Record 27.1% efficiency for three layer perovskite solar cell

Record 27.1% efficiency for three layer perovskite solar cell

Technology News |
By Nick Flaherty

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Researchers in Singapore have developed a new three layer, triple junction tandem solar cell that gives a record efficiency.

The team at Scientists from the National University of Singapore (NUS) have developed the tandem cell with two layers of perovskite on top of a silicon solar cell with conversion efficiency of 27.1 per cent across a solar energy absorption area of 1 cm2.

This represents the best-performing triple-junction tandem solar cell so far on the way to 50% conversion efficiency with triple layer cells.

The cell used a cyanate anion to achieve a higher voltage of 1.422 volts compared to 1.357 volts for conventional perovskite solar cells, with a significant reduction in energy loss.

Solar cells can be fabricated in more than two layers and assembled to form multi-junction solar cells to increase efficiency. Each layer is made of different photovoltaic materials and absorbs solar energy within a different range. However, current multi-junction solar cell technologies pose many issues, such as energy loss which leads to low voltage and instability of the device during operation.

To overcome these challenges, Assistant Professor Hou Yi led a team of scientists from NUS College of Design and Engineering (CDE) and Solar Energy Research Institute of Singapore (SERIS) to demonstrate, for the first time, the successful integration of cyanate into a perovskite solar cell to develop the triple-junction cell.

“Remarkably, after 15 years of ongoing research in the field of perovskite-based solar cells, this work constitutes the first experimental evidence for the inclusion of cyanate into perovskites to boost the stability of its structure and improve power conversion efficiency,” said Asst Prof Hou.

The interactions between the components of the perovskite structure determine the energy range that it can reach. Adjusting the proportion of these components or finding a direct substitute can help modify the perovskite’s energy range. However, prior research has yet to produce a perovskite recipe with an ultrawide energy range and high efficiency.

The team experimented on cyanate, a novel pseudohalide, as a substitute for bromide – an ion from the halide group that is commonly used in perovskites. Further analysis of the new perovskite’s atomic structure provided – for the first time – experimental evidence that incorporating cyanate helped to stabilise its structure and form key interactions within the perovskite, demonstrating how it is a viable substitute for halides in perovskite-based solar cells.

The researchers also tested the cell by continuously operating it at maximum power for 300 hours under controlled conditions as perovskites suffer from a shorter lifetime. After the test period, the solar cell remained stable and functioned above 96 per cent capacity.

The cyanate was then used in a triple-junction perovskite/Si tandem solar cell. The researchers stacked a perovskite solar cell on a silicon solar cell to create a dual-junction half-cell, providing a base for the attachment of the cyanate-integrated perovskite solar cell.

This showed a certified world-record efficiency of 27.1% from an accredited independent photovoltaic calibration laboratory.

“Collectively, these advancements offer ground-breaking insights into mitigating energy loss in perovskite solar cells and set a new course for the further development of perovskite-based triple junction solar technology,” said Asst Prof Hou.

The theoretical efficiency of triple-junction solar cells exceeds 50 per cent, presenting significant potential for further enhancements, especially in applications where installation space is limited.

Going forward, the NUS team aims to upscale this technology to larger modules without compromising efficiency and stability. Future research will focus on innovations at the interfaces and composition of perovskite – these are key areas identified by the team to further advance this technology.



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