Perovskite sensors

Researchers from the National University of Singapore (NUS), led by Professor Liu Xiaogang from the Department of Chemistry, have developed a perovskite-based 3D imaging sensor that has an extremely high angular resolution, which is the capacity of an optical instrument to distinguish points of an object separated by a small angular distance, of 0.0018o. This innovative sensor operates on a unique angle-to-colour conversion principle, allowing it to detect 3D light fields across the X-ray to visible light spectrum.  

 Design of the 3D light-field sensor on the basis of pixelated color conversion. Image from study 

A light field encompasses the combined intensity and direction of light rays, which the human eyes can process to precisely detect the spatial relationship between objects. Traditional light sensing technologies, however, are less effective. Most cameras, for instance, can only produce two-dimensional images, which is adequate for regular photography but insufficient for more advanced applications, including virtual reality, self-driving cars, and biological imaging. These applications require precise 3D scene construction of a particular space.

Researchers from Pennsylvania State University have developed a narrowband (NB) imaging sensor combining R/G/B perovskite NB sensor array (mimicking the R/G/B photoreceptors in the eye) with a neuromorphic algorithm (mimicking the intermediate neural network of the human visual system) for high-fidelity panchromatic imaging.

A photo of a perovskite NB PD array made in this work. Image from study

Compared to commercial sensors, the team used perovskite “intrinsic” NB photodetectors to exempt the complex optical filter array. In addition, They used an asymmetric device configuration to collect photocurrent without external bias, enabling a power-free photodetection feature. These results presented a promising design for efficient and intelligent panchromatic imaging.

University of North Carolina at Chapel Hill researchers have demonstrated that self-powered polycrystalline perovskite photodetectors can rival the commercial silicon photomultipliers (SiPMs) for photon counting. 

The new type of photon counting detector could have applications in consumer electronics, sensors, optical communication, radiation detection, and more. It could also offer safer medical imaging and enhance nighttime photography. The team's recent work could open up various new applications of photon counting for perovskites that use their unique defect properties. Compared to current technologies on the market, the team’s technology is reportedly more cost effective and does not require external power sources, broadening the scope of how the technology can be applied

Researchers from Eindhoven University of Technology and TNO at Holst Centre have developed a sensor that converts light into an electrical signal at an astonishing 200% efficiency – a seemingly impossible figure that was achieved through the exceptional nature of quantum physics.

SA schematic of the photodiode architecture

The team of scientists sees its invention potentially used in technology that monitors a person's vital signs (including heartbeat or respiration rate) from afar, without the need for anything to be inserted or even attached to the body.

Researchers from Japan's Teikyo University of Science and Toin University of Yokohama, under the JST Strategic Basic Research Program PRESTO, have developed a new near-infrared light sensor by using perovskite materials that convert weak near-infrared light to visible light.

Near-infrared light is used in a wide range of applications, such as in infrared cameras (night vision cameras), infrared communication (wireless communication), optical fiber communication, remote control, and biometric authentication. The detection of weak light in the near-infrared region and improvement of sensitivity are indispensable for the advancement in optical communication technology, medical diagnosis, environmental monitoring, and other fields. Compound semiconductors (e.g., InGaAs) having an optimal absorption band of 900–1700 nm, are used to detect light in the near-infrared region. However, these systems are expensive because of their complicated manufacturing process that involves the use of rare metals and is limited by noise interference. Moreover, such semiconductors do not exhibit visible light detection accuracy comparable to that achieved using silicon (Si) and other compounds.

A team of researchers from China's Chinese Academy of Sciences (CAS), Jilin University and Beijing Institute of Technology, has used perovskite and quantum dots to build an ultraviolet radiation measurement device. 

Measuring the intensity of ultraviolet light in outdoor conditions is important because more intense UV light can lead to faster sunburns and potentially to skin cancer in later years. In this new study, the researchers built a wearable device that can measure ultraviolet radiation in real-time and send the information to a smartphone.

Researchers from China's Jilin University have designed a spray coated spherical perovskite photonic sensor made of phenyl ethyl ammonium/formamidinium lead halide (PEA₂FAn_-1Pb_nX_3n+1). The researchers utilized the perovskite formulations to regulate the crystallization rate. Cyclic spray-coating and the solution concentration were used to control the coating thickness from a few nanometers to hundreds of micrometers. 

Sphere imagers featuring specific wavelength recognition and wide-angle imaging are required in order to meet the fast development pace of modern technology. However, it remains challenging to deposit high-quality photosensitive layers on sphere substrates from low-cost solution processes. In this recent study, the team demonstrated the feasibility of using a rapid spray-coating procedure to fabricate perovskite hemispherical photodetectors that can execute lens-free scanning at nearly 180°, considerably decreasing the reliance on complex optical components.

Researchers at the University of Toronto and the Barcelona Institute of Science and Technology recently reported new solution-processed perovskite photodetectors that exhibit remarkable efficiencies and response times. The photodetectors have a unique design that prevents the formation of defects between its different layers.

The researchers explained that there are applications for which fast photodetection is required in wavelength ranges beyond human vision. "Silicon, the legacy approach—and ideal for electronic readout—does not on its own unite high efficiency with high-speed, as a result of its indirect bandgap, a property of silicon's band structure that produces weak absorption (hence a need for thick silicon) in the near infrared", said University of Toronto's Amin Morteza Najarian. 

Researchers from China's University of Science and Technology of China (USTC) and Shaanxi Normal University have synthesized a new molecular perovskite, DABCO-CsBr₃ (DABCO = N,N′-diazabicyclo[2.2.2]octonium), for use in flexible X-ray detectors. The material was prepared from DABCO, CsBr, and HBr in aqueous solution and obtained in the form of colorless crystals.

The team found that DABCO-CsBr₃ possesses good mechanical properties for use in flexible devices. Compared with the metal-free equivalent DABCO-NH4Br₃, DABCO-CsBr₃ has a stronger X-ray attenuation capability. The researchers built a flexible X-ray detector, using a poly(vinylidene fluoride) (PVDF) polymer matrix that was mixed with DABCO-CsBr₃ to create a composite film. This film shows a linear relationship between the X-ray-induced current density and the X-ray dose rate. According to the team, the material could have applications in X-ray security screening systems or medical diagnostics.

UK-based Quantum Solutions started to ship evaluation samples of its next-gen perovskite quantum dots (pQD) X-Ray Scintillators. The company says that these scintillators offer very high sensitivity, high light output, high resolution, low afterglow and can be processed on large areas.

Quantum Solutions started developing these materials in 2020, and already managed to increase the light output (brightness) 10 times over. The company says that this is due to the unique perovskite structure that allows to tune the properties by composition, particle sizes/shapes, ligands, etc. The product already matches the performance of commercial CsI(Tl) and GADOX scintillators. The company is working with key customers in the medical field and non-destructive testing field, and are continuing to develop and customize the product.