A team of researchers have demonstrated the viability of the direct piezoelectric effect in a thin film Bismuth Ferrite Material for the first time. The work, published in Nanoscale entitles “Direct and Converse Piezoelectric Responses at the Nanoscale from Epitaxial BiFeO3 Thin Films Grown by Polymer Assisted Deposition” which has gained the cover letter of such journal.
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In this particular research, the BFO was scanned in a novel methodology named “Direct Piezoelectric Force Microscopy” DPFM, a new AFM mode invented in 2017
(https://www.nature.com/articles/s41467-017-01361-2 ). The material in this mode is stressed by the AFM tip with nanometric size. The tip applies a force in the range of hundreds of microNewton and measures the generated charge that is created by the material. For the case of BFO material, the piezoelectric characteristics were collected when the tip crosses antiparallel domain configurations, see the following video for a 3D representation of the tip crossing such configuration: https://youtu.be/ir3W2Vk8hCs
The silicon-based tandem solar cell is regarded as the most promising strategy to break the theoretical efficiency limit of single-junction Si solar cells. With Si-based tandem solar cells as the bottom cells, the optimal bandgap of top cells is 1.7 eV, which enables high efficiency of ~45% for two-junction tandem solar cells. III-V semiconductors/Si and perovskites/Si tandem solar cells have achieved high efficiency levels of ~30%, proving their feasibility. However, the stability challenges of perovskite and the high-cost problem of III-V semiconductors largely limit their wide applications. Exploring new stable, low-cost, and bandgap 1.7 eV photovoltaic materials is of great significance in science and broad prospects in technology.
Cadmium selenide (CdSe), a binary II-VI semiconductor, enjoys great potential in the application of Si-based tandemsolar cells because of the suitable bandgap of ~1.7 eV, excellent optoelectronic properties, high stability, and low manufacturing cost. Nevertheless, the progress of CdSe thin-film solar cells remains as it was 30 years ago, and there are few systematic studies on CdSe thin-film solar cells in recent years.
Professor Tang Jiang and his team have proposed a method of rapid thermal evaporation (RTE) to obtain high-quality CdSe thin films and have designed CdSe thin-film solar cells. This study, entitled Rapid thermal evaporation for cadmium selenide thin-film solar cells, was published in Frontiers of Optoelectronics on Dec. 6, 2021.
Easily printable, organic thin films can retain data for more than 10 years without power, work with low voltages – and become the building block of future computers that mimic the human brain
The internet of things is coming, that much we know. But still it won’t; not until we have components and chips that can handle the explosion of data that comes with IoT. In 2020, there will already be 50 billion industrial internet sensors in place all around us. A single autonomous device – a smart watch, a cleaning robot, or a driverless car – can produce gigabytes of data each day, whereas an airbus may have over 10,000 sensors in one wing alone.
Two hurdles need to be overcome. First, current transistors in computer chips must be miniaturized to the size of only few nanometres; the problem is they won’t work anymore then. Second, analysing and storing unprecedented amounts of data will require equally huge amounts of energy. Sayani Majumdar, Academy Fellow at Aalto University, along with her colleagues, is designing technology to tackle both issues.
Majumdar has with her colleagues designed and fabricated the basic building blocks of future components in what are called “neuromorphic” computers inspired by the human brain. It’s a field of research on which the largest ICT companies in the world and also the EU are investing heavily. Still, no one has yet come up with a nano-scale hardware architecture that could be scaled to industrial manufacture and use.
Something New Grows on Trees: Biodegradable Chips for Electronics
It was just a couple of weeks ago when we featured nanocellulose, a natural supermaterial derived from plants that is getting ready for the spotlight. Researchers are looking at it for durable, transparent composites because of its strength. Others are investigating its use in applications from biocompatible implants and flexible displays and solar panels to better bioplastics, cosmetics and concrete.
Now we hear from the University of Wisconsin-Madison and the U.S. Department of Agriculture Forest Products Laboratory that scientists have demonstrated a new product for the nanoscopic fibers of cellulose, a carbohydrate that gives structure to plant cell walls. Turning the material into a film, they’ve been able to produce high-performance computer chips made almost entirely of wood.
By replacing the semiconducting foundation of modern chips with biodegradable nanocellulose, electronics could become significantly less of an environmental burden when they are discarded.
Solar cells have come a long way, but inexpensive, thin film solar cells are still far behind more expensive, crystalline solar cells in efficiency. Now, a team of researchers suggests that using two thin films of different materials may be the way to go to create affordable, thin film cells with about 34% efficiency.
“Ten years ago I knew very little about solar cells, but it became clear to me they were very important,” said Akhlesh Lakhtakia, Evan Pugh University Professor and Charles Godfrey Binder Professor of Engineering Science and Mechanics, Penn State.
Investigating the field, he found that researchers approached solar cells from two sides, the optical side — looking on how the sun’s light is collected — and the electrical side — looking at how the collected sunlight is converted into electricity. Optical researchers strive to optimize light capture, while electrical researchers strive to optimize conversion to electricity, both sides simplifying the other.
“I decided to create a model in which both electrical and optical aspects will be treated equally,” said Lakhtakia. “We needed to increase actual efficiency, because if the efficiency of a cell is less than 30% it isn’t going to make a difference.” The researchers report their results in a recent issue of Applied Physics Letters.
A research team consisting of MANA Independent Scientist Takeo Minari, International Center for Materials Nanoarchitectonics (MANA), NIMS, and Colloidal Ink developed a printing technique for forming electronic circuits and thin-film transistors (TFTs) with line width and line spacing both being 1 μm. Using this technique, the research team formed fully-printed organic TFTs with a channel length of 1 μm on flexible substrates, and confirmed that the TFTs operate at a practical level.
Printed electronics – printing techniques to fabricate electronic devices using functional materials dissolved in ink – is drawing much attention in recent years as a promising new method to create large-area semiconductor devices at low cost. Because these techniques enable the formation of electronic devices even on flexible substrates, they are expected to be applicable to new fields such as wearable devices. In comparison, conventional printing technologies allow the formation of circuits and devices with line widths only as narrow as several dozen micrometers. Accordingly, they are not applicable to the creation of minute devices suitable for practical use. Thus, there were high expectations for developing new printing techniques capable of consistently fabricating circuits with line widths of several micrometers or less.
Single thin-film crystals are required to utilize promising hybrid organic/inorganic perovskite materials to develop solar cells. Saudi Arabia’s King Abdullah University of Science and Technology (KAUST) researchers have now shown how imploding bubbles in a solution can grow single crystals of the preferred orientation for manufacturing thin films.
Hybrid organic/inorganic perovskite materials are some of the most promising solar cell materials, as they are easy to produce and show excellent solar light conversion efficiencies.
“Our monocrystalline films provide a platform to directly implement perovskite single crystals and to elucidate their promises and challenges for solar cells,” said Osman Bakr, KAUST associate professor of material science and engineering who also led the research study.
Hybrid perovskite materials can easily be fabricated on a large scale from a solvent solution. However, this process typically produces polycrystalline perovskite films that have a smaller solar light conversion efficiency than monocrystalline materials because the boundary between crystalline grains leads to losses. In particular, growth of single-crystalline perovskite solar cell films has not yet been achieved on top of other materials, which is a requirement for practical devices.
A selection of evaporation sources in our cleanroom. Evaporation is a thin film deposition technique where the material is heated up to above its melting point in vacuum, typically using an electron beam. The molten material evaporates and is redeposited on your samples which are positioned near the source. Common materials that can be deposited using this technique include gold, copper, titanium, platinum, nickel, iron, silicon dioxide, and carbon.
Sputter deposition is a fabrication technique used to deposit thin films of a particular material onto a sample. The film can then be patterned using lithography into, for example, electrical contacts for your device. It is commonly used in the semiconductor industry to make integrated circuits.
First a gaseous plasma of ions, typically argon, is created in the sputter chamber. Ions in the plasma are then accelerated into a large piece of the material to be deposited, called the target, causing atoms to be ejected from the surface. Atoms that reach the sample or substrate are redeposited, forming a thin film over time.
