Cheaper solar cells could be on the way thanks to new materials

Date:
April 21, 2022
Source:
Imperial College London
Summary:
New solar cell devices that are cheaper and easier to make could
soon make their way to market thanks to new materials.



FULL STORY ==========================================================================
New solar cell devices that are cheaper and easier to make could soon make their way to market thanks to materials made at Imperial College London.


========================================================================== Traditional solar cells are made from silicon, which has good efficiency
and stability, but is relatively expensive to make and can only be
manufactured in stiff panels.

Perovskite solar cells offer an intriguing alternative; they can
be printed from inks, making them low cost, high efficiency, thin,
lightweight and flexible. However, they have trailed behind silicon
solar cells in efficiency and, importantly, stability, breaking down
under normal environmental conditions.

New metal-containing materials called ferrocenes could help with these problems. Researchers from City University of Hong Kong (CityU) have added Imperial-made ferrocenes into perovskite solar cells, vastly improving
their efficiency and stability. The results are published today in the
journal Science.

Co-lead author Professor Nicholas Long, from the Department of Chemistry
at Imperial, said: "Silicon cells are efficient but expensive, and we
urgently need new solar energy devices to accelerate the transition to renewable energy.

Stable and efficient perovskite cells could ultimately allow solar energy
to be used in more applications -- from powering the developing world
to charging a new generation of wearable devices.

"Our collaboration with colleagues in Hong Kong was beautifully
serendipitous, arising after I gave a talk about new ferrocene compounds
and met Dr Zonglong Zhu from CityU, who asked me to send over some
samples. Within a few months, the CityU team told us the results were
exciting, and asked us to send more samples, beginning a research program
that has resulted in perovskite devices that are both more efficient
and more stable." The power of ferrocenes


========================================================================== Perovskite forms the 'light-harvesting' layer of solar cell
devices. However, these devices have been less efficient at converting
solar energy into electricity than silicon-based solar cells, primarily
because the electrons are less 'mobile' -- they are less able to move
from the harvesting layer to the electricity conversion layers.

Ferrocenes are compounds with iron at their centre, surrounded by
sandwiching rings of carbon. The unique structure of ferrocene was
first recognised by Imperial's own Nobel Prize-winner Professor Geoffrey Wilkinson in 1952, and ferrocenes are still being researched around the
world today for their unique properties.

One property their structure gives them is excellent electron richness,
which in this case allows electrons to move more easily from the
perovskite layer to subsequent layers, improving the efficiency of
converting solar energy to electricity.

Tests performed by the team CityU and in commercial labs show that the efficiency of perovskite devices with an added ferrocene layer can reach
25%, approaching the efficiency of traditional silicon cells.

Two birds with one stone But this isn't the only problem the
ferrocene-based materials solved. The team at Imperial have been
experimenting with attaching different chemical groups to the carbon
rings of ferrocene, and after sending the Hong Kong team several versions
of these, made by PhD student Stephanie Sheppard, the collaborators
discovered a version that significantly improves the attachment of the perovskite layers to the rest of the device.



==========================================================================
This added attachment power improved the stability of the devices,
meaning they maintained more than 98% of their initial efficiency after continuously operating at maximum power for 1,500 hours. The efficiency
and stability gained thanks to the addition of a ferrocene layer brings
these perovskite devices close to current international standards for traditional silicon cells.

Lead researcher Dr Zonglong Zhu from CityU said: "We are the first team
to successfully boost the inverted perovskite solar cell to a record-high efficiency of 25% and pass the stability test set by the International Electrotechnical Commission." The team have patented their design and
hope to licence it, eventually bringing their perovskite devices to the
market. In the meantime, they are experimenting with different ferrocene designs to further improve the performance and stability of the devices.


========================================================================== Story Source: Materials provided by Imperial_College_London. Original
written by Hayley Dunning. Note: Content may be edited for style and
length.


========================================================================== Related Multimedia:
* The_solar_cell_with_the_ferrocene_layer_highlighted ========================================================================== Journal Reference:
1. Zhen Li, Bo Li, Xin Wu, Stephanie A. Sheppard, Shoufeng Zhang,
Danpeng
Gao, Nicholas J. Long, Zonglong Zhu. Organometallic-functionalized
interfaces for highly efficient inverted perovskite solar
cells. Science, 2022; 376 (6591): 416 DOI: 10.1126/science.abm8566 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2022/04/220421141545.htm

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