Perovskites and graphene
Perovskites are materials that share a crystal structure similar to the mineral called perovskite, which consists of calcium titanium oxide (CaTiO3).
Depending on which atoms/molecules are used in the structure, perovskites can possess an impressive array of interesting properties including superconductivity, ferroelectricity, charge ordering, spin dependent transport and much more. Perovskites therefore hold exciting opportunities for physicists, chemists and material scientists.
Graphene is a one-atom-thick layer of carbon atoms arranged in a hexagonal lattice. It is the building-block of Graphite (which is used, among others things, in pencil tips), but graphene is a remarkable substance on its own - with a multitude of astonishing properties which repeatedly earn it the title “wonder material”. Graphene is the thinnest material known to man at one atom thick, and also incredibly strong - about 200 times stronger than steel. On top of that, graphene is an excellent conductor of heat and electricity and has interesting light absorption abilities. These varied properties make it a promising and highly researched material, with hopes of incorporating it in many applications: from inks and composite materials, through sensors, solar cells and water filters, to batteries and supercapacitors.
Due to their unique properties, carbon-based nanomaterials have been the center of extensive research efforts in various fields, one of which is the field of photovoltaic energy conversion. In recent years, hybrid metalorganic halide perovskites have become one of the most promising materials for third generation solar cells, with efficiencies that are constantly on the rise.
The incorporation of graphene into perovskite-based solar cells was naturally proposed, and significant work is taking place on this matter. Graphene-based perovskite solar cells are studied in many ways, including hole and electron transport media (HTM and ETM), electrodes, and various approaches aiming at improving the stability of the device. Tandem architectures based on graphene interlayers are also of great interest.
In addition to solar cells, other areas of graphene and perovskite integration include sensors and photodetectors, QDs, nanocatalysts and more.
Researchers present new method for fabricating thin films of perovskite oxide semiconductors
Researchers from the University of Minnesota Twin Cities-led, University of Wisconsin–Madison and Pacific Northwest National Laboratory have developed a new method for making thin films of perovskite oxide semiconductors, a class of “smart” materials with unique properties that can change in response to stimuli like light, magnetic fields, or electric fields.
Their work could allow researchers to harness these properties and even combine them with other emerging nano-scale materials to make better devices such as sensors, smart textiles, and flexible electronics.
Researchers examine how molybdenum ditelluride could increase carrier generation in perovskite solar cells
Researchers from South Korea's Sungkyunkwan University (SKKU) have found that molybdenum ditelluride could increase carrier generation in perovskite solar cells.
They simulated a tandem solar cell with two absorbers based on methylammonium lead triiodide (CH3NH3PbI3) – a perovskite with high photoluminescence quantum yield – and molybdenum ditelluride (MoTe2), which is known for being naturally p-doped, with cascaded bandgaps to absorb a wider solar spectrum. The team determined that its efficiency could exceed 20%.
Researchers design graphene oxide/silicon heterojunction solar cell with 18.8% efficiency
Researchers from Hebei University, Karlsruhe Institute of Technology and Chinese module manufacturer Yingli Green Energy Holding Co. Ltd. have reported a heterojunction solar cell based on graphene-oxide (GO) and silicon with a large area of 5.5 cm2.
GO is a compound of carbon, oxygen and hydrogen that is obtained by treating graphite with oxidizers and acids. It consists of a single-layer sheet of graphite oxide that is commonly used to produce graphene-related nanomaterials for various applications, including electronics, optics, chemistry and more. The scientists developed an ink made of GO mixed with Nafion, that can be spin-coated on an n-type silicon wafer to form a high-quality passivating contact scheme. “Low interface recombination is provided by the Nafion and carrier selection by the GO,” the team explained, noting that the passivation scheme also includes an electron-selective passivation contact comprising n-doped hydrogenated amorphous silicon with an indium tin oxide (ITO) overlayer aimed at improving light trapping and reducing surface recombination.
Researchers integrate large-area graphene-perovskite solar panels into stand-alone solar farm
An international research group, including teams from CHOSE at the University of Rome Tor Vergata, Hellenic Mediterranean University in Greece and others, has developed a large-area perovskite solar panel with graphene-doped electron transporting layers (ETLs) and functionalized molybdenum disulfide (fMoS2) buffer layers inserted between the perovskite layer and the hole transporting layer (HTL).
The team reported that with increasing temperatures, the module exhibited a smaller drop in open-circuit voltage than commercially available crystalline silicon panels.
Researchers demonstrate how graphene can improve perovskite solar cells
Recent research has shown that the incorporation of graphene-related materials improves the performance and stability of perovskite solar cells. Graphene is hydrophobic, which can enhance several properties of perovskite solar cells. Firstly, it can enhance stability and the passivation of electron traps at the perovskite's crystalline domain interfaces. Graphene can also provide better energy level alignment, leading to more efficient devices.
In a recent study, Spain-based scientists used pristine graphene to improve the properties of MAPbI3, a popular perovskite material. Pristine graphene was combined with the metal halide perovskite to form the active layer of the solar cells. By analyzing the resulting graphene/perovskite material, it was observed that an average efficiency value of 15% under high-stress conditions was achieved when the optimal amount of graphene was used.
Graphene Flagship's GRAPES project to promote graphene-enabled perovskite solar panels
The Graphene Flagship, a $1 billion European graphene initiative, has launched a new Spearhead Project called GRAPES, that aims to make cost-effective, stable graphene-enabled perovskite solar panels.
The project will set out to play an essential role in improving Europe's uptake of solar energy projects by improving the stability and efficiency of this technology when deployed on a large scale. As a European Commission funded project, the Graphene Flagship GRAPES initiative has been established to help Europe meet its ambitious sustainability goals.
A new method overcomes the drawback of perovskite grain boundaries by using 2D materials for conducting hole currents
A team of scientists, led by Professor Feng Yan from Department of Applied Physics, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, and co-workers, recentky developed a novel method to overcome the drawback of grain boundaries (GBs) in perovskites without using defect passivation.
Several 2D materials, including black phosphorus (BP), MoS2 and graphene oxide (GO), were specifically modified on the edge of perovskite GBs by a solution process. The 2D materials have high carrier mobilities, ultrathin thicknesses and smooth surfaces without dangling bonds. The PCEs of the devices are substantially enhanced by the 2D flakes, in which BP flakes can induce the highest relative enhancement of about 15%.
Researchers reach excellent results on air processed methylammonium free PSCs via scalable technique
A research team, led by Dr. Luigi Angelo Castriotta at the at University of Rome Tor Vergata's CHOSE Center for Hybrid and Organic Solar Energy, has reported impressive results on methylammonium free perovskites processed in air, using a scalable technique based on infrared annealing and potassium doped graphene oxide as an interlayer.
The team reached efficiencies of 18.3% and 16.10% on 0.1cm2 cell and on 16cm2 module respectively, with enhanced stability compares to the standard multi cation reference.
Researchers design novel X-ray photodetectors based on perovskites on top of graphene
A team of scientists, led by László Forró from the School of Basic Sciences at the Ecole Polytechnique Federale de Lausanne (EPFL) in Switzerland, has developed a new X-Ray Photodetector based on perovskites and graphene.
Using 3D aerosol jet-printing technology, the team designed a new technique for creating highly efficient x-ray photodetectors that can be easily added to standard microelectronic circuits, creating more powerful medical imaging devices that can deliver better scan qualities.
Graphene-perovskite solar farm trial up and running in Greece
An experimental graphene-based perovskite solar farm has been operating in Greece for several months, and early results are said to be very promising when it comes to power output and efficiency.
Located at the Hellenic Mediterranean University in Crete and spearheaded by the EU's Graphene Flagship, the new solar farm consists of nine graphene'perovskite panels with a total area of 4.5m2 and a total output of approximately 261 watt-peak (Wp).
