Press Release: Optoelectronics Achieves Spin Control with Chiral Perovskites and III-V Semiconductors

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Research led by scientists at the U.S. Department of Energy’s (DOE) National Renewable Energy Laboratory (NREL) has produced advances that could enable a wider range of currently unimaginable optoelectronic devices.

Scientists whose previous innovations include switching on the perovskite layer that allowed the creation of a new type of polarized light-emitting diode (LED) that emits spin-controlled photons at room temperature without the use of magnetic fields or ferromagnetic contacts, have now taken this a step further by integrating a III-V optoelectronic semiconductor structure with a chiral halide perovskite semiconductor. This means that they have transformed an existing commercial LED into one that also controls electron spin. These results provide a path to transforming modern optoelectronics, a field that relies on the control of light and includes LEDs, solar cells, and telecommunications lasers, among other devices.

“Where this goes and where it ends is up to the imagination,” said Matthew Beard, a senior scientist at NREL and co-author of a recently published paper
Nature article, “Room-Temperature Spin Injection Through a Chiral Perovskite/III-V Interface.”

Beard also serves as director of the Center for Hybrid Organic Inorganic Semiconductors for Energy (CHOISE), an Energy Frontier Research Center funded by the Office of Science Basic Energy Sciences within DOE. The reported research was funded by CHOISE and drew on a broad range of scientific expertise from NREL, the Colorado School of Mines, the University of Utah, the University of Colorado Boulder, and the Universite de Lorraine in France.

CHOISE aims to understand the control of charge, spin and light interconversion using carefully designed chemical systems. In particular, the work focuses on controlling electron spin, which can be either “up” or “down.” Most current optoelectronic devices rely on the interconversion of charge and light. But spin is another property of electrons, and controlling spin can enable a wide range of new effects and functionalities. The researchers published a paper in 2021 describing how, using two different layers of perovskite, they were able to control spin, creating a filter that blocks electrons that “spin” in the wrong direction.

They hypothesized that advances in optoelectronics could be made if they could successfully combine two semiconductors, and they went ahead and did just that. The breakthroughs that were made, including eliminating the need for subzero temperatures, could be used to speed up data processing and reduce the amount of power needed.

“Most current technologies are based on controlling charge,” Beard said. “Most people just forget about electron spin, but spin is very important, and it’s also another parameter that you can control and use.”

Manipulating electron spin in a semiconductor previously required the use of ferromagnetic contacts under an applied magnetic field. Using chiral perovskites, the researchers were able to transform an LED into one that emits polarized light at room temperature and in the absence of a magnetic field. Chirality refers to the structure of a material that cannot be superimposed on its mirror image, such as a hand. For example, a “left-handed” oriented chiral system can allow electrons with “up” spins to be transported but block electrons with “down” spins, and vice versa. The electron spin is then converted into the “spin,” or polarization, of the emitted light. The degree of polarization, which measures the intensity of light polarized in one direction, was achieved at about 2.6% in previous studies. Adding a III-V semiconductor — which is made of materials from the third and fifth columns of the periodic table — increased the polarization to about 15%. The degree of polarization is a direct measure of the accumulation of spins in the LED.

“This work is particularly exciting to me because it combines spin functionality with a traditional LED platform,” said first author Matthew Hautzinger. “You can buy an LED analogous to the one we used for 14 cents, but with chiral perovskite, we’ve transformed an already robust (and well-understood) technology into a futuristic spin-control device.”

Other NREL researchers listed as co-authors include Steven Hayden, Jiselle Ye, Qi Jiang, Mickey Wilson, Alan Phillips, Yifan Dong, Emily Raulerson, Ian Leahy, Chun-Sheng Jiang, Jeffrey Blackburn, Joseph Luther, Katherine Jungjohann, Joseph Berry and Kirstin Alberi.

NREL is the U.S. Department of Energy’s primary national laboratory for research and development in renewable energy and energy efficiency. NREL is operated for DOE by Alliance for Sustainable Energy LLC.