Researchers have demonstrated that certain molecules previously viewed as potentially detrimental to copper electrolyte performance are crucial to suppressing recombination losses and maximizing efficiency when harnessed correctly

Date:
September 3, 2020
Source:
ARC Centre of Excellence in Exciton Science
Summary:
Dye-sensitised solar cells could perform better thanks to improved
understanding of additives in optimizing electrolytes. Researchers
have determined that the molecules 4-tert-butylpyridine (tBP)
and 1-methyl- benzimidazole (NMBI) can play an integral role in
suppressing recombination losses and maximizing efficiency.



FULL STORY ========================================================================== Dye-sensitised solar cells used in low-light conditions could perform
more consistently thanks to improved understanding of the role additives
play in optimising electrolytes.


========================================================================== Laptops and mobile phones, among other devices, could be charged or
powered indoors, away from direct sunlight, using dye-sensitised solar
cells (DSCs), which have achieved efficiencies of up to 34% at 1000 lux
from a fluorescent lamp.

Copper-based electrolytes containing various combinations of additives
have been used to achieve these efficiencies, with varying results
to date.

Interaction of these additives with the copper species in the electrolyte
has been a concern over the last few years, and progress has been
undermined by a lack of understanding about the true effect of the
different additives.

Now, research funded by the Australian Centre for Advanced Photovoltaics
(ACAP) and supported by the ARC Centre of Excellence in Exciton
Science, has demonstrated the crucial importance of the molecules 4-tert-butylpyridine (tBP) and 1-methyl-benzimidazole (NMBI) as optimal additives for maximising the performance of the copper redox mediators.

The results have been published in the journal Advanced Energy Materials.



========================================================================== X-ray diffraction analysis, absorption, and nuclear magnetic resonance spectroscopy were used to find the combination of additives that most efficiently suppresses recombination losses, resulting in improved solar
cell performance.

Joint first author Dr Sebastian Fu"rer of Monash University and Exciton
Science said: "Researchers were previously a bit worried because tBP can interact with copper complexes and everyone said, 'let's try to avoid
it'. People thought this is detrimental to the solar cell performance
but we had a closer look at this.

"We actually found that it's really important to keep it in because it
reduces one of the main loss mechanisms.

"That's a really exciting find. So, from here onwards, people need to
think of that interaction in order to have high efficiencies for these devices." According to Sebastian, employing the correct additive in
new copper redox mediators is now likely to become standard in future
efforts to improve DSC performance.



==========================================================================
"You can't leave it out, because the solar cell goes from 9% efficiency
to less than 1%. It's really a huge difference," he said.

"Instead of trying to avoid that interaction, for the future,
researchers will need to make sure this interaction happens but only in a beneficial way. We've looked at all the different parts and solved a big question. The results are very conclusive." Joint first author Dr Rebecca Milhuisen, also of Monash University, added: "Our findings identify
crucial performance-deterring loss mechanisms and are a step further
towards the development of low-cost charge transporting materials for
next generation solar cells." Senior author Professor Udo Bach of Monash University believes the findings will enable researchers to successfully
design and create a more efficient next generation of materials.

"Printable low-cost dye-sensitized solar cells have seen a considerable efficiency boost over the past years," he said.

"This increase has been mainly fuelled by the incorporation of
new copper-based compounds that help with the separation of the
photo-generated charges.

"In our paper we reveal previously unknown details about the interplay
of these compounds with other additives in the cell which are the key
to their outstanding performance.

"Equipped with this new knowledge, we can now design the next generation
of copper-based charge transport materials which should be even more efficient."

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


========================================================================== Journal Reference:
1. Sebastian O. Fu"rer, Rebecca A. Milhuisen, Muhammad K. Kashif,
Sonia R.

Raga, Shravan S. Acharya, Craig Forsyth, Maning Liu, Laszlo
Frazer, Noel W. Duffy, C. Andre' Ohlin, Alison M. Funston,
Yasuhiro Tachibana, Udo Bach. The Performance‐Determining
Role of Lewis Bases in Dye‐Sensitized Solar Cells Employing
Copper‐Bisphenanthroline Redox Mediators. Advanced Energy
Materials, 2020; 2002067 DOI: 10.1002/ aenm.202002067 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/09/200903095609.htm

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