Mapping the Energetic Landscape of Solar Cells

Artistic impression of an energetic landscape that determines the movement of photo-induced positive (h+) and negative (e-) charges in photovoltaic devices. (Source: Vaynzof)

A new spectro­scopic method now makes it possible to measure and visualise the energetic landscape inside solar cells based on organic materials. It was developed by a research team led by Yana Vaynzof, a physicist at Heidelberg Uni­versity. This novel visualisation technique enables scientists to study the physical principles of organic photo­voltaics with extreme precision and to better understand processes such as energetic losses.

“Mapping our Earth’s landscapes was a necessary step for under­standing the movement patterns and dynamics of people, animals and water, among other examples”, explains Vaynzof, research group leader at the Kirchhoff Institute for Physics at Heidelberg Uni­versity. “Simi­larly, the movement of electric charges in a solar cell is determined by the energetic landscape within the device.” Until now, visua­lizing these energetic landscapes was so challenging that only rough estimates could be used to study the funda­mental processes in organic photo­voltaic devices.

The spectro­scopic method can map the energetic landscape on a nanometre scale and can be applied at any point during the solar cell’s lifetime. “The strength of our method lies in its excellent reso­lution and great versa­tility”, says Vincent Lami, member of Vaynzof’s team. According to Vaynzof, their work solves a key problem in the field of organic photo­voltaics. “Without mapping the energetic land­scapes, it is difficult to understand how and why devices lose energy in the process of converting light into elec­tricity. Now we have a spectro­scopic method that allows us to develop new gene­rations of solar cells with reduced energy losses and improved per­formance”, emphasises the scientist, who heads the Organic Electronics research group at the Kirchhoff Institute for Physics. (Source: U. Heidelberg)

Reference: V. Lami et al.: Visualizing the Vertical Energetic Landscape in Organic Photovoltaics, Joule, online 9. Juli 2019; DOI: 10.1016/j.joule.2019.06.018

Link: Physical Principles of Organic and Hybrid Photovoltaics (Y. Vaynzof), Centre for Advances Materials, University of Heidelberg, Heidelberg, Germany

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