Perovskites and graphene - Page 3

A research team led by Juan Casanova and Eduard Llobet from the Departamento de Ingeniería Electrónica, Eléctrica y Automática at the Universitat Politècnica de València (URV), used graphene and perovskites to create a nanosensor that detects nitrogen dioxide with 300% improved sensitivity.

The team used graphene that is hydrophobic (water and moisture-resistant) and sensitive in gas detection, but with some limitations: it is not very selective and its sensitivity declines over time. In addition, the researchers used perovskites, a crystalline-structure material commonly used in the field of solar cells. However, they quickly deteriorate when they are exposed to the atmosphere. That's the reason why the team decided to combine perovskites with a hydrophobic material able to repel water molecules - in order to prove they can prevent or slow down their deterioration.

Italian researchers from two Italian institutions claim to have developed a two-terminal tandem perovskite-silicon solar cell with a conversion efficiency 26.3%.

The researchers added graphene to the titanium dioxide electron selective layer used in a perovskite solar cell to increase chemical stability. The two-terminal cell was made by stacking two sub-cells which were fabricated and optimized separately. The new device blends the advantages of thin-film perovskite and silicon-based heterojunction cells, according to its developers.

University of Central Florida researchers are helping to close the gap separating human and machine minds, using a technology based on perovskite quantum dots. In a recent study, a UCF research team showed that by combining two promising nanomaterials into a new superstructure, they could create a nanoscale device that mimics the neural pathways of brain cells used for human vision.

"This is a baby step toward developing neuromorphic computers, which are computer processors that can simultaneously process and memorize information," said Jayan Thomas, an associate professor in UCF's NanoScience Technology Center and Department of Materials Science and Engineering. "This can reduce the processing time as well as the energy required for processing. At some time in the future, this invention may help to make robots that can think like humans."

Several research institutions in South Korea are actively conducting research and development on next-generation solar cells, heightening expectations for commercialization. The research team led by Prof. Yoon Soon-gil of Chungnam National University has developed a new graphene electrode to produce perovskite solar cells at a low temperature. In addition, the team led by Prof. Choi Kyoung-jin of the School of Materials Science and Engineering at UNIST has developed a new concept tandem solar cell using transparent conductive adhesives (TCA).

The graphene electrode developed by Professor Yoon's team can help create a perovskite solar cell at a low temperature and can raise both safety and economic efficiency.

Researchers from the Graphene Flagship have managed to increase the stability of perovskite solar cells (PSCs) using hybrids of graphene and molybdenum disulphide quantum dots.

The team used molybdenum disulphide quantum dot/graphene hybrids to address PSCs' instability issue. The collaboration between research institutions and industrial partners enabled by Graphene Flagship, yielded an ink based on graphene and related materials (GRMs). Layering this over the PSCs caused them to drastically increase in stability.

Emberion researchers have shown that colloidal quantum dots (QDs) combined with a graphene charge transducer can provide a photoconducting platform with high quantum efficiency and large intrinsic gain, yet compatible with cost-efficient polymer substrates. The team demonstrated methods to couple large QDs (>6 nm in diameter) with organometal halide perovskites, enabling hybrid graphene photo-transistor arrays on plastic foils.

The resulting arrays simultaneously exhibited a specific detectivity of 5 × 1012 Jones and high video-frame-rate performance. PbI2 and CH3NH3I co-mediated ligand exchange in PbS QDs improved surface passivation and facilitated electronic transport, yielding faster charge recovery, whereas PbS QDs embedded into a CH3NH3PbI3 matrix produce spatially separated photocarriers leading to large gain.

Researchers from Italy's University of Florence have found that graphene could significantly improve the efficiency of perovskite solar cells. The researchers have shown how the introduction of graphene and graphene oxide doped with lithium atoms (GO-Li) into a perovskite-based cell may increase its conversion efficiency, as both the carrier recombination dynamics and the defect density of the perovskite are considerably improved.

The scientists used graphene doped mesoporous TiO2 (G+mTiO2) with the addition of a lithium-neutralized graphene oxide (GO-Li) interlayer as ETL. They found that the carrier collection efficiency is increased by about a factor two with respect to standard mTiO2.

Researchers from Sun Yat-Sen University in China have created a composite of perovskite quantum dots and graphene oxide that can reduce CO₂ when stimulated with light. It is referred to as the first known example of artificial photosynthesis based on perovskite quantum dots.

The team prepared quantum dots ' semiconductor nanoparticles ' of a highly stable cesium'lead halide perovskite, as well as a composite material made of these quantum dots and graphene oxide. Both materials showed an efficient absorption of visible light and strong luminescence. The team used these products to achieve a fundamental step in artificial photosynthesis ' the reduction of CO₂. To simulate sunlight, they used a xenon lamp with an appropriate filter.

Researchers at the Centre for Hybrid and Organic Solar Energy (CHOSE) of the University of Rome 'Tor Vergata', along with researchers at the Italian Institute of Technology (IIT) and the University of Applied Sciences in Crete (TEI), have stated that they set a new record for conversion efficiency of a perovskite photovoltaic module with an area larger than 50 cm2.

The success was achieved as part of Graphene Flagship, the 1 billion euro European project that promotes graphene-based innovation in sectors like energy, electronics, technology and medicine. Perovskites photovoltaic modules' efficiency is usually demonstrated in the laboratory on cells less than 1 cm2 in size, whereas the new test was performed on modules with an area larger than 50 cm2. The electronic and chemical properties offered by graphene have made it possible to overcome the many difficulties related to the realization of large-area perovskite solar panels.