Researchers Find Mixed Perovskites Improve Thermal Stability in Solar Cells

Poor conductivity has, until now, resulted in thermal degradation in cells

May 24, 2024

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Researchers have combined ortho-carborane with perovskite cells to improve thermal stability and retained 80% of their initial efficiencies.

A team of researchers from Qingdao University of Science and Technology (QUST) in China and Canada’s University of Toronto have focused on the thermal stability challenges in mixed tin (Sn)-lead (Pb) perovskite solar cells (PSCs).

Thermal stability is a critical issue posing a barrier to the widespread commercialization of PSCs, even as mixed Sn-Pb has emerged as a promising material for single and multi-junction solar cells.

The study, published recently in Nature Communications journal, focused on a novel thermal regulation strategy using ortho-carborane (o-CB), an electron-delocalized carbon-boron molecule known for its efficient heat transfer capability.

The incorporation of o-CB into perovskite layers aims to enhance thermal conductivity, reduce heat accumulation, and improve overall device performance and longevity.

The researchers mixed Sn-Pb perovskites, which were promising due to their ideal bandgap and potential to exceed the efficiency limits of single-junction solar cells.

They found that poor thermal conductivity of mixed Sn-Pb perovskites results in insufficient thermal transfer and heat accumulation within the absorber layer, leading to thermal degradation.

However, mixed Sn-Pb cells treated with o-CB showed enhanced thermal stability, retaining 80% of their initial power conversion efficiencies (PCEs) after aging at 85°C for 1080 hours.

Single-junction mixed Sn-Pb cells achieved a maximum PCE of 23.4%, while all-perovskite tandem cells reached over 27% efficiency.

The researchers also utilized infrared thermal imaging and software simulation to demonstrate the improved heat transfer in o-CB-treated perovskite films. This was because o-CB contributed to better perovskite crystallization, further enhancing thermal stability and reducing non-radiative recombination losses.

The researchers found that this offers a sustainable thermal regulation using o-CB that can significantly improve the performance and stability of mixed Sn-Pb PSCs, making them more viable for large-scale applications and commercialization.

Researchers from Swansea University in the UK have recently found that introducing compatible hole-transport materials between perovskite and carbon can significantly improve the performance of the cells.

This follows a month after researchers from the same university established an affordable and scalable carbon ink formula to manufacture perovskite solar cells.

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