Solar energy with an' ironclad future'

Date:
November 16, 2021
Source:
University of Basel
Summary:
Solar energy plays an important role in the fight against climate
change as a substitute for fossil fuels. Dye-sensitized solar
cells promise to be a low-cost supplement to the photovoltaic
systems we know today. Their key feature is the dye sensitizers
attached to their surface. Researchers continue to improve the
performance with sensitizers using iron -- a commonly available
and environmentally friendly metal.



FULL STORY ========================================================================== Solar energy plays an important role in the fight against climate
change as a substitute for fossil fuels. Dye-sensitized solar cells
promise to be a low- cost supplement to the photovoltaic systems we
know today. Their key feature is the dye sensitizers attached to their
surface. Researchers at the University of Basel continue to improve
the performance with sensitizers using iron -- a commonly available and environmentally friendly metal.


========================================================================== Sensitizers are intensely coloured compounds that absorb light and convert
its energy into electricity by releasing electrons and "injecting" them
into the semiconductor. So far, the sensitizers used in the dye-sensitized solar cells have either been relatively short-lived or demanded the use of
very rare and expensive metals. The holy grail of photovoltaic research
is therefore the development of sensitizers using iron -- a metal that
is both environmentally friendly and the most abundant transition metal
on our planet.

For many years, experts considered iron compounds to be unsuitable for
these applications because their excited state following light absorption
is too short-lived to be of use for energy production. This changed around seven years ago with the discovery of a new class of iron compounds with
what are known as N-heterocyclic carbenes (NHCs).

The research group headed by Professor Edwin Constable and Professor
Catherine Housecroft at the University of Basel's Department of Chemistry
has been working with these compounds for a number of years. The team led
by project leader Dr. Mariia Becker now reports on their results with
a sensitizer based on a new family of NHCs in the specialist journal
Dalton Transactions.

A bit of vinegar and grease "We knew that we had to develop materials that would stick to the surface of a semiconductor and whose character would simultaneously allow the arrangement of the functional light-absorbing components on the surface to be optimized," explains Becker.

The researchers used a two-pronged approach to these challenges:
firstly, they incorporated carboxylic acid groups (as found in vinegar)
into the iron compound in order to bind it to the semiconductor's
surface. Secondly, they made the compounds "greasy" by adding long carbon chains that made the surface layer more fluid and easier to anchor.

These dye-sensitized solar cell prototypes only achieved overall
efficiency of 1 percent, while today's commercially available solar
cells reach around 20 percent efficiency. "Nevertheless, the results
represent a milestone that will encourage further research into these
new materials," says Becker with conviction.

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


========================================================================== Journal Reference:
1. Mariia Becker, Vanessa Wyss, Catherine E. Housecroft, Edwin
C. Constable.

The influence of alkyl chains on the performance of DSCs employing
iron (ii) N-heterocyclic carbene sensitizers. Dalton Transactions,
2021; DOI: 10.1039/d1dt03252f ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2021/11/211116103118.htm

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