Technical / research - Page 51

KAUST researchers have shared a detailed view of how electrical charges behave inside perovskites, which could guide efforts to improve the performance of next-generation solar cells based on these materials.

When light hits a perovskite, it excites negatively charged electrons and leaves behind positively-charged 'holes' within the material's crystalline structure. These electrons and holes can then move through the perovskite to generate an electrical current. But the charge carriers could also recombine instead, which wastes the energy they carry.

A team of scientists, led by Mohammad Nazeeruddin at École polytechnique fédérale de Lausanne (EPFL), has found a way to address the scaling up challenges of perovskites. The scientists have developed an easy solvothermal method to produce single-crystalline titanium dioxide rhombohedral nanoparticles that can be used to build a perovskite film.

The new structure is said to feature a lower amount of lattice mismatches, referring to the "ladder-like" structure of the titanium dioxide nanoparticles. This translates into a lower number of defects, which ensures better electron flow throughout with lower power loss.

A research team, co-led by scientists from City University of Hong Kong (CityU) and Imperial College London, has developed highly efficient and stable perovskite solar cells.

Among the different types of perovskite solar cells, those with an inverted design configuration have exhibited exceptional stability, making them good candidates to reach the lifetime of commercial silicon solar cells. However, perovskite materials include chemically reactive components, which can easily volatilize and degrade under high temperature and humidity, shortening the solar cells' operational lifetime. Also, there is still a need for strategy to enhance the efficiency of inverted perovskite solar cells up to 25% to rival that of silicon solar cells, while maintaining their stability.

A research group, led by Prof. XIAO Zhengguo from the University of Science and Technology of China (USTC) of the Chinese Academy of Sciences, has developed large-area and efficient sky-blue perovskite light-emitting diodes (PeLEDs) by blade-coating supersaturated perovskite solution.

Metal halide PeLEDs can achieve high luminance at low voltage due to their high electrical conductivity, making them ideal for the next generation of energy-saving lighting. Blue/sky-blue PeLEDs are essential for white lighting, but the EQE of blue light is relatively low since the crystallization process of such perovskite films is difficult to control, which results in poor film quality.

Researchers from the University of Toronto and their international collaborators have leveraged quantum mechanics to optimize the active layer within an inverted perovskite solar cell.

"Perovskite crystals are made from a liquid ink and coated onto surfaces using technology that is already well-established in industry such as roll-to-roll printing," says Hao Chen, a post-doctoral researcher in Sargent's lab and one of four co-lead authors of a new paper published in Nature Photonics. "Because of this, perovskite solar cells have the potential to be mass produced at much lower energy cost than silicon. The challenge is that right now perovskite solar cells lag traditional silicon cells in stability. In this study, we aimed to close that gap."

Researchers from Soochow University, Xi'an Jiaotong-Liverpool University and Egypt's National Research Centre have developed a novel approach for making an all-weather solar cell that is triggered by both sunlight and falling raindrops.

They designed the solar cell by integrating a triboelectric nanogenerator (TENG) and perovskite solar cells to harvest raindrop energy and solar energy efficiently to provide a distributed energy source.

Researchers from North Carolina State University and their collaborators have reported room-temperature superfluorescence in hybrid perovskite thin films and explained its origin.

The team has shown that the semiconducting perovskites that exhibit superfluorescence at room temperature do so due to built-in thermal "shock absorbers" which protect dipoles within the material from thermal interference.

A team of researchers from Pohang University of Science and Technology, University of Electronic Science and Technology of China and Sungkyunkwan University has improved the performance of a p-type semiconductor transistor, using inorganic metal halide perovskite.

One of the biggest advantages of the new technology is that it enables solution-processed perovskite transistors to be simply printed as semiconductor-like circuits.

A research team, led by Professor Ivan Mora Ser from the Institute of Advanced Materials (INAM) of the Universitat Jaume I of Castell, has improved the efficiency and durability of tin perovskite solar cells. The cells presented in the recent study exceeded 1,300 hours of operational stability, thanks to the incorporation of additives in the preparation of the devices.

Tin-based halide perovskites are being studied as potential candidates for lead-free perovskite solar cells. In the case of tin, an efficiency of more than 14% has been achieved so far, but it has major stability problems. This new work has introduced a combination of dipropylammonium iodide and sodium borohydride, two additives that have made it possible to prepare devices with PCEs of more than 10%, which boast greater stability and have maintained 96% of the initial PCE after 1,300 hours under solar illumination in a nitrogen atmosphere.

Researchers from North Carolina State University and the University at Buffalo have developed a 'self-driving lab' that uses artificial intelligence (AI) and fluidic systems to advance the understanding of metal halide perovskite (MHP) nanocrystals. This self-driving lab can also be used to investigate other semiconductor and metallic nanomaterials.

'We've created a self-driving laboratory that can be used to advance both fundamental nanoscience and applied engineering,' says Milad Abolhasani, corresponding author of a paper on the work and an associate professor of chemical and bimolecular engineering at NC State.