Perovskite sensors - Page 5

KAUST researchers have developed an artificial electronic retina based on perovskite materials, that can "see" in a similar way to the human vision system and can recognize handwritten digits.

The team designed and fabricated an array of photoreceptors that detect the intensity of visible light via a change in electrical capacitance, mimicking the behavior of the eye's rod retina cells. When the array was connected to an electronic CMOS-sensing circuit and a spiking neural network (a single-layer network with 100 output neurons), it was able to recognize handwritten numbers with an accuracy of around 70%.

Researchers from Innovation Lab HySPRINT at Helmholtz-Zentrum Berlin (HZB) and Humboldt Universität zu Berlin (HU) have used an advanced inkjet printing technique to produce a large range of photodetector devices based on a hybrid perovskite semiconductor.

By mixing three inks, the researchers were able to precisely tune the semiconductor properties during the printing process. Inkjet printing is already an established fabrication method, allowing fast and cheap solution processing. Extending the inkjet capabilities from large area coating towards combinatorial material synthesis could open the door to new possibilities for the fabrication of different kinds of electronic components in a single printing step.

Researchers from TNO at Holst Centre, Solliance and TU/e have jointly developed a thin and flexible perovskite-based scanner for fingerprints.

Low-resolution image-sensor arrays have been demonstrated in the past, but the high-resolution, high pixel-count image sensors suitable for commercial applications have not yet been truly achieved. The thin and flexible scanner in this new work is based on metal-halide perovskites (MHPs). Gerwin Gelinck, Chief Technology Officer TNO at Holst Centre, elaborates on the new study: 'Perovskites are marvelous materials! For the first time we show that these materials are also very good for light imaging and sensing applications. When combined with display-like transistors, we made a scanner that can capture high-resolution color images as well as biometric fingerprinting'.

Researchers at the Dutch Organization for Applied Scientific Research and Eindhoven University of Technology in the Netherlands have recently used a solution-processed photodetector made of a metal halide perovskite to fabricate a thin and flexible scanner. This scanner can be used to scan both fingerprints and paper documents.

"Fabricating photodetectors with low dark currents and integrating them into high-resolution backplanes remains challenging," Albert J. J. M. van Breemen and his colleagues wrote in their paper. "Here, we show that solution-processed metal halide perovskite photodiodes on top of an amorphous indium gallium zinc oxide transistor backplane can be used to create a flexible image sensor that is ~100'μm thick and has a resolution of 508 pixels per inch."

Scientists at EPFL and their collaborators have developed a simple and low-cost perovskite-based device that detects neutrons. The perovskite materials used in the study are based on lead and bromine. Both contain single crystals of a compound called methylammonium lead tri-bromide.

The team first placed these crystals in the path of a neutron source. The neutrons, hitting the crystals, penetrate the nucleus of the atoms within the crystal, exciting them into a higher energy state. When they relax and decay, gamma rays are created. These gamma photons charge the perovskite, delivering a tiny current that can be estimated.

The U.S. Defense Advanced Research Projects Agency (DARPA) is currently seeking research proposals for the development of x-ray technology capable of what the agency calls "extreme photo imaging."

As part of its Extreme Photon Imaging Capability - Hard X-Ray (EPIC-HXR) project, DARPA said it is looking to develop uncooled hard x-ray imagers based on advanced nanocrystalline materials with high spatial and energy resolution, including quantum dot and perovskite materials.

Researchers at the U.S. Department of Energy's National Renewable Energy Laboratory (NREL) have reported a breakthrough in energy-efficient phototransistors - devices that could someday help computers process visual information similarly to the human brain and be used as sensors in applications like self-driving vehicles.

The structures rely on metal-halide perovskites. Jeffrey Blackburn, a senior scientist at NREL and co-author of a new paper outlining the research, said: 'In general, these perovskite semiconductors are a really unique functional system with potential benefits for a number of different technologies'. 'NREL became interested in this material system for photovoltaics, but they have many properties that could be applied to whole different areas of science.'

A University of North Texas researcher and his team have reported a breakthrough in using additive manufacturing to further research into flexible solar panels.

Anupama Kaul, Professor of Engineering from the Departments of Materials Science and Engineering and Electrical Engineering, has successfully used additive manufacturing to print inks of 2D perovskites.

Various dangerous chemicals are currently used for agriculture and industry, including fumigants like methyl iodide, which is used to control insects and fungi. The wrong amounts or incorrect use of these fumigants can be harmful to people and degrade the ozone layer. As it’s invisible and doesn’t smell, it’s hard to tell whether there are dangerous amounts of methyl iodide present, and until now the best way to test for it was in a laboratory using expensive, complicated equipment, which isn’t practical in many real-world settings. Some cheaper, lightweight detection methods have been tried, but they didn’t have enough sensitivity and took too long to deliver results.

Now, a research team led by the ARC Centre of Excellence in Exciton Science, along with Australia’s national science agency CSIRO and the Department of Defense, has found a perovskite-based way to detect methyl iodide, with the accuracy, flexibility and speed necessary for practical use. This new sensing mechanism is also versatile enough for use in detecting a wide range of fumigants and chemical warfare agents.

A team of scientists,  led by László Forró from the School of Basic Sciences at the Ecole Polytechnique Federale de Lausanne (EPFL) in Switzerland, has developed a new X-Ray Photodetector based on perovskites and graphene.

Using 3D aerosol jet-printing technology, the team designed a new technique for creating highly efficient x-ray photodetectors that can be easily added to standard microelectronic circuits, creating more powerful medical imaging devices that can deliver better scan qualities.