Technical / research - Page 41

Researchers from South Korea's Sungkyunkwan University (SKKU) have found that molybdenum ditelluride could increase carrier generation in perovskite solar cells.

They simulated a tandem solar cell with two absorbers based on methylammonium lead triiodide (CH₃NH₃PbI₃) – a perovskite with high photoluminescence quantum yield – and molybdenum ditelluride (MoTe₂), which is known for being naturally p-doped, with cascaded bandgaps to absorb a wider solar spectrum. The team determined that its efficiency could exceed 20%.

An international research group, led by Dr. Yang Bin from the Dalian Institute of Chemical Physics (DICP) of the Chinese Academy of Sciences (CAS), has developed cadmium (Cd)-based perovskite single crystals with long afterglow and high luminous quantum yield, and investigated its afterglow luminescence dynamics mechanism.

Afterglow materials have the ability to store multiple radiations such as visible photons, ultraviolet rays, and X-rays. They are widely used in display, biological imaging, anti-counterfeiting technology, and data storage. However, traditional all-inorganic phosphors, such as oxide, sulfide, and nitride-based afterglow materials, have high lattice energy and usually need to be produced by high-temperature processing (>1000°C), which brings considerable energy consumption and safety risks to production and preparation.

Researchers at the Indian Institute of Technology Mandi, National Institute of Solar Energy (NISE) and University of North Texas have reported perovskite-based solar technology that can generate power when irradiated with light produced in household light sources like LED or CFL.

The results of this research could support IoT technology, which is being increasingly used in mobile phones, smart homes, and other applications that require various kinds of real-time data. These IoT devices are required to run independently without relying on electrical grids for power supply; primary and secondary batteries are currently used to power such devices. All batteries, irrespective of their kind, have a finite lifespan and are neither cost-effective nor eco-friendly.

Researchers from the Indian Institute of Technology (IIT) Jodhpur, India have developed a series of perovskite-based catalysts capable of efficiently producing hydrogen under ambient conditions. The end application of this research could be in the automotive and energy sectors, according to the statement issued by IIT Jodhpur. The developed catalysts are lanthanides-based perovskite nanocomposite materials for artificial photosynthesis. In the patented method, the researchers have used natural sunlight to convert water into hydrogen and oxygen, using a recyclable catalyst based on low-cost, simple transition metal.

The research team screened over 100 catalyst combinations to develop five sets of catalysts that gave high hydrogen production under sunlight. The catalysts work for wastewater, saline water and brackish water. They are recyclable and can be used multiple times. Lanthanide-based catalytic systems gave the best results and were found effective in continuous pure hydrogen production for 7.5 hours.

One of the main advantages of halide perovskites is their availability and ease of production. They are also characterized by the stable bound state of an electron and an electron hole that makes up an exciton. By connecting an exciton to light in a photonic crystal plate, researchers from Russia's ITMO University and the UK's University of Sheffield were able to reach record optical nonlinearity values, which makes the plates a promising tool for controlling optical signals and, in the future, can render them useful in optical computers. 

Condensed matter physics describes, among other things, exciton-polaritons, which are special states in materials caused by a strong connection between light and matter, a photon and an exciton. Excitons are positively charged quasiparticles that result from a bound state of electrons and electron holes; these particles can freely move in a semiconductor. When the bound electron and electron hole “fall” onto each other, the exciton annihilates, emitting a photon with the exciton’s resonance energy (frequency).

Researchers from The University of Tokyo and Yamagata University have addressed the difficulty in creating blue quantum dots by developing a unique self-organizing approach for producing lead bromide perovskite quantum dots. The research also incorporates cutting-edge imaging technology to characterize these novel blue quantum dots.

Quantum dots (QDs) are used in optoelectronic devices and quantum computing, among other things, and are referred to as "artificial atoms" due to their confined and distinct electronic properties. Quantum dots have characteristics that fall in between those of bulk semiconductors and individual atoms and molecules. Their photoelectric qualities vary depending on their size and shape. Quantum dots (QDs) are considered attractive materials for the emissive constituent of light-emitting diodes (LEDs) due to their high color intensity in a small spectral region, facile color tunability, and notable stability. Moreover, QD-based materials exhibit refined colors, longer lifetimes, reduced production costs, and lower energy requirements compared to typical luminescent materials used in organic light-emitting diodes (OLEDs).

In June 2021, Tokyo Chemical Industry Company Limited (TCI) started offering new hole selective self-assembled monolayer (SAM) forming agents, 2PACz [Product Number: C3663], MeO-2PACz [D5798] and Me-4PACz [M3359] for high performance perovskite solar cells and OPVs. Now, TCI has expanded its range of SAMs by adding two new high-efficiency materials: Me-2PACz [M3477] and Br-2PACz [B6391].

The SAM materials enable efficient, versatile and stable p-i-n perovskite solar cell devices. These materials are useful for tandem solar cells as they grant conformal coverage on rough textures. In fact, a perovskite solar cell that uses the SAM hole transport layer can realize more than 20% efficiency without using dopants or additives. Perovskite-Silicon tandem solar cells that use Me-4PACz as a hole contact material realized 29.15% efficiency. Costs are lowered thanks to extremely low material consumption, and the processing is very simple and scalable.

Researchers from Northwestern University, University of Toronto and the University of Toledo have developed an all-perovskite tandem solar cell with extremely high efficiency and "record-setting" voltage.

“Further improvements in the efficiency of solar cells are crucial for the ongoing decarbonization of our economy,” says U of T Engineering Professor Ted Sargent (ECE). “While silicon solar cells have undergone impressive advances in recent years, there are inherent limitations to their efficiency and cost, arising from material properties. Perovskite technology can overcome these limitations, but until now, it had performed below its full potential. Our latest study identifies a key reason for this and points a way forward.”

Researchers from the Department of Energy’s Ames National Laboratory and The University of Toledo have developed a new characterization tool that allowed them to gain unique insight into a perovskite material. Led by Ames' Jigang Wang, the team developed a microscope that uses terahertz waves to collect data on material samples. The team then used their microscope to explore Methylammonium Lead Iodide (MAPbI₃) perovskite.

Richard Kim, a scientist from Ames Lab, explained the two features that make the new scanning probe microscope unique. First, the microscope uses the terahertz range of electromagnetic frequencies to collect data on materials. This range is far below the visible light spectrum, falling between the infrared and microwave frequencies. Secondly, the terahertz light is shined through a sharp metallic tip that enhances the microscope’s capabilities toward nanometer length scales.

Researchers from the Technical University of Dresden, led by Prof. Yana Vaynzof, have demonstrated a new concept for the formation of a heterojunction for photovoltaics. The team took advantage of the fact that materials can often exist in different structural configurations, termed crystalline phases. This phenomenon, called polymorphism, means that the same material can exhibit different properties, depending on the specific arrangements of atoms and molecules in its structure.

By interfacing two such phases of the same material, Prof Vaynzof and her team demonstrated for the first time the formation of a phase heterojunction solar cells. Specifically, the researchers chose a caesium lead iodide perovskite – a highly efficient solar cell absorber material – in the beta and gamma phases to realise their new concept.