Technical / research - Page 22

Researchers at Imec have reported a metal halide perovskite LED (PeLED) stack that emits 1,000x more light “than state-of-the-art OLEDs”. The team developed a transparent PeLED architecture, that combines low optical losses with excellent current-injection properties. 

In this work, the team showed that perovskite semiconductor optical amplifiers and injection lasers are within reach using this type of transparent PeLED.

Researchers from China's Qingdao University of Science and Technology, Beijing Huairou Laboratory and the Chinese Academy of Sciences have developed an additive with a conjugated structure, 2,2′-diamino-[1,1′-biphenyl]-4,4′-dicarboxylic acid (DBDA), containing amino and carboxyl groups. The additive was introduced to convert tensile strain to compressive strain in perovskite films. 

Lattice tensile strain generated during the preparation of perovskite thin films has detrimental effects on the efficiency and stability of perovskite solar cells (PSCs). The scientists in this work examined this additive as a way to mitigate these harmful effects.

Researchers at the Korea Institute of Science and Technology (KIST), Korea University, Korea Institute of Science and Technology, Yonsei University and Hyundai Motor Company have reported an infiltration technique that enables in situ synthesis of extremely small, thermally stable perovskite (Sm_0.5Sr_0.5)CoO₃ nanocatalysts on the inner surface of porous SOC electrodes. 

The team identified certain impurity phases, such as SrCO₃, that cause fatal degradation and eliminated them using a rational complexation strategy optimized for individual constituent cations. Consequently, they fabricated ∼ 20 nm diameter, highly pure, single-phase nanocatalysts that achieved more than double the performance of a cell with standard (La,Sr)(Co,Fe)O₃– and (La,Sr)CoO₃-based air electrode. 

Researchers at Germany's Forschungszentrum Jülich have reported a method to fabricate >1-micrometer thick perovskite films by employing hole-transporting bilayers of self-assembled monolayers (SAMs) and poly[bis(4-phenyl) (2,4,6-trimethylphenyl)amine] (PTAA). Recognizing the critical role transport layers play in exacerbating thickness-dependent losses, the team optimized a dual-layer hole transport architecture to reduce resistive losses and recombination. The authors achieved remarkable efficiency retention at over 1 micron thickness.

This work focuses on a solar cell architecture that decouples thickness from efficiency limitations. By sandwiching specialty organic films around the perovskite layer, the authors enabled micron-scale thicknesses without forfeiting peak performance. Their design notably achieves a remarkable 20.2% efficiency at over 1 micron thickness with minimal losses compared to thinner versions.

A team led by RIKEN researchers recently investigated how certain perovskite materials convert light into electricity. Their findings could hel improve their efficiency and use in solar cells.

Solar cells convert light into electricity by a phenomenon known as the photovoltaic effect. The vast majority of solar cells consist of two semiconductors put together—one with an excess of electrons and the other being electron deficient. This is because the setup has a high conversion efficiency. But another photovoltaic effect has also been attracting attention—the bulk photovoltaic effect, so called because it only involves a single material. While its conversion efficiency is currently rather low, recent research has suggested ways for improving its efficiency.

Researchers from Spain's Public University of Navarra and Rey Juan Carlos University have used perovskites to create lossy mode resonance (LMR) devices, which are devices that act like super-sensitive detectors that can pick up even the slightest changes in their environment.

The key to making LMR devices work is choosing the right material for a thin film. Perovskites have unique properties that allow it to generate LMRs, which are like 'sweet spots' where the material interacts with light in a special way. These sweet spots can be fine-tuned by adjusting the thickness of the perovskite film, among other parameters.

Scientists at South China University of Technology and Guangzhou Aifo Communication Technology have develop fast-response humidity sensors based on all-inorganic lead-free Cs₂PdBr₆ perovskite integrated with bulk acoustic wave resonators for motion monitoring.

The proposed sensor reportedly exhibits faster response and recovery speed than most other perovskite-based humidity sensors, indicating its potential utilization in real-time monitoring of body movements. In addition, the perovskite-based sensor shows remarkable logarithmic linearity response as well as superior repeatability and stability in the relative humidity range of 11%-85%. 

A team of researchers from Brookhaven National Lab, Georgia Institute of Technology, Argonne National Laboratory, Istituto CNR di Scienze e Tecnologie Chimiche “Giulio Natta” (CNR-SCITEC) and Helmholtz-Zentrum Berlin für Materialien und Energie has examined the mechanism that causes degradation of formamidinium-based halide perovskites and have been able to stop it using a thin layer of molecules that repels water.

“Perovskites have the potential of not only transforming how we produce solar energy, but also how we make semiconductors for other types of applications like LEDs or phototransistors. We can think about them for applications in quantum information technology, such as light emission for quantum communication,” said Juan-Pablo Correa-Baena, assistant professor in the School of Materials Science and Engineering and the study’s senior author. “These materials have impressive properties that are very promising.”

Researchers from Huazhong University of Science and Technology, Tohoku University, Lanzhou University, Tsinghua University and Georgia Institute of Technology have reported on a new method to enhance the electrochemical surface area (ECSA) in a calcium-doped perovskite, La_0.6Ca_0.4MnO₃ (LCMO64), which could help in overcoming a common bottleneck in the application of perovskite oxides as electrocatalysts in hydrogen fuel cells.

Perovskite oxides have potential for use in various fields thanks to their interesting and diverse properties. Their high intrinsic activities also position them as a promising alternative to noble metal catalysts for efficiently catalyzing the oxygen reduction reaction (ORR). However, their application is still hampered by their poor electrical conductivity and low specific surface area.

Researchers at the Tokyo Institute of Technology (Tokyo Tech), in collaboration with Tohoku University, Australian Nuclear Science and Technology Organization (ANSTO) and the High Energy Accelerator Research Organization (KEK), recently investigated a promising material for next-generation electrochemical devices: hexagonal perovskite-related oxide Ba₇Nb_3.8Mo_1.2O_20.1. The team unveiled the material's unique ion-transport mechanisms, that could pave the way for better dual-ion conductors.

Clean energy technologies are the cornerstone of sustainable societies, and solid-oxide fuel cells (SOFCs) and proton ceramic fuel cells (PCFCs) are among the most promising types of electrochemical devices for green power generation. These devices, however, still face challenges that hinder their development and adoption.