Perovskite sensors

Researchers from Rice University, Northwestern University, City University of New York, University of Rennes (CNRS), University of Lille (CNRS) and University of Nebraska-Lincoln have developed a new family of FA-based two-dimensional metal halide perovskites that come very close to a “perfect” crystal at room temperature. 

These hybrid (organic–inorganic) semiconductors are engineered to achieve near-maximal crystallographic symmetry, adopting a tetragonal P4/mmm space group without in-plane or out-of-plane octahedral distortions. In contrast to most 2D perovskites, whose softer lattices tend to distort and lower symmetry, the new materials maintain a highly ordered framework inspired by three-dimensional cubic (α-phase) FAPbI₃ (FA = formamidinium).

A research team led by Ulsan National Institute of Science and Technology (UNIST) has developed a new Meniscus Pixel Printing (MPP) technique that enables the direct, mask-free patterning of perovskite photodetectors onto contact lenses - paving the way for ultralight, eye-mounted extended reality (XR) systems and hands-free robotic interfaces.

(a) Schematic of the MPP. (b) Optical images of the MPP process with a 100 µm nozzle on the substrate. The scale bar is 200 µm. (c) Conceptual illustration of dwell time-dependent dot sizes control. (d) Schematic of the Solution-mediated perovskite crystallization pathway following MPP. (e) The optical images show the crystallization during the annealing process. The scale bar is 5 mm. (f) SEM image of the resulting perovskite layer. The scale bar is 10 µm. Image from: Advanced Functional Materials 

Integrating light sensors into a contact lens remains a challenge. Traditional lithographic and inkjet methods struggle to conform to the steep curvature of a lens surface and demand costly, multi-step processing. The team’s MPP approach addresses these obstacles by harnessing a self-confined liquid meniscus formed at the tip of a micro-pipette. In this configuration, the pipette briefly touches the substrate, forming a stable ink bridge that deposits a methylammonium lead iodide (MAPbI₃) perovskite dot with precise size control governed by dwell time and retraction speed.

Researchers from the University of Barcelona, Jaume I University, Slovak University of Technology and University of Valencia have engineered ultrasensitive photodetectors based on inkjet-printed nanocrystalline films of mixed-phase “raisin bread” CsPbBr₃/Cs₄PbBr₆ perovskite integrated onto graphene. By embedding photoactive CsPbBr₃ nanocrystals within a wider-bandgap Cs₄PbBr₆ matrix, the team creates a composite architecture that enhances charge confinement while simultaneously improving environmental stability relative to conventional perovskite films.

The raisin-bread morphology plays a central role in suppressing non-radiative recombination and mitigating degradation pathways that typically limit metal-halide perovskites in photodetector operation. In this configuration, the Cs₄PbBr₆ host passivates the surface of CsPbBr₃ nanodomains and acts as a protective scaffold, helping preserve optoelectronic properties over extended operation under ambient conditions. Coupled with solution-based inkjet deposition, this strategy demonstrates that complex phase-engineered perovskite microstructures can be reproducibly formed over large areas in a maskless, vacuum-free process, supporting low-cost, scalable manufacturing.

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.