Technical / research - Page 16

Researchers from Northwestern University, University of Toronto, ShanghaiTech University, University of Victoria and Arizona State University have developed highly stable, highly efficient 0.05cm² perovskite solar cell with a PCE of 26.15%, certified by a National Renewable Energy Laboratory-accredited facility. The team said that the prior certified world record published in a scientific journal was 25.73%.

A 1.04 cm² device had a certified power conversion efficiency of 24.74%, also a record for its size. The best devices retained 95% of their initial PCE following 1,200 hours of continuous solar illumination at a temperature of 65 degrees.

Researchers at Linköping University, Nanjing University and NanjingTech have developed a multifunctional display that uses photo-responsive metal halide perovskite LEDs as pixels. The perovskite LED display can be simultaneously used as a touch screen, ambient light sensor and image sensor (including for fingerprint drawing) without integrating any additional sensors. The light-to-electricity conversion efficiency of the pixels also allow the display to act as a photovoltaic device that can charge the equipment.

Illustration of functions realized by the multifunctional display. Image from Nature Electronics

This is a step forward compared to current display screens, which are typically only used for information display, but can have a range of different sensors integrated into them for functions such as touch control, ambient light sensing and fingerprint sensing. According to the team, photo-responsive light-emitting diodes (LEDs), which can display information and respond to light excitation, could be used to develop future ultra-thin and large screen-to-body ratio screens. However, photo-response is difficult to achieve with conventional display technologies. 

Researchers from the University of Freiburg and Fraunhofer ISE recently put together a roadmap for the optical properties of perovskite/perovskite/silicon triple-junction cells. They investigated the optical properties of perovskite/perovskite/silicon triple-junction cells and found these devices may have a practical efficiency potential of 44.3% assuming idealized electrical parameters. These cells may also potentially achieve a fill factor of 90.1%.

The group of researchers developed a comprehensive optoelectrical simulation model for triple-junction solar cells based on subcells relying on perovskite, perovskite, and crystalline silicon, respectively. The model aims to define an efficiency roadmap for improving the optical properties of these solar cells within realistic boundary conditions.

Researchers at Shanghai Jiao Tong University, Shanghai University of Electric Power and Shandong Normal University have addressed the traditional trial-and-error method for preparing high-efficiency perovskite solar cells (PSCs) by introducing a goal-driven approach that integrates machine learning and data mining techniques to rapidly screen high-efficiency PSCs based on key features. 

By predicting high-efficiency PSCs and identifying the dominant factors affecting their performance, namely the perovskite bandgap and the total thickness of the electron transport layer (ETL), this research aims to provide valuable insights for optimizing preparation processes and advancing the development of high-efficiency PSCs, thus significantly contributing to the renewable energy sector.

This is a sponsored post by MBRAUN

In the quest for cleaner, more efficient energy sources, perovskite solar cells have proven to be a promising prospect. Their exceptional efficiency, low-cost production and versatility make them a promising candidate for revolutionizing the renewable energy. However, the road to mass adoption faces hurdles, one of which is the need for precise and efficient manufacturing processes. Here's where vacuum evaporation tools shine as indispensable assets in the production of perovskite solar cells.

Precision Engineering for Optimal Performance

At the heart of perovskite solar cell fabrication lies the deposition of thin films with utmost precision under highly controlled conditions. MBRAUN evaporation tools from the PEROvap series offer unparalleled control over the deposition process, ensuring the uniformity and consistency essential to maximize solar cell efficiency. Addressing the volatility of most used Perovskite materials PEROvap systems are designed to control the temperature of the chamber, the substrate holder, the sources and the quartz crystals precisely from -40°C up to room. This avoids unwanted re-evaporation of already deposited materials and stabilizes the overall evaporation process. By vaporizing the material under vacuum conditions and depositing it onto the substrate, PEROvaps also eliminate impurities and defects that could affect performance, resulting in high-quality perovskite films with superior optoelectronic properties.

Learn more about the vacuum coating solutions from MBRAUN

Researchers from China's Wuhan University and South China Normal University have developed a two-terminal (2T) monolithic all-perovskite tandem solar cell that uses a tin-lead (Sn-Pb) perovskite material for the top cell.

The team explained that mixed Sn-Pb perovskites have a narrow bandgap (NBG) of approximately 1.26 eV, which makes them ideal for efficient light harvesting and current-matching with wide bandgap (WBG) subcells in all-perovskite tandem cells.

Researchers from China's Xiamen University, Innovation Laboratory for Sciences and Technologies of Energy Materials of Fujian Province (IKKEM), Yang Ming Chiao Tung University and Hon Hai Research Institute have reported a self-polarizing RGB device utilizing semipolar micro-LEDs and perovskite-in-polymer films aimed at improving backlight applications.

Structure of an LCD based on semipolar blue μLEDs excite anisotropic perovskite NCs as backlight. Image from Opto-Electronic Advances

In backlighting systems for LCDs, conventional red, green, and blue (RGB) light sources that lack polarization properties can result in a significant optical loss of up to 50% when passing through a polarizer. To address this inefficiency and optimize energy utilization, the scientists developed a high-performance device designed for RGB polarized emissions. The device uses an array of semipolar blue µLEDs with inherent polarization capabilities, coupled with mechanically stretched films of green-emitting CsPbBr₃ nanorods and red-emitting CsPbI₃-Cs₄PbI₆ hybrid nanocrystals. 

Researchers at the University of Sydney, Microsolar, University of New South Wales and MiaSolé Hi-Tech Corp. have reported a monolithic perovskite–CIGS tandem solar cell on a flexible conductive steel substrate with an efficiency of 18.1%, the highest for a flexible perovskite–CIGS tandem to date, representing an important step toward flexible perovskite-based tandem photovoltaics.

The advantage of the flexible and conductive steel substrate is that the steel itself can act as both a substrate and an electrode for either large-area-monolithic-panel or smaller-area-singular single-junction or multi-junction cell fabrication.

Researchers at China's Tsinghua University, Zurich University of Applied Sciences and University of Ferrara have developed a perovskite solar cell with a new hole transport material that promises enhanced efficiency and stability while also ensuring a scalable fabrication technique.

The team explained that the new organic hole-transporting material, named T2, offers a performance advantage over conventional materials like spiro-OMeTAD as its characteristics, including unique electronic, structural, and chemical properties, synergistically enhance the efficiency of hole extraction and significantly reduce charge recombination at the interface with the perovskite layer.

Researchers at the University of Potsdam, Humboldt-University of Berlin, University of Wuppertal, Swansea University, University of Oxford, East China University of Science and Technology, Friedrich-Alexander-University Erlangen-Nürnberg and HZB have shown that ion-induced field screening is a dominant factor in the operational stability of perovskite solar cells (PSCS). 

The rather poor perovskite stability is usually attributed to electronic defects, electrode oxidation, the ionic nature of the perovskite, or chemical decomposition under moisture and oxygen. Understanding the underlying degradation mechanism is crucial to enable targeted improvements. "In our article, we demonstrate that an increasing concentration of defects in the cells is apparently not a decisive factor for degradation," says Martin Stolterfoht, former leader of the Heisenberg junior research group PotsdamPero at the University of Potsdam and now professor at the Chinese University of Hong Kong.