efficiency records being set at a regular pace. There are hints of the first commercial products reaching the market by 2020, just a decade since perovskite photovoltaics were first discovered. MRS Bulletin presents the impact of a recent advance in this burgeoning field.

Read the article in Nature Communications (doi:10.1038/s41467-018-07951-y).

Transcript
Welcome to MRS Bulletin’s Materials News Podcast, providing breakthrough news & interviews with researchers on the hot topics of 3D bioprinting, artificial intelligence and machine learning, bioelectronics, perovskites, quantum materials, robotics, and synthetic biology. My name is Bob Braughler. 

The presence of lead in state-of-the-art perovskite solar cells could hold back their commercialization. Lead-free alternatives based on tin compounds have shown promise, but they typically suffer from low efficiency and stability.

Brown University’s Yuanyuan Zhou and Nitin Padture and their colleagues have made a surprising discovery that provides a solution. They found that simply adding germanium to the lead-free perovskite cesium tin iodide, which degrades easily, makes it air-tolerant. Devices made with the new perovskite show an efficiency of 7.11% and remain highly stable after 500 hours of operation under 1-sun illumination. The key to this behavior is the extremely high oxidation activity of germanium, which forms an ultrathin, uniform oxide layer on the surface, which—as the researchers write—“fully encapsulates and passivates the perovskite surfaces.”   

This work was published in a recent issue of Nature Communications. My name is Bob Braughler from the Materials Research Society.

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