Technical / research - Page 60

Scientists from China's Nanjing University and Chinese Academy of Sciences have found that a change to the hole transport layer material helped reduce voltage loss in a perovskite solar cell. The discovery demonstrates a promising new way to overcome a major challenge for perovskites ' particularly those used as the top layer in a tandem device.

The group of scientists noticed that a large part of the problematic voltage loss occurs at the interface between the active perovskite and the hole transport layer (HTL) that helps to carry a charge out of the device, and decided to experiment with alternate materials to try and limit this issue.

Researchers from the U.S. Department of Energy's (DoE) Argonne National Laboratory, Brookhaven National Laboratory, Los Alamos National Laboratory, SLAC National Accelerator Laboratory and Taiwan's Academia Sinica have reported the preparation of stable perovskite nanocrystals for LEDs.

Light-emitting diodes made from perovskite nanocrystals (green) embedded in a metal-organic framework. Image from Phys.org

Perovskite nanocrystals' unstable nature has so far hindered their potential to be used as LED materials. However, the research team managed to stabilize the nanocrystals in a porous structure called a metal-organic framework, or MOF for short. Based on earth-abundant materials and fabricated at room temperature, these LEDs could one day enable lower cost TVs and consumer electronics, as well as better gamma-ray imaging devices and even self-powered X-ray detectors with applications in medicine, security scanning and scientific research.

A joint research team that includes researchers from the Institute of Solid State Chemistry and Mechanochemistry (the Ural Branch of the Russian Academy of Sciences), the Donostia International Physics Centre and the HSE Tikhonov Moscow Institute of Electronics and Mathematics has studied the characteristics of cubic double perovskite oxides.

To date, experimental measurements of the minerals' characteristics have not corresponded to the results of theoretical modeling. In this new work, the researchers set out to better understand this disparity. The data obtained could allow the improvement of low-temperature fuel cell technologies'one of the main alternatives to current sources of electricity.

Researchers from the Australian National University and the University of New South Wales (UNSW) recently used perovskite solar cells for the development of a novel technology for direct solar hydrogen generation (DSTH), claimed to achieve an impressive solar-to-hydrogen efficiency of around 20%.

In DSTH systems, the electricity generated by a PV unit is used to directly drive water-splitting redox reactions without the need for an electrolyzer or complex power infrastructure. Commercial viability, however, remains unattainable despite efficiencies close to 19%, due to the use of expensive semiconductors and noble-metal catalysts.

Researchers from Sungkyunkwan University and Pusan National University recently succeeded in complementing an intrinsic defect of a perovskite solar cell's absorber layer by adding a virus. The team showed that the efficiency of photoelectric transformation improved by using a virus rather than a chemical compound as solar cell thin film.

Solar cells based on perovskites as an absorber layer usually require the addition of a chemical compound due to intrinsic defects of perovskite crystal. Perovskite solar cells are limited as the process of adding chemical compounds is expensive and the purity of the generated material is low.

Researchers from the University of Surrey and the University of Cambridge have examined how two semiconducting materials can satisfy the telecommunication industry's hunger for huge amounts of data at increasing speeds. Light-emitting diode (LED)-based communications techniques allow computing devices, including mobile phones, to communicate with one another by using infrared light. However, LED techniques are underused because in its current state LED transmits data at far slower speeds than other wireless technologies such as light-fidelity (Li-Fi).

The researchers from Surrey and Cambridge, along with partners from the University of Electronic Science and Technology of China, examine how organic semiconductors, colloidal quantum dots (CQDs) and metal halide perovskites, can be used in LED-based optical communications systems.

Researchers from the University of North Carolina have developed a mini perovskite solar module with a power conversion efficiency of up to 19.3% efficiency based on a novel approach for interface engineering.

The new device was created using a new technique for stabilizing the embedded perovskite-substrate interfaces in the solar cells. Common approaches, the researchers explained, had previously focused on stabilizing perovskite-metal electrode interfaces through surface passivation or post-fabrication treatment. 'Degradation of perovskite solar cells starts from the interfaces, including both perovskite-metal electrodes and perovskites-substrates, where defects enrich,' the team stated in the new paper. 'Stabilizing the embedded bottom interfaces is as important as that of [the] top interface.'

Researchers from National Taiwan Normal University and Kyushu University have developed a new memory device, readable through both electrical and optical methods, that needs only perovskites to simultaneously store and visually transmit data.

Schematic of the CsPbBr3 QD-based LEM device. Image from Nature Communications

By integrating a light-emitting electrochemical cell with a resistive random-access memory that are both based on perovskite, the team achieved parallel and synchronous reading of data both electrically and optically in a 'light-emitting memory.'

A University of Toronto research team used the Canadian Light Source (CLS) at the University of Saskatchewan to get a glimpse of the never-before-seen transformation of a 3D crystal into a high efficiency solar cell material.

'There were lots of high fives when we actually looked at the computer screen and could see the reaction in real time,' said Sam Teale, a PhD student at the U of T and co-author on a paper describing the perovskite solar cell research. What the researchers saw, over the course of just three seconds, was the creation of an ultra-thin 2D layer of perovskite on top of a 3D perovskite crystal.

Researchers at KAUST have developed a multifunctional molecule that can plug various atomic-scale defects in perovskite solar materials, which could significantly boost the longevity and electrical output PSCs.

Perovskites inevitably feature defects, such as where a particular ion did not slot into place during fabrication, leaving a gap in the structure. These reactive sites can contribute to rapid performance decline — unless they can be fixed. “Defect passivation is very important for improving the long-term stability of perovskite solar cells,” says Furkan Isikgor, a researcher in Stefaan De Wolf’s group.