Perovskite sensors - Page 2

Researchers from Dongguan University of Technology have demonstrated a perovskite/graphene heterostructure that overcomes key challenges in metal-halide perovskite X-ray detectors, such as charge recombination caused by thick, defect-prone films. 

By combining CsPbBr₃ perovskite’s strong X-ray absorption and photophysical performance with graphene’s ultrahigh carrier mobility (> 10⁴ cm²·V⁻¹·s⁻¹), the heterostructure achieves efficient charge transport and reduced non-radiative losses. A MAPbCl₃ buffer layer at the perovskite/Si interface further alleviates lattice mismatch and enhances adhesion by 10×. 

Metal halide perovskites offer exceptional sensitivity for direct x-ray detection through direct current (DC) signals, but their soft lattices and mobile ions lead to signal instability and nonlinear current responses under direct current (DC) bias.

A team led by LI Yunlong from the Shenzhen Institutes of Advanced Technology (SIAT) of the Chinese Academy of Sciences, together with ZHU Ziyao and XU Xiumin from Anhui University, recently proposed an alternating current (AC) bias capacitance readout approach for metal halide perovskite X-ray detectors. This method replaces the conventional DC bias with a low-amplitude AC bias and reads out the accompanying capacitance modulation, effectively reducing the influence of ion migration on signal output.

A Fudan University team has developed a high-performance 2D Ruddlesden–Popper (RP) phase perovskite photodetector by employing an asymmetric electrode configuration that dramatically enhances optoelectronic performance.

In their work, single-crystal (PEA)₂PbBr₄ (PPB) microplates, grown via a liquid–air interfacial method with thicknesses from ~60 to 350 nm, served as the active layer. By introducing two dissimilar metal electrodes, the researchers formed asymmetric contact barriers, enabling more effective band alignment and charge extraction compared with conventional symmetric devices.

Scientists led by Northwestern University and Soochow University in China have developed a perovskite-based detector, which they deem as the first one capable of capturing individual gamma rays for SPECT imaging with unprecedented precision. Under the guidance of Mercouri Kanatzidis (Northwestern) and Yihui He (Soochow), this achievement paves the way for sharper, faster, and more affordable nuclear medicine imaging, promising shorter scan times, clearer results, and lower radiation doses for patients

“Perovskites are a family of crystals best known for transforming the field of solar energy,” said Northwestern’s Mercouri Kanatzidis. “Now, they are poised to do the same for nuclear medicine. This is the first clear proof that perovskite detectors can produce the kind of sharp, reliable images that doctors need to provide the best care for their patients.”

Researchers from the Chinese Academy of Sciences, Hong Kong University of Science and Technology, Beihang University and the Hong Kong Polytechnic University have reported the development of a focus-tunable curved imaging system based on an ultrathin perovskite curved image sensor. The device was designed to address the limitations of conventional curved sensors, which cannot adjust their curvature to match the Petzval surface across different focal ranges.

The human visual system and the focus-tunable real-time curved imaging system. (A) Schematic of the human visual system. (B) Schematic of the focus-tunable real-time curved imaging system. Image from: Science Advances

The perovskite image sensor was fabricated with a total thickness of 5.4 μm with a hierarchical mesh design. This architecture allows the device to conform to hemispherical surfaces with varying radii while maintaining mechanical stability during deformation, as the mesh interconnects accommodate local strain. The sensor achieves a low detection limit of 10 nW cm⁻², which is below the sensitivity range of human photoreceptor cells, and maintains a stable dynamic photoresponse. 

Conventional pathogen detection methods tend to suffer from limitations such as prolonged processing time, operational complexity, or insufficient sensitivity. To address the need for rapid and highly sensitive detection technologies, researchers from China's Hefei University of Technology have developed a machine learning-assisted fluorescent sensor array strategy, constructing a 3 × 6 sensing platform utilizing three water-soluble perovskite quantum dots (PQDs) with distinct fluorescent properties. 

The array generates significant fluorescence color changes through electrostatic interactions between PQDs and bacterial surfaces, as well as Aggregation-Caused Quenching (ACQ) effects. Relative fluorescence color changes (ΔRGB) were captured using a smartphone and subsequently analyzed through machine learning algorithms, including K-Nearest Neighbors (KNN) and principal component analysis (PCA). 

Researchers from China's Jilin University have demonstrated significant progress in non-contact heart rate detection by leveraging the properties of perovskite (MAPbI₃) nanowire photodetectors. While nanowire photodetectors typically benefit from surface state effects, their performance is often constrained by the intrinsic material characteristics that define surface state distribution and charge-trapping capability.

This study presents an approach to overcome these limitations through targeted surface state engineering using C60 molecules. By integrating C60 with MAPbI₃ nanowires, electron depletion zones are established, which in turn reduce noise current by 74% and enhance photoresponse by a factor of three. The resulting device achieves a specific detectivity of 6.7×10¹⁴ Jones, marking the highest reported performance for MAPbI₃ nanowire-based photodetectors to date.

Researchers from China's Yuncheng University, Beihang University, CRCC Technology Research Institute and the Fourth Medical Center of PLA General Hospital have developed a novel electrochemical biosensor NF/KbE-CS/AuNPs/PVK/GCE for organophosphorus pesticide detection, using white kidney beans and chitosan (KbE-CS) as the detection enzyme source. 

The gold nanoparticles (AuNPs) and perovskite (PVK) composite were prepared for the synergistic electrocatalytic amplification. By introducing PVK, the electron transfer capability of the modified electrode was improved owing to the increased specific surface area and the enhanced conductivity. 

Artificial photosynthesis technology that directly converts solar energy into hydrogen, or an 'artificial leaf', has recently attracted significant attention due to its minimal space requirement and low cost compared to wired photoelectrochemical and photovoltaic-electrochemical systems for solar hydrogen production. However, it remains a challenge to achieve a practical-size solar water-splitting device that can fulfill the criteria of a solar-to-hydrogen conversion efficiency above 10%, long-term durability, and scalability. 

A high-efficiency wireless artificial leaf-based solar hydrogen production system. Image credit: UNIST
 

In a recent study, researchers at Ulsan National Institute of Science and Technology (UNIST) developed 1 cm² perovskite-based photoelectrodes using a defect-less, chlorine-doped formamidinium lead triiodide as photo-absorber and ultraviolet-insensitive tin oxide as an electron transport layers. 

Researchers at ETH Zurich and Empa have developed a new perovskite-based image sensor that enables better color reproduction and fewer image artefacts with less light. According to the team, perovskite sensors are also particularly well suited for machine vision.

Perovskite image sensors can theoretically capture three times as much light on the same surface area as conventional silicon image sensors – with three times the resolution. (Illustration: Sergii Yakunin / ETH Zurich / Empa)

Image sensors are ubiquitous and can be found in every smartphone, digital camera and many other electronic devices. They distinguish colors in a similar way to the human eye, where individual cone cells recognize red, green and blue (RGB). In image sensors, individual pixels absorb the corresponding wavelengths and convert them into electrical signals. The vast majority of image sensors are made of silicon. This semiconductor material normally absorbs light over the entire visible spectrum. In order to manufacture it into RGB image sensors, the incoming light must be filtered. Pixels for red contain filters that block (and waste) green and blue, and so on. Each pixel in a silicon image sensor thus only receives around a third of the available light.