picture:
Assistant Professor HOU Yi (right) and Dr LIU Shunchang (left) from the National University of Singapore (NUS) developed new three-junction perovskite/Si tandem solar cells using advanced technologies and equipment at the Solar Energy Research Institute of Singapore. at NUS. These tandem solar cells have an impressive certified world record power conversion efficiency of 27.1 percent per 1 sq cm of active area.
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Credit: National University of Singapore
Scientists at the National University of Singapore (NUS) have developed a new triple-junction perovskite/Si tandem solar cell that can achieve a certified world-record power conversion efficiency of 27.1 percent per 1 sq cm of solar absorption area. Best performing triple junction perovskite/Si tandem solar cell ever. To achieve this, the team developed a new stable and energy-efficient cyanate-integrated perovskite solar cell.
Solar cells can be made in more than two layers and stacked to create multi-junction solar cells to increase efficiency. Each layer is made of different photovoltaic materials and absorbs solar energy in a different range. However, existing multi-junction solar cell technologies present many problems, such as energy loss, which leads to low voltage and instability during device operation.
To overcome these challenges, Associate Professor Hou Yi led a team of scientists from the NUS College of Design and Engineering (CDE) and the 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 an advanced three-junction perovskite/Si tandem solar cell that outperforms other similar multi-junction solar cells. Asst Prof Hou is a Presidential Young Professor in the Department of Chemical and Biomolecular Engineering at CDE, as well as a Group Leader at SERIS, a university-level research institute at NUS.
“Interestingly, after 15 years of research in the field of perovskite-based solar cells, this work is the first experimental evidence for incorporating cyanide into perovskites to increase structure stability and improve energy conversion efficiency,” said Assoc. Hou.
The experimental process that led to this groundbreaking discovery was published in the journal Nature on March 4, 2024.
Production of energy-saving solar cell technology
The interactions between the components of the perovskite structure determine the energy range it can reach. Adjusting the ratio of these components or finding a direct substitute can help change the energy range of the perovskite. However, previous research has yet to produce a perovskite recipe with an ultra-wide energy range and high efficiency.
In this recently published work, the NUS team experimented with cyanate, a new pseudohalide, as a replacement for bromide, an ion from the halide group commonly used in perovskites. Dr Liu Shunchang, a researcher in Asst Prof Hou’s team, used various analytical methods to confirm the successful integration of cyanate into the perovskite structure and developed a cyanate-integrated perovskite solar cell.
Further analysis of the new perovskite’s atomic structure provided, for the first time, experimental evidence that the incorporation of cyanate helps to stabilize its structure and create key interactions within the perovskite, demonstrating how it can replace halides in perovskite-based solar cells.
When evaluating the performance, the NUS scientists found that the cyanate-doped perovskite solar cells could achieve a higher voltage of 1,422 volts compared to 1,357 volts for conventional perovskite solar cells, significantly reducing energy loss.
The researchers also tested the newly developed perovskite solar cell by operating it continuously at maximum power for 300 hours under controlled conditions. After the test period, the solar cell remained stable and operated at more than 96 percent capacity.
Encouraged by the impressive performance of cyanate-integrated perovskite solar cells, the NUS team took their groundbreaking discovery to the next step by using it to assemble a triple-junction perovskite/Si tandem solar cell. The researchers assembled a perovskite solar cell and a silicon solar cell to create a two-junction half-cell, which provided an ideal base for adding a cyanate-integrated perovskite solar cell.
The researchers demonstrated that despite the complexity of the triple junction perovskite/Si tandem solar cell structure after assembly, it remained stable and achieved a certified world record efficiency of 27.1 percent from an accredited independent photovoltaic calibration laboratory.
“Collectively, these advances offer fundamental insights into reducing energy loss in perovskite solar cells and set a new course for the future development of perovskite-based triple-junction solar technology,” Associate Professor Howe said.
Next steps
The theoretical efficiency of triple-junction perovskite/Si tandem solar cells exceeds 50 percent, offering significant potential for further improvements, especially in applications where installation space is limited.
In the future, the NUS team aims to upgrade this technology to larger modules without compromising efficiency and stability. Future research will focus on innovations in the interfaces and composition of the perovskite – key areas identified by the team to further develop this technology.
Article Title
Cyanate triple-junction solar cells in ultra-wideband perovskites
Publication date of the article
March 4, 2024
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