April 2022

Developing efficient and stable luminescence materials is critical for avoiding unnecessary waste of electric energy. Single emitters with broadband emission, like lead halide perovskites, are attracting attention for artificial illumination and display applications. To develop lead-free and stable perovskites with broadband emission, researchers from China's Dalian Institute of Chemical Physics, University of Chinese Academy of Sciences (CAS) and Shandong University have examined low-dimensional bismuth halide perovskites.

'The single emitters with broadband emission can circumvent critical problems faced in the traditional mixed and multicomponent emitters such as the efficiency losses caused by self-absorption, the complex device structure, and the colors instability due to the different degradation rates of phosphors,' said paper author Rengui Li, a professor with the State Key Laboratory of Catalysis, Dalian National Laboratory for Clean Energy, Dalian Institute of Chemical Physics, Chinese Academy of Sciences (CAS). 'Lead halide perovskites have emerged as highly attractive next-generation optoelectronic materials for light-emitting applications due to their extraordinary photoelectric properties.'

EPFL scientists in Neuchâtel have reported a tandem solar cell that can deliver a certified efficiency of 29.2%. This achievement was made possible by combining a perovskite solar cell with a textured silicon solar cell.

One obstacle the team encountered was finding a way to evenly coat the silicon surface'which is intentionally rough, or textured'with a thin film of halide perovskites. A textured surface is used in order to minimize light reflection. This kind of system can already be found in all commercially available crystalline silicon cells.

Researchers from the Singapore-HUJ Alliance for Research and Enterprise (SHARE) and Nanyang Technological University have developed semi-transparent perovskite solar cells with over 13% efficiency and 27% transparency using plasmonic Au nanorods.

Semitransparent hybrid perovskites can open the door to applications in smart windows and building-integrated photovoltaics (BIPV). One route towards semitransparency is thinning the perovskite film, which has several benefits like cost efficiency and reduction of lead. However, this tends to result in reduced light absorbance. To compromise this loss, it is possible to incorporate plasmonic metal nanostructures, which can trap incident light and locally amplify the electromagnetic field around the resonance peaks.

Researchers from EPFL, Tianjin University, Nanjing Tech University, The University of Tokyo, Shanghai University and Toyota Motor Corporation have used ionic liquids (ILs) with halide anions as additives to improve the performance and stability of a perovskite solar cell.

Image from study in Cell Reports Physical Science

Ionic liquids are viewed as a "greener" alternative to organic solvents due to their lower volatility and flammability, as well as to their wide liquid-state window.

Researchers from South Korea's Institute for Basic Science (IBS), Gwangju Institute of Science and Technology and Korea University have developed perovskite micro cells with a power conversion efficiency of 20.1% that can be used in colored solar windows.

the colored solar window with the metal'insulator'metal (MIM) resonant structure. The inset shows a cross-sectional view of the perovskite microcell in the colored solar window. Image from Nature Communications

The devices were built using a lift-off-based patterning approach based on swelling-induced crack propagation.

A collaborative research effort involving scientists from the US National Renewable Energy Laboratory (NREL) and other collaborators, has examined how well perovskite technology might work in the space, such as for powering satellites. The research group has presented guidelines to test the radiation-tolerating properties of perovskites intended for use in space.

'Radiation is not really a concern on Earth, but becomes increasingly intense as we move to higher and higher altitudes,' commented Ahmad Kirmani, a postdoctoral researcher at NREL and lead author of the new study.

A group of scientists from the University of Wuppertal, the University of Tübingen, the University of Potsdam, HZB, Max Planck Institute and the University of Cologne in Germany recently developed a perovskite-organic tandem solar cell with optimized charge extraction, a high open-circuit voltage and a thickness of just 1 µm.

The tandem configuration includes a narrow-bandgap organic subcell with a p-i-n-type architecture based on the polymer PM6 and molybdenum oxide (MoOx) as the hole extraction layer (HEL). The cell has a power conversion efficiency of 17.5%, an open-circuit voltage of 0.87 V, a short-circuit current of 26.7 mA cm'², and a fill factor of 75%. The wide-bandgap perovskite subcell was built with a perovskite known as FA_0.8Cs_0.2Pb(I_0.5Br_0.5)₃, with an efficiency of 16.8%, an open-circuit voltage of 1.34 V, a short-circuit current of 15.6 mA cm'², and a fill factor of 81%.

KAUST researchers have shared a detailed view of how electrical charges behave inside perovskites, which could guide efforts to improve the performance of next-generation solar cells based on these materials.

When light hits a perovskite, it excites negatively charged electrons and leaves behind positively-charged 'holes' within the material's crystalline structure. These electrons and holes can then move through the perovskite to generate an electrical current. But the charge carriers could also recombine instead, which wastes the energy they carry.

The Centre for Solar Energy and Hydrogen Research Baden-Württemberg (ZSW), aiming to fast-track tandem solar technology's time to market, has put two new high-performance coating plants into operation.

The systems produce tandem solar cells consisting of a perovskite solar cell that can be combined with other types of solar cells. The various layers are deposited under ultra-clean conditions. Companies in the solar sector can take advantage of these capabilities to optimize their developments in the area of tandem solar cells.

A team of scientists, led by Mohammad Nazeeruddin at École polytechnique fédérale de Lausanne (EPFL), has found a way to address the scaling up challenges of perovskites. The scientists have developed an easy solvothermal method to produce single-crystalline titanium dioxide rhombohedral nanoparticles that can be used to build a perovskite film.

The new structure is said to feature a lower amount of lattice mismatches, referring to the "ladder-like" structure of the titanium dioxide nanoparticles. This translates into a lower number of defects, which ensures better electron flow throughout with lower power loss.