Self-healing nanomaterials usable in solar panels and other electronic
devices

Date:
January 3, 2022
Source:
Technion-Israel Institute of Technology
Summary:
The field of self-repairing materials is rapidly expanding, and
what used to be science fiction might soon become reality, thanks
to scientists who developed eco-friendly nanocrystal semiconductors
capable of self- healing. Their findings describe the process,
in which a group of materials called double perovskites display
self-healing properties after being damaged by the radiation of
an electron beam.



FULL STORY ==========================================================================
From the Terminator to Spiderman's suit, self-repairing robots and devices abound in sci-fi movies. In reality, though, wear and tear reduce the effectiveness of electronic devices until they need to be replaced. What
is the cracked screen of your mobile phone healing itself overnight,
or the solar panels providing energy to satellites continually repairing
the damage caused by micro-meteorites?

==========================================================================
The field of self-repairing materials is rapidly expanding, and what used
to be science fiction might soon become reality, thanks to Technion --
Israel Institute of Technology scientists who developed eco-friendly nanocrystal semiconductors capable of self-healing. Their findings,
recently published in Advanced Functional Materials, describe the
process, in which a group of materials called double perovskites
display self-healing properties after being damaged by the radiation
of an electron beam. The perovskites, first discovered in 1839, have
recently garnered scientists' attention due to unique electro- optical characteristics that make them highly efficient in energy conversion,
despite inexpensive production. A special effort has been put into the
use of lead-based perovskites in highly efficient solar cells.

The Technion research group of Professor Yehonadav Bekenstein from
the Faculty of Material Sciences and Engineering and the Solid-State
Institute at the Technion is searching for green alternatives to the
toxic lead and engineering lead-free perovskites. The team specializes
in the synthesis of nano-scale crystals of new materials. By controlling
the crystals' composition, shape, and size, they change the material's
physical properties.

Nanocrystals are the smallest material particles that remain naturally
stable.

Their size makes certain properties more pronounced and enables research approaches that would be impossible on larger crystals, such as imaging
using electron microscopy to see how atoms in the materials move. This
was, in fact, the method that enabled the discovery of self-repair in
the lead-free perovskites.

The perovskite nanoparticles were produced in Prof. Bekenstein's lab using
a short, simple process that involves heating the material to 100DEGC for
a few minutes. When Ph.D. students Sasha Khalfin and Noam Veber examined
the particles using a transmission electron microscope, they discovered
the exciting phenomenon. The high voltage electron beam used by this
type of microscope caused faults and holes in the nanocrystals. The
researchers were then able to explore how these holes interact with the material surrounding them and move and transform within it.

They saw that the holes moved freely within the nanocrystal, but avoided
its edges. The researchers developed a code that analyzed dozens of videos
made using the electron microscope to understand the movement dynamics
within the crystal. They found that holes formed on the surface of the nanoparticles, and then moved to energetically stable areas inside. The
reason for the holes' movement inwards was hypothesized to be organic
molecules coating the nanocrystals' surface. Once these organic molecules
were removed, the group discovered the crystal spontaneously ejected
the holes to the surface and out, returning to its original pristine
structure -- in other words, the crustal repaired itself.

This discovery is an important step towards understanding the processes
that enable perovskite nanoparticles to heal themselves, and paves the
way to their incorporation in solar panels and other electronic devices.

Prof. Yehonadav Bekenstein completed his degrees in Physics and Chemistry
at the Hebrew University of Jerusalem. Following a postdoctoral fellowship
at the University of California, Berkeley, he joined the Technion faculty
in 2018. He has received multiple awards, including the Ka"te and Franz
Wiener Prize (Excellent PhD Thesis Award), the Rothschild Fellowship for postdoctoral scholars, and the Alon Scholarship for the Integration of Outstanding Faculty.

In 2020 he was awarded the ERC Starting Grant for early-career scientists.

========================================================================== Story Source: Materials provided by
Technion-Israel_Institute_of_Technology. Note: Content may be edited
for style and length.


========================================================================== Journal Reference:
1. Sasha Khalfin, Noam Veber, Shaked Dror, Reut Shechter, Saar
Shaek, Shai
Levy, Yaron Kauffmann, Leonid Klinger, Eugen Rabkin, Yehonadav
Bekenstein. Self‐Healing of Crystal Voids in Double Perovskite
Nanocrystals Is Related to Surface Passivation. Advanced Functional
Materials, 2021; 2110421 DOI: 10.1002/adfm.202110421 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2022/01/220103104609.htm
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