2022 Thayer Investiture

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Halide Perovskites—An emerging class of semiconductors for optoelectronic applications

Apr

19

Monday
3:30pm - 4:30pm EST

Videoconference

ZOOM LINK
Meeting ID: 953 5527 5056
Passcode: 904558

Halide perovskites are an exciting class of semiconductors that holds enormous promise for even cheaper and ubiquitous photovoltaics. These materials emerged merely a decade ago as an absorber in solar cells, but perovskite solar cell efficiencies already exceed most other thin-film technologies with lab efficiencies exceeding 25.5%. The underlying reason for the rapid rise of perovskite photovoltaics (PV) are the excellent semiconductor properties of halide perovskites despite being deposited via facile solution-based processing techniques—such as ink-jet printing. This means a future can be envisioned in which solar panels are printed like newspapers.

Beyond photovoltaics, halide perovskite semiconductors have also found use in photonic sources such as light-emitting diodes and lasers, and as wide-band detectors for example for X-rays. Aside from the outstanding conventional semiconductor characteristics, halide perovskites have additional unique properties such as wide tunability of their bandgap allowing for all-perovskite multijunction devices, and their radiation resistance making them particularly interesting for space applications.

Conversely, halide perovskites have some unique vulnerabilities including being partially water soluble, and containing highly reactive constituent materials. Therefore, it is critical to develop contact materials for devices which keep the perovskite contained and moisture out. Here, I will first discuss the use of composite materials based on single-walled carbon nanotubes as charge-selective contacts, why they work and how they can stabilize perovskite solar cells. Next, I will highlight the use of time-resolved microwave conductivity as a contactless characterization technique for elucidating the charge transfer between perovskites absorbers and charge-selective contacts, such as carbon nanotube networks. I will further discuss how this technique can be used to characterize the perovskite quality itself and determine important characteristics such as charge-carrier mobility or the trap density. Finally, I will explore the use of halide perovskites beyond PV, namely in neuromorphic computing where we have recently demonstrated that a junction between perovskite quantum dots and carbon nanotubes can act as a photonic synapse with energy consumption as low as biological systems.

The wide range of beneficial properties of halide perovskites make them attractive for a variety of applications, ranging from terrestrial and extraterrestrial largescale PV installations, to highly efficient light sources to new medical imaging devices. However, looking to the future many more optoelectronic uses are conceivable from artificial neural networks to complex photocatalytic systems to spintronics; while the research is still at its beginning, the future for halide perovskites is certainly bright.

About the Speaker(s)

Severin Habisreutinger
Staff Scientist, Chemistry & Nanoscience Center, NREL

After finishing his BS and MS in physics at the Ludwig-Maximilians University of Munich, Severin Habisreutinger pursued a PhD in condensed matter physics at University of Oxford, UK, under the guidance of Profs. Robin Nicholas and Henry Snaith. His graduate work was dedicated to improving the stability of halide perovskite solar cells by developing and integrating new charge selective contact materials. He received his doctorate in 2016, and was subsequently awarded the highly prestigious Director’s Fellowship at the National Renewable Energy Laboratory (NREL) in Golden, CO. There he continued to explore the use of halide perovskite materials in optoelectronic devices, with a particular focus on the interfaces in solar cells.

To more deeply investigate these materials, he has focused on the development and optimization of various synthetic routes, allowing him to work at the interface of fundamental science and industrial application. He specializes in the use of sophisticated spectroscopic techniques such as photoluminescence spectroscopy, time-resolved microwave conductivity and ultrafast transient absorption to probe the fundamental physics underlying the intriguing properties of these unique semiconductors. He is currently a staff scientist at NREL, where his work largely focuses on the transfer of halide perovskite photovoltaics from the lab to commercial use, and on the space-readiness of halide perovskite solar cells. To date, he has co-authored over 30 peer-reviewed publications in highly respected journals, and his work has resulted in three published or pending patents.

Contact

For more information, contact Ashley Parker at ashley.l.parker@dartmouth.edu.