Technical / research - Page 3

Researchers from Korea's Institute for Basic Science, Korea Research Institute of Standards and Science and Chungbuk National University recently developed a new spectroscopic technique that enables real-time tracking of how perovskite nanomaterials change under light. 

The technique, called asynchronous and interferometric transient absorption spectroscopy (AI-TA), provides ultrafast measurements of excited-state dynamics and structural transformations in light-responsive materials. It overcomes major limitations of traditional ultrafast spectroscopy, which often requires long data acquisition times and can damage light-sensitive samples during measurement.

Neuromorphic computing, which mimics biological neural networks,  offers a promising approach to artificial intelligence. While software-based artificial neural networks (ANNs) have demonstrated the potential of neuromorphic architectures, a physical platform is crucial to fully realize its computational advantages. Among various physical systems, microcavity exciton polaritons have attracted attention for neuromorphic computing due to their ultrafast dynamics, strong nonlinearities, and light-based architecture, which naturally align with the requirements of brain-inspired computation. However, their practical use has been hampered by the need for cryogenic operation and intricate fabrication processes.

The operating process of polariton neuromorphic computing on image recognition task. The image information is first encoded by an SLM into an intensity-modulated laser beam. This laser beam then non-resonantly excites the exciton polaritons, leading to polariton condensation, which serves as the output information. Finally, a linear regression scheme is applied in the output layer to obtain the desired results. Image from: eLight

In a recent study, researchers from Tsinghua University and Beijing Academy of Quantum Information Sciences have demonstrated perovskite microcavity exciton polaritons operating at room temperature as a platform for reservoir computing-based artificial neural networks. This novel system displayed high-speed digit recognition with 92% accuracy using only single-step training and could open new opportunities for scalable, light-driven neural hardware.

Researchers from Sungkyunkwan University, Korea Research Institute of Chemical Technology (KRICT), Massachusetts Institute of Technology (MIT), Korea Advanced Institute of Science and Technology (KAIST), Ajou University and Ulsan National Institute of Science and Technology (UNIST) have developed an excess ligand strategy based on the chemical bath deposition (CBD) of tin oxide (SnO₂) that solves some of the common constraints of CBD like prolonged deposition times, non-uniform film formation over large-area substrates, and susceptibility to oxidation.

The conventional CBD synthesis of SnO₂ typically takes place via two competing nucleation pathways: cluster-by-cluster aggregation and ion-by-ion growth. Unfortunately, the cluster-by-cluster pathway often dominates, leading to heterogeneous deposition characterized by incomplete surface coverage and the formation of defects detrimental to charge transport and recombination dynamics. The new approach enables rapid synthesis of high-quality SnO₂ ETLs by suppressing the cluster-by-cluster pathway while facilitating the ion-by-ion pathway to create uniform films.

Researchers from the University of Science and Technology of China have developed a novel strategy for information encryption/decryption based on stimuli-responsive luminescence of 2D hybrid organic–inorganic perovskites via organic-cation engineering. 

Image credit: Angewandte Chemie 

The 2D hybrid organic–inorganic metal-halide perovskites' structure consists of inorganic layers formed from lead and iodide ions (linked PbI₆ octahedra) with organic cations arranged between them. They are easy to produce, inexpensive, and printable, while demonstrating interesting optoelectronic properties.

Researchers from China's Southeast University and Beijing Information Science and Technology University have explained that charge transport layers play a big role in facilitating the extraction and injection of carriers in perovskite solar cells (PSCs), but the performance of PSCs fabricated with conventional charge transport materials tends to exhibit significant hysteresis and instability. 

To address this issue, the team used the composite TiO₂/SnO₂ with superior electron mobility and stability and the low-cost CuSCN as bilayer electron transport layer (ETL) and hole transport layer (HTL) materials, respectively. The PSCs with the p-n-n (p-type FA_xMA_1-xPbI_xBryCl_3-x-y (FA=CH(NH₂)₂), MA=CH₃NH₃)-n-type SnO₂-n-type TiO₂) construction of FTO/TiO₂/SnO₂/FA_xMA_1-xPbI_xBryCl_3-x-y/CuSCN/C/FTO have been investigated via computation simulation and experiment. It was observed that the performance of PSCs with p-n-n structure surpassed that of n-n-p (n-type SnO₂-n-type TiO₂-p-type FA_xMA_1-xPbI_xBryCl_3-x-y) structure, benefiting from the existence of the bilayer ETL with p-n-n structure, which improves the collection ability, and the lifetime and mobility of photogenerated carriers. 

Researchers from Lukasiewicz Research Network - PORT Polish Center for Technology Development, CINTRA (CNRS-International-NTU-THALES Research Alliance), Universitas Indonesia, Nicolaus Copernicus University in Torun and Institut Lumiere Matiere UMR 5306 CNRS have scaled up a new type of light-emitting material - known as a scintillator - by  embedding it with nano-engineered metallic structures, unlocking performance  previously thought unattainable in bulk materials.

Scintillators are special substances that emit visible light when exposed to  high-energy radiation like X-rays or gamma rays. They are critical in numerous fields, from medical imaging and security screening to high-energy physics experiments. But traditional scintillators have limitations: they often emit weak signals or respond slowly, making them less efficient for demanding applications. Nanoplasmonics - a field that manipulates the behavior of light on the  nanoscale using tiny metallic structures - could address this.

Researchers from Zhejiang University, Jietai New Energy Technology, Yangzhou University, Westlake Institute for Advanced Study, Marmara University and Dongfang Electric (Hangzhou) Innovation Institute have used self-assembled monolayers (SAMs) to design a wide-bandgap (WBG) perovskite solar device, that achieved a power conversion efficiency (PCE) of 22.8%. 

Integration with crystalline silicon TOPCon subcells further enabled the construction of a perovskite/TOPCon tandem device with a PCE of 31.1% (certified 30.9%).

Printing techniques are an attractive industrial pathway towards perovskite solar cells (PSCs) manufacturing due to their compatibility with large-scale, continuous production. However, SnO₂ nanoparticles - commonly used as the electron transport layer - tend to aggregate during the printing process, leading to non-uniform film formation. This aggregation introduces crystallization defects in the perovskite layer and creates interfacial charge transport barriers, posing a challenge to further efficiency improvements.

Image credit: Joule

Researchers from China's Dalian Institute of Chemical Physics, Liaoning Normal University, Hubei University, Wuhan Textile University, Zhejiang University, Eastern Institute of Technology, University of Chinese Academy of Sciences and Australia's University of Technology Sydney have developed a layer of “molecular glue” that can effectively anchor the solute that suspends the monodisperse SnO₂ nanoparticles into a uniform thin film and adhere it to the top perovskite during the mechanical blading process. 

Researchers from Taiyuan University of Technology, University of Electronic Science and Technology of China, Southwest Jiaotong University and Shimmer Center have explained that unbalanced carrier injection and internal defects within the perovskite pose significant challenges to the performance of perovskite optoelectronic devices. To address this issue, they developed a strategy of functional molecule surface infiltration treatment.

In the new treatment, a 1,3,5-Tris(1-phenyl-1H-benzimidazol-2-yl)benzene (TPBi) acetone solution is used to treat the perovskite film. Such treatment facilitates the reconstruction of the perovskite film’s surface and promotes the infiltration of TPBi into the grain boundaries, thereby reducing defects and effectively enhancing electron injection between the emitting layer and the transport layer. 

Researchers from MIT, University of Wisconsin-Madison, Rensselaer Polytechnic Institute, University of Louisville, University of Illinois Urbana−Champaign, Yonsei University and Seoul National University have developed a technique for peeling ultra-thin crystalline electronic membranes away from their substrates to facilitate the high-throughput production of scalable, ultrathin, freestanding perovskite systems. The team used thin film membranes developed in their experiments to create a record-breaking infrared-detecting sensor that could be used in night vision eyewear or autonomous vehicles.

Study author Chang-Beom Eom, a professor of materials science and engineering at the University of Wisconsin-Madison, is an expert in crystalline perovskite oxides, containing oxygen and, typically, transition metals in a distinct atomic arrangement. These materials are particularly stable and strong when produced as thin films and can be precisely engineered at the atomic level. They also offer a wide range of tunable functions, including superconductivity, oxygen catalysis, magnetoresistance, and insulating behaviors. If incorporated into next-generation devices, these films could lead to a whole range of new gadgets, including improved fuel cells, field-effect transistors, spintronic-based memory devices and a wide range of detectors.