#halides

Reducing halide segregation in wide-bandgap mixed-halide perovskite solar cells using redox mediators

Multi-junction solar cells, solar cells comprised of many individual semiconductor junctions stacked together, have the potential of outperforming single-junction solar cells both in terms of efficiency and stability. In recent years, material scientists and engineers have been trying to identify viable material combinations for fabricating these solar cells. A class of materials found to be promising for these applications is metal halide perovskites, semiconductors with inherent properties that are advantageous for developing various optoelectronic devices and photovoltaics. While the efficiency of tandem solar cells based on these semiconductors has gradually improved and recently reached 24%, their stability is hindered by the severe phase segregation of mixed-halide perovskites. Researchers at City University of Hong Kong recently set out to address this limitation of mixed-halide perovskite solar cells. Their paper, published in Nature Energy, introduces a strategy that could improve the long-term stability and photovoltage of these solar cells, utilizing newly designed redox mediators based on anthraquinone compounds.

Ultra-long room temperature phosphorescence of indium-based organic inorganic metal halide

A study published in the journal Science China Chemistry found that PBA3[InCl6]·H2O exhibits a special "herringbone" stacking mode that enables abundant weak interactions between organic ligands and metal halide units. While the light source with 420 nm wavelength is used for excitation, the crystals preferentially display the ultra-long triplet phosphorescent emission with 290.4 ms lifetime decay. "DFT calculation shows that PBA3[InCl6]·H2O is a direct band gap semiconductor. Due to the abundant weak interactions between metal octahedral and organics in the crystal, there is an energy or electron transfer between the inorganic anions and organic cations during the photo-excitation process. The [InCl6]3- octahedron helps to stabilize the triplet excitons prompting the production of extra-long phosphorescence with more than 7 s to the naked eye," Tian says.

Scintillating science: Researchers improve materials for radiation detection and imaging technology

A team of Florida State University researchers has further developed a new generation of organic-inorganic hybrid materials that can improve image quality in X-ray machines, CT scans and other radiation detection and imaging technologies.

Professor Biwu Ma from the Department of Chemistry and Biochemistry and his colleagues have developed a new class of materials that can act as highly efficient scintillators, which emit light after being exposed to other forms of high energy radiations, such as X-rays.

The team's most recent study, published in Advanced Materials, is an improvement upon their previous research to develop better scintillators. The new design concept produces materials that can emit light within nanoseconds, orders of magnitude faster than previously developed materials, allowing for better imaging.

"Reducing the radioluminescence decay lifetime of scintillators to nanoseconds is an important breakthrough," Ma said. "Using a hybrid material made up of both organic and inorganic components means each component can be used for the part of the process where it is most effective."

Highly emissive Sb3+-doped 0D cesium indium chloride nanocrystals with switchable photoluminescence

All-inorganic lead-free luminescent metal halide nanocrystals (NCs) are very important in optoelectronics, but their applications are limited by the low photoluminescence (PL) efficiency. It is an effective approach via ns2-metal ions doping for tailoring the optical properties of metal halide NCs and expanding their applications.

However, the PL origin of ns2-metal ion doped metal halides remains controversial and not well understood. Moreover, the controlled synthesis of Sb3+-doped 0D In-based halide NCs and the size effect on the optical properties and excited-state dynamics remain unexplored.  

In a study published in Nano Today, the research group led by Prof. CHEN Xueyuan from Fujian Institute of Research on the Structure of Matter (FJIRSM) of the Chinese Academy of Sciences (CAS) reported the controlled synthesis of Sb3+-doped 0D Cs3InCl6 NCs with tunable sizes and investigated the effect of NC size on the optical properties and excited-state dynamics of Sb3+.