The need for clean energy has increased the use of solar cells across multiple sectors. However, conventional silicon solar cells have certain limitations and are expensive when compared to perovskite solar cells, which scientists see as a better alternative to the former.
These types of cells represent photovoltaic technology and offer higher efficiency compared to conventional cells. Perovskite solar cells also offer increased versatility in design and manufacturing.
Now, researchers in India have proposed bifacial electron transport layer (ETL)-free perovskite solar cells. These are claimed to offer power conversion efficiency of more than 27%.
Electron transport layer-free PSCs offer a flexible approach for harnessing energy
Published in the journal Next Energy , the study was conducted by researchers from Indian Institute of Technology and National Institute of Technology.
They claimed that the electron transport layer (ETL)-free PSCs offer a flexible approach for harnessing energy while adding a bifacial approach that can further improve the device performance .
Researchers optimized ETL-free bifacial PSCs via simulation by selecting the suitable front transparent electrode (FTE), hole transport layer (HTL), and rear transparent electrode (RTE).
Structure associated with a small conduction band offset holds potential for enhancing efficiency
“Our investigation reveals that a potential well-like structure, associated with a small conduction band offset (CBO) at the FTE/perovskite interface holds significant potential for enhancing the power conversion efficiency (PCE) of the device,” said researchers.
They claimed that upward shift in the valance band of hole transport layer promotes recombination and reduces the device performance.
The bandgap and electron affinity of the rear transparent electrode highly influence the band alignment at the hole transport layer and rear transparent electrode interface.
Tri-layer rear transparent electrode provides a better band alignment with hole transport layer
“The NiO/Ag/NiO (NAN) tri-layer rear transparent electrode provides a better band alignment with hole transport layer, and improves the charge transportation and, hence, the device performance,” added researchers.
“Moreover, the thickness of the interfacial defect layer at the FTE/perovskite and perovskite/HTL interfaces significantly impacts device performance.”
Researchers optimized ETL-free bifacial PSCs by using SCAPS-1D simulation package
In the study, researchers simulated and optimized ETL-free bifacial PSCs by using the SCAPS-1D simulation package.
They observed the effect of different front transparent electrode (FTE), hole transport layer (HTL), and rear transparent electrode on achieving an optimum device configuration.
Upon selecting a suitable front transparent electrode, researchers found that the lower value of CBO at the FTE/perovskite interface exhibits improved device performance owing to the potential-well-like structure.
Electron affinity of the rear transparent electrode plays crucial role
The electron affinity of the rear transparent electrode (RTE) is found to play a crucial role in the band alignment at the RTE/HTL interface and, hence, the device performance, according to researchers.
Built with layers of materials, either printed or coated from liquid inks or vacuum-deposited, perovskite solar cells are thin-film devices.
Built with layers of materials, either printed or coated from liquid inks or vacuum-deposited, perovskite solar cells are thin-film devices and can be tuned to respond to multiple colors in the solar spectrum by changing the material composition, and a variety of formulations have demonstrated high performance.
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