Technical / research - Page 30

Researchers from China's Zhejiang University and South China University of Technology have developed transparent glassy composites based on lead-free anti-perovskites in a novel approach that could revolutionize X-ray imaging.

There is a high demand for high-resolution and ultrastable X-ray imaging methods in various fields, like material inspection, medical diagnostics, astronomical discovery, and scientific research. This demand has ignited a vigorous pursuit of innovative X-ray-responsive materials that must possess exceptional qualities such as high X-ray attenuation, efficient scintillation, rapid light decay, and robust durability. Among them, lead-halide-based perovskites have emerged as a compelling contender due to their remarkable luminescence efficiency, superior X-ray attenuation capabilities, and short fluorescence lifetimes. However, their application in the scintillation field is hindered by the toxicity of heavy metal lead (Pb), low photon yield caused by self-absorption effects, and poor X-ray irradiation stability.

Researchers at the RIKEN Center for Emergent Matter Science (CEMS) in Japan have reported a simple and affordable perovskite-based way to store ammonia, an important chemical in a range of industries. 

Ammonia is widely used across industries ranging from textiles to pharmaceuticals and is an important component in the manufacture of fertilizers. For its current use, ammonia is stored in pressure-resistant containers after liquefying it at temperatures of -27 Fahrenheit (-33 degrees Celsius). Alternate methods of storing ammonia in porous compounds have been explored. The storage and retrieval process can be achieved at room temperature, but the storage capacity of these compounds is limited. The research team, led by Masuki Kawamoto at RIKEN CEMS, has found that perovskites can also serve as an excellent medium for the storage and retrieval of ammonia.

Researchers from Thailand's Mahidol University, Chiang Mai University, the Center of Excellence for Innovation in Chemistry (PERCH-CIC) and the National Metal and Materials Technology Center (MTEC) have developed triple-cation perovskite solar cells for low-light applications using a manufacturing process based on antisolvent deposition and vacuum thermal annealing (VTA).

“VTA leads to compact, dense, and hard morphology while suppressing trap states at surfaces and grain boundaries, which are key culprits for exciton losses,” the team stated, emphasizing the importance of the second step to produce a high quality perovskite layer. “As indoor light intensity is at least 300 times lower than that of sunlight, dense and homogeneous perovskite formation enticed by vacuum thermal annealing is valuable.”

Researchers at MIT have developed a bottom-up approach for precise and scalable formation of perovskite nanocrystal arrays with deterministic control over size, number, and position. The new platform enables researchers to 'grow' halide perovskite nanocrystals with precise control over the location and size of each individual crystal, integrating them into nanoscale light-emitting diodes.

Halide perovskite materials have largely been implemented into thin-film or micron-sized device applications. Precisely integrating these materials at the nanoscale could open up even more remarkable applications, like on-chip light sources, photodetectors, and memristors. However, achieving this integration has remained challenging because this delicate material can be damaged by conventional fabrication and patterning techniques.

A research group, led by Professor Minoru Osada at the Institute for Materials and Systems for Sustainability (IMaSS), Nagoya University in Japan, in collaboration with NIMS, has used perovskite materials to develop a nanosheet device with the highest energy storage performance yet seen. 

Dielectric energy storage capacitors could be a promising alternative to current energy storage technologies like lithium-ion batteries. The basic structure of the capacitor is a sandwich-like film made of two metal electrodes separated by a solid dielectric film. Dielectrics are materials that store energy through a physical charge displacement mechanism called polarization. When an electric field is applied to the capacitor, the positive charges are attracted towards the negative electrode. The negative charges are attracted towards the positive electrode. Then, storing electrical energy depends on the polarization of the dielectric film by applying an external electric field. 

Printable planar carbon electrodes are emerging as a promising replacement for thermally evaporated metals as the rear contact for perovskite solar cells (PSCs). However, the power conversion efficiencies (PCEs) of the state-of-the-art carbon-electrode PSC (c-PSC) noticeably lag behind their metal-electrode counterparts. Recently, researchers from Friedrich-Alexander-Universität Erlangen-Nürnberg have proposed a hole-transporting bilayer (HTbL) configuration to improve the fill factor and the open-circuit voltage of carbon electrode PSCs (c-PSCs). 

The HTbL was prepared by sequentially blade coating two organic semiconductors between perovskite and carbon, with the outer HTL enhancing hole extraction to carbon, while the inner HTL mitigates perovskite surface recombination. Consequently, the fully printed c-PSCs with HTbL outperformed those with single HTL, and a stabilized champion PCE of 19.2% was achieved compared with that of 17.3%. 

The following is a sponsored post by MBRAUN

Germany-based inert gas leading solutions provider MBRAUN is offering a wide range of solutions for the perovskite industry, ranging from R&D systems to full-industrial solutions. One of the company’s customers, KAUST University in Saudi Arabia, recently announced a word record with the help of MBRAUN systems.

Erkan Aydin, Professor and Researcher Scientist at KAUST, says: “In two months' time, we've set a new world record for perovskite/silicon tandem solar cells - again! With our latest update, perovskite/silicon tandem solar cells have reached impressive 33.7% certified power conversion efficiency, surpassing our previous milestone of 33.2%. We hope that our new achievement will contribute to accelerating the green energy transition. The recent champion cell was certified at European Solar Test Installation (ESTI) Center.”

New efficiency world record, June 2023

Only in the beginning of April, researchers from the KAUST Photovoltaic Laboratory (KPV-Lab) at the KAUST Solar Center produced a perovskite/silicon tandem solar cell with a power conversion efficiency (PCE) of 33.2 %, topping the world record recently set by the Helmholtz-Zentrum Berlin (HZB).

Researchers from Northern Illinois University, National Renewable Energy Laboratory (NREL), Northwestern University and Argonne National Laboratory have reported a bilayer back electrode configuration consisting of an Ni-doped natural graphite layer with a fusible Bi-In alloy. This back electrode can be deposited in a vacuum-free approach and enables perovskite solar cells (PSCs) with a power conversion efficiency of 21.0%. These inexpensive materials and facile ambient fabrication techniques can help provide an appealing solution to low-cost PSC industrialization.

A thin layer of gold or silver can help improve the efficiency of perovskite solar cells, but the researchers have found a less expensive material that will enable commercialization of the technology without exorbitant cost.  “A layer of gold in a solar panel or even a layer of silver is probably too expensive,” said Kai Zhu, a senior scientist in the Chemistry and Nanoscience Center at the U.S. Department of Energy’s National Renewable Energy Laboratory (NREL). “It would make the solar panel not affordable for most people.”

Researchers at the National University of Singapore (NUS) and Solar Energy Research Institute of Singapore (SERIS) have announced achieving 24.35% efficiency for self-designed inverted perovskite solar cells on an active area of 1 cm² , saying it is an improvement over the previous record high of 23.7% on the same area.

To get to this 24.35% efficiency level, the team says it incorporated a novel interface material into perovskite cells that contributed a ‘range of advantageous attributes’. These include excellent optical, electrical and chemical properties that enhanced both their efficiency and longevity.

Researchers at Florida State University, the FAMU-FSU College of Engineering, the University of Colorado Boulder and Argonne National Laboratory have studied the effects of two stressors, heat and light, on the triplet generation process at the perovskite/rubrene interface. Following exposure to both stressors, local discrepancies across the upconversion device were discovered. This work emphasizes the challenges and continued potential for the integration of perovskite-sensitized upconversion (UC) into commercial photovoltaic devices. 

The first region showed changes to the morphology, and no detectable upconverted emission was observed. Through the combination of optical microscopy and spectroscopy, crystallization of the organic semiconductor layer, degradation of dibenzotetraphenylperiflanthene, and concurrent degradation of the perovskite sensitizer were found. These effects culminate in a reduction in both triplet generation and triplet–triplet annihilation. In the second region, no changes to the morphology were present and visible UC emission was observed following exposure to both stressors. To probe the triplet sensitization process at elevated temperatures, transient absorption spectroscopy was performed. The presence of the excited spin-triplet state of rubrene at 60 °C highlighted successful triplet generation even at elevated temperatures.