June 2020

Australian National University (ANU) researchers have managed to push forward the efficiency of solar-to-hydrogen production that bypasses electrolysers and avoids AC/DC power conversion and transmission losses. They have recently managed to reach 17.6% efficiency, achieved with perovskite-silicon tandem absorbers, and they say their process is open to further refinement that could see clean hydrogen production become cost competitive with other fuels, including brown hydrogen and gas, more quickly than expected.

Perovskite-Si dual-absorber tandem PEC cell for self-driven water splitting. a) Schematic showing a perovskite solar cell wired to a Si photo-cathode in tandem, and a DSA anode. b) A representative general energy band diagram. Image: ANU

Australian National University (ANU) researchers, in a newly-released study lead by Dr. Siva Krishna Karuturi and Dr. Heping Shen, state that although PV modules have become a commercially viable method large-scale renewable energy generation, 'Achieving global renewable energy transition further relies on addressing the intermittency of solar electricity through the development of transportable energy storage means.'

The New Energy Center at National Taiwan University and Taiwanese PV production equipment provider E-Sun Precision Industrial have developed new production equipment to manufacture large-area p-i-n type perovskite solar cells.

Researchers from both entities said the machine can facilitate the production of low-cost perovskite cells through the MK-20 once-through process. The manufacturing process, which is based on slot-die coater and fast thermal processor (FTP) tech, is fully automatic and can currently handle small-quantity sample production.

A team of researchers led by Nanchang University in China tested a polymer-based hole transport layer for flexible perovskite solar cells, using a glue to attach it to the active perovskite. The team was able to assemble the cells into a small flexible module suitable for wearable solar applications, and says its design was inspired by the structure and movements of human vertebrae.

Bio-inspired vertebral design for scalable and flexible perovskite solar cells. Image from Nature Communications

The team reported that the solar cell measured 1.01cm² and achieved a stabilized efficiency of 19.87%. The cell was tested for 3000 hours under one-sun illumination at room temperature and was shown to retain 85% of its initial efficiency.

A team of scientists led by researchers at ITMO in Russia has proposed a quick and affordable method to create miniature optical chips in a Petri dish.

Miniature visible light devices use GaP waveguides embedded in perovskite light sources

Today's optical chips operate in the infrared (IR) range. "To make the devices even more compact, we need to work in the visible range," says Sergey Makarov, chief researcher at ITMO's Department of Physics and Engineering, "as the size of a chip depends on the wavelength of its emission."

A joint team of HZB and Humboldt-Universität (HU) Berlin researchers has succeeded in producing functional light-emitting diodes printed from a solution of semiconductor compounds. The research group used a metal halide perovskite for this purpose. This is a material that promises particularly high efficiency in generating light'but on the other hand is difficult to process.

"Until now, it has not been possible to produce these kinds of semiconductor layers with sufficient quality from a liquid solution," says Prof. Emil List-Kratochvil, head of a Joint Research Group at HZB and Humboldt-Universität. For example, LEDs could be printed just from organic semiconductors, but these provide only modest luminosity. "The challenge was how to cause the salt-like precursor that we printed onto the substrate to crystallize quickly and evenly by using some sort of an attractant or catalyst," explains the scientist. The team chose a seed crystal for this purpose: a salt crystal that attaches itself to the substrate and triggers formation of a gridwork for the subsequent perovskite layers.

Helio Display Materials, based in the UK, was spun-off from both Oxford and Cambridge University, to commercialize photoluminescent and electroluminescent perovskite-based materials for the display industry.

Following is an interview with Helio's CEO, Simon B. Jones, discussing the company's technology and business.

An international team of researchers has announced the development of the world's most compact perovskite-based semiconductor laser that works in the visible range at room temperature. According to the authors of the research, the laser is a nanoparticle of only 310 nanometers in size (which is 3,000 times less than a millimeter) that can produce green coherent light at room temperature.

The scientists succeeded in exploiting the green part of the visible band, which was considered problematic for nanolasers. "In the modern field of light-emitting semiconductors, there is the 'green gap' problem," says Sergey Makarov, principal investigator of the article and professor at the Faculty of Physics and Engineering of ITMO University. "The green gap means that the quantum efficiency of conventional semiconductor materials used for light-emitting diodes falls dramatically in the green part of the spectrum. This problem complicates the development of room temperature nanolasers made of conventional semiconductor materials."

Researchers in Japan's Kyushu University have modified the tin(IV) oxide layer of a perovskite device with a fullerene-derivative-based self-assembled monolayer to produce a cell they claim offers stability and a reduction in the hysteresis effect which makes predicting power output so tricky.

The Kyushu University team has developed a surface treatment method for perovskite cell production they say reduces hysteresis ' an effect which afflicts perovskite devices because their output depends on a variety of previous inputs rather than just their immediate condition, rendering performance less predictable. In perovskite cells, hysteresis is strictly dependent on the composition of the material. Ion migration and non-radiative recombination near interfaces are generally considered responsible for the effect.

A team of researchers from Mahidol University, Chiang Mai University and PERCH-SIS Institute in Thailand has developed a new precision spray-coating method that enables more complex perovskite solar cell designs and could be scaled up for mass production.

The researchers demonstrated the technique by depositing a perovskite material with higher stability on different perovskite material with better electrical properties. Applying different perovskite materials in each layer can be used to customize a device's properties or meet specific performance and stability requirements.

A UNIST research team has developed an electrode that can significantly improve the stability of perovskite solar cells. UNIST announced that its research team developed 'flexible and transparent metal electrode-based perovskite solar cells with a graphene interlayer'.

The team suppressed interdiffusion and degradation using a graphene material with high impermeability, the team said. Team leader professor Hyesung Park commented that the research will greatly help not only solar cells but other perovskite-based flexible photoelectric devices such as LEDs and smart sensors.