Technical / research - Page 62

Researchers from King Abdullah University of Science and Technology (KAUST) in Saudi Arabia, in collaboration with University of Toronto, the National University of Singapore and National Technical University of Athens, have designed monolithic tandem solar cell with power conversion efficiency of 27%, surpassing the previous best reported value of 22% in the same configuration.

The team explains that translating the high power conversion efficiencies of single-junction perovskite solar cells in their classic, non-inverted (n'i'p) architecture to efficient monolithic n'i'p perovskite/silicon tandem solar cells with high current densities has been a persistent challenge due to the lack of low-temperature processable, chemically-insoluble contact materials with appropriate polarity and sufficient optical transparency. To address this, they developed sputtered amorphous niobium oxide (a-NbOx) with ligand-bridged C60 as an efficient electron-selective contact, deposited on the textured-silicon bottom cell.

A team of researchers from Hong Kong University and the Korea Electrotechnology Research Institute (KERI) have used 3D printing to create nanoscale display pixels made of perovskite.

3D printing of perovskite nanopixels using a nanopipette. Different chemical compositions enable the fabrication of red (R), green (G), and blue (B) triple pixels. Image via KERI

Last year, the same group of scientists used liquid inks and direct ink writing to fabricate display pixels capable of emitting light. Now, turning their attention to perovskites, the researchers believe they can achieve even greater brightness levels and higher resolution displays using a similar deposition-based 3D printing technique.

Researchers from ITMO University, the Far Eastern Federal University (FEFU), the Image Processing Systems Institute of RAS, and Tokai University (Japan) have discovered a way to fashion perovskite microcrystals into desired shapes for further use in the production of lenses and other optoelectronic elements without loss of quality.

This research opens up new opportunities for the creation of micro-optical elements that could be used in microchips and other optoelectronic devices.

University of Cambridge and Cornell University Researchers have done 'cradle-to-grave' life cycle assessments of a variety of perovskite solar cell architectures, and found that substrates with conducting oxides and energy-intensive heating processes are the largest contributors to primary energy consumption, global warming potential and other types of impact.

The team therefore focus on these materials and processes when expanding to 'cradle-to-cradle' analyses with recycling as the end-of-life scenario. Their results revealed that recycling strategies can lead to a decrease of up to 72.6% in energy payback time and a reduction of 71.2% in greenhouse gas emission factor.

Researchers from EPFL, Universität Tübingen and University of Fribourg, led by Professor Michael Grätzel at EPFL's School of Basic Sciences, used a novel method with multimodal host-guest complexation to significantly improve the stability of perovskite solar cells while also reducing the release of lead into the environment. The strategy involves using a member of the crown ethers, a family of cyclic compounds whose ring-like atomic structure resembles a crown.

The researchers used the dibenzo-21-crown-7 in the fabrication of formamidinium lead iodide perovskite solar cells. They demonstrated the efficiency of this synergistic approach with cesium metal ions, for which the crown ether shows a strong affinity. Acting as a vehicle, the crown ether assembles at the perovskite film's interface and delivers the cesium ions into its interior.

Rice University scientists have created microscopic seeds for growing uniform 2D perovskite crystals that are both stable and highly efficient at harvesting electricity from sunlight. Rice's seeded growth method addresses both performance and production issues and could promote perovskite photovoltaic technology.

Chemical engineers from Rice's Brown School of Engineering describe how to make the seeds and use them to grow homogenous thin films of materials comprised of uniformly thick layers. In laboratory tests, photovoltaic devices made from the films proved both efficient and reliable, a previously problematic combination for devices made from either 3D or 2D perovskites.

Researchers from North Carolina State University have shown that a commonly studied perovskite can superfluoresce at temperatures that are practical to achieve and at timescales long enough to make it potentially useful in quantum computing applications. The team also found that superfluorescence may be a common characteristic for this entire class of materials.

Superfluorescence is an example of quantum phase transition ' when individual atoms within a material all move through the same phases in tandem, becoming a synchronized unit.

A research team led by Professor Jang-Sik Lee of Pohang University of Science and Technology (POSTECH) has developed a halide perovskite-based memory with ultra-fast switching speed.

Resistive switching memory is a promising contender for next-generation memory device due to its advantages of simple structure and low power consumption. Various materials have been previously studied for resistive switching memory. Among them, halide perovskites are receiving much attention for use in the memory because of low operation voltage and high on/off ratio. However, halide perovskite-based memory devices have limitations like slow switching speed which hinder their practical application in memory devices.

researchers at the Okinawa Institute of Science and Technology Graduate University (OIST), led by Professor Yabing Qi, have demonstrated that creating a raw material used for perovskite solar cells in a different way could be key to the success of these cells.

'There's a necessary crystalline powder in perovskites called FAPbI₃, which forms the perovskite's absorber layer,' explained one of the lead authors, Dr. Guoqing Tong, Postdoctoral Scholar at OIST. 'Previously, this layer was fabricated by combining two materials ' PbI₂ and FAI. The reaction that takes place produces FAPbI₃. But this method is far from perfect. There are often leftovers of one or both of the original materials, which can impede the efficiency of the solar cell.'

Researchers at the Dresden University of Technology (TUD) have announced the fabrication of a solar cell based on all-inorganic cesium-lead iodide (CsPbI₃) perovskite, which is also sometimes referred to as 'black perovskite'.

a) Schematic of the deposition procedure (b) device structure. Image from Advanced Energy Materials

TUD researcher Yana Vaynzof said that the choice of this specific material was motivated by the fact that it shows superior stability as compared to the commonly used organic-inorganic lead halide perovskites.