Technical / research - Page 2

Researchers from the University of Limoges (France), SODERN, KELENN Technology, and the University of Monastir (Tunisia) have set out to tackle the challenges hindering the large-scale industrial production of perovskite solar cells (PSCs). The developed a novel digital deposition technique, Digital Materials Deposition (DMD), to prepare compact SnO₂ films, serving as electron transport layers (ETL) in PSCs. 

DMD printing offers a rapid, scalable solution that forms high-quality films without material waste, a key factor for commercializing PSCs. By optimizing ink formulation and printing parameters, homogeneous, high-quality SnO₂ layers were successfully printed and used as selective contacts in triple-cation perovskite solar cells fabricated in ambient conditions. 

Textile Ceramic Technology (TCT) is an innovative industrialized dry-construction system that incorporates a stainless-steel wire mesh as a structural framework for embedding ceramic tiles. Recently, researchers from Spain's International University of Catalonia (UIC), Leitat and France's Grenoble Alpes University set out to integrate photovoltaic (PV) solar cells into the TCT framework, creating a system capable of efficiently constructing industrialized photovoltaic envelopes that can cover large surfaces in a timely manner. 

The team opted for perovskite-based PVs due to several key advantages, including low cost, lightweight design, and customizable coloration. These properties not only enhance energy generation but also provide aesthetic possibilities. The versatility of the TCT system allows for a wide range of architectural designs based on a fundamental modular element—the brick—facilitating diverse configurations. This synergy between perovskite technology and the adaptable nature of TCT opens new opportunities for creating visually appealing and energy-efficient building envelopes. 

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.

Perovskite solar cells (PSCs) can achieve high power conversion efficiencies but usually rely on vacuum-deposited metallic contacts, leading to high material costs for noble metals and stability issues for more reactive metals. Carbon-based materials offer a cost-effective and potentially more stable alternative. The vast majority of carbon-electrode PSCs use the negative-intrinsic-positive (n-i-p) or “hole-transport-layer-free” architectures.

Recently, researchers at the University of Oxford, Imperial College London, Philipps-University Marburg, Swansea University and Fraunhofer ISE conducted a systematic study to assess the compatibility of “inverted”, p-i-n configuration PSC contact layers with carbon top electrodes. 

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. 

A research team, led by Professor Yang Chang-deok at Ulsan National Institute of Science and Technology (UNIST), recently synthesized high-quality perovskite thin films by adding a substance derived from camphor trees. It is expected to improve the lifespan and efficiency of perovskite solar cells due to the absence of residual materials, and to reduce manufacturing costs by simplifying the process.

In perovskite thin films used in solar cells, scientists tend to look for large crystal size and uniform arrangement, to allow a smooth flow of electrons and sturdy structure. Additives are used to create such high-quality films, but if residuals remain following manufacturing, they can cause performance degradation. To solve this issue, the research team used camphorquinone as a thin-film additive. Camphorquinone is a substance where an oxidation functional group is added to the camphor extracted from the camphor tree. It possesses sublimation properties like camphor, transitioning directly from solid to gas, but sublimates gradually unlike camphor. During the primary heat treatment process, it helps ensure uniform crystallization seeds, some of which sublimate, while the rest remain in the thin film long enough to grow crystals before completely sublimating during the secondary heat treatment.

Researchers at China's Westlake University and Zhejiang University have developed a passivation strategy that could neutralize surface defects in a wide range of perovskites and is also easier to integrate with existing solar cell manufacturing processes than other passivation methods introduced in the past. This strategy relies on the use of a modified alcohol solvent called fluorinated isopropanol, which limits undesirable chemical reactions between a passivation agent and perovskite layers.

"Surface defect passivation is crucial for improving the efficiency and stability of perovskite solar cells," Sisi Wang, Weizhong Tian and their colleagues wrote in their paper. "However, its reproducibility and universal applicability have not been fully explored, limiting large-scale production. We introduce a passivation strategy based on fluorinated isopropanol for full passivation of surface defects with only a thin layer of low-dimensional perovskite, which does not interfere with charge transport."

An international collaboration that includes researchers from UNSW, University of Cambridge, Colorado State University, Imperial College London, ANSTO Sydney and synchrotron facilities in Australia, the UK, and Germany recently found that dynamic nanodomains within lead halide perovskites could be vital for boosting their efficiency and stability. 

The team examined the nature of these microscopic structures, and how they impact the way electrons are energized by light and transported through the material, offering insights into more efficient solar cells.

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.

Researchers at Imperial College London have examined the influence of light and oxygen on the stability of CH₃NH₃PbI₃ perovskite-based photoactive layers. They discovered why the cells degrade so quickly, and suggested a mechanism for slowing the decline. 

Until now, researchers believed that water played a dominant role in breaking down the cells, but Dr. Saif Haque and colleagues from the Department of Chemistry at Imperial College London have discovered that cells degrade even in dry air by the action of oxygen and light.