Technical / research

Researchers from the University of Surrey, the University of Warwick and the University of New South Wales have reported a nanoscale “ink” coating of aluminum oxide on metal halide perovskite, that stabilizes the drop in energy output that presently plagues perovskite technology.

"In the past, metal oxides have been shown to either benefit or degrade the performance of perovskite solar cells. We’ve identified aluminum oxide which can improve performance and minimize the drop in efficiency during conditioning of perovskite solar cells", said Hashini Perera, Study Lead Author, University of Surrey.

A research team at the Fraunhofer Institute for Solar Energy Systems ISE has reported a perovskite/perovskite/silicon triple-junction solar cell with an open circuit voltage of >2.8 V, which is said to be the record value reported for this structure so far. The Fraunhofer team showed that perovskite-perovskite-silicon subcells can hold considerable promise and have an even greater efficiency potential than double-junction tandem cells.

The triple-junction solar cell was developed as part of the Triumph research project funded by the European Commission and the RIESEN research project funded by the German Federal Ministry for Economic Affairs and Climate Action. This achievement confirms that the cell has excellent material properties for generating electricity, leading the scientists to deduce that it has an efficient solar cell architecture.

Researchers from the East China University of Science and Technology have developed a new manufacturing process to fabricate printable mesoscopic perovskite solar cells (p-MPSCs). The scientists report that the new technique is able to overcome the typical challenges posed by this cell technology, namely their interfacial passivation and layered assembly.

Mesoscopic PV devices are commonly designed with an absorber layer that can be conducted by a solution-based approach and non-vacuum processing, which makes their production costs relatively lower than those of conventional solar cells. Using organic-inorganic layer structured perovskites has recently enabled scientists across to world to reach efficiencies of over 10%.

Researchers from Pohang University of Science and Technology (POSTECH), Chinese Academy of Sciences (CAS) and University of Electronic Science and Technology of China have developed perovskite transistors through the use of three distinct perovskite cation processes. 

The team showed that pure-tin perovskite thin-film transistors can be created using triple A cations of caesium–formamidinium–phenethylammonium. This approach reportedly leads to high-quality cascaded tin perovskite channel films with low-defect, phase-pure perovskite/dielectric interfaces.

Researchers from Japan's Tohoku University and University of Tsukuba have reported a breakthrough in the development of non-volatile phase change memory−a type of electronic memory that can store data even when the power is turned off−using a perovskite-derivative nickelate material.

Until now, phase change memory has primarily been developed using chalcogenides, a group of materials known to exhibit reversible electrical changes when they transition between their crystalline and amorphous states. However, in their recent study, the researchers reported thermally reversible switching of room-temperature electrical resistivity in a layered nickelate−potentially offering better performance and superior sustainability.

Researchers from the University of Toronto, Peking University and Soochow University have studied the origins of unwanted emission in monolayer perovskite LEDs when the active layer thickness approaches ~5 nm and found that using available fabrication techniques results in a rough perovskite/HTL interface which leads to punch-through and direct electrical interaction between HTL and ETL (electron-transporting layer), and consequently, to undesired exciplex emission in LEDs.

The team sought to control monolayer interfaces in Rec.2100 primary blue perovskite LEDs and recognized that a well-defined, ordered, and compact monolayer film could suppress HTL/ETL interaction. They reasoned that this could be achieved if they could alter the polarity of the CsPbBr₃ c-NC surface and thereby induce perovskite self-assembly down to the monolayer limit [i.e., self-assembled monolayer (SAM)] through the use of an HTL-compatible ligand. Self-assembled films with ordered nanocrystal arrangement maximize the interactions between nanocrystals and provide homogeneity needed for monolayer films with ~5-nm thickness.

Researchers from the Indian Institute of Technology Bombay and Germany's Helmholtz Young Investigator Group FRONTRUNNER IEK5-Photovoltaik have designed an inverted perovskite solar device that uses a self-assembled monolayer to suppress nonradiative recombination at the interface between the perovskite absorber and the hole transport layer. The team reported high efficiency for the cell and say it was also able to retain the initial efficiency rating for 3,000 h.

The inverted perovskite solar cell was based on a hole transport layer (HTL) made of a phosphonic acid called methyl-substituted carbazole (Me-4PACz).

Researchers from Linköping University in Sweden and Universidad de Concepción in Chile recently designed a new type of random number generator for encryption, based on Perovskiye LEDs. The new technology could make digital information exchange safer, cheaper and more environmentally friendly and even pave the way for a new type of quantum communication.

To encrypt information, a random number generator is used, which can either be a computer program or the hardware itself. The random number generator provides keys that are used to both encrypt and unlock the information at the receiving end. Different types of random number generators provide different levels of randomness and thus security. Hardware is the safer option as randomness is controlled by physical processes. And the hardware method that provides the best randomness is based on quantum phenomena – what researchers call the Quantum Random Number Generator, QRNG.

Researchers from Duke University, Purdue University,  Yale University, Lawrence Berkeley National Laboratory, Chinese Academy of Sciences (CAS), Westlake University and Huazhong University of Science and Technology have demonstrated that by limiting the arrangement of multiple inorganic and organic layers within crystals using a novel technique, they can regulate the energy levels of electrons and holes (positive charge carriers) within perovskites.

This tuning capability affects the materials’ optoelectronic properties and capacity to emit light of specific energies, as illustrated by their ability to function as a laser source.

Researchers from Japan's Tokyo Institute of Technology, University of Oxford in the UK and Colorado State University in the U.S have shown that α-FAPbI₃, a promising solar cell material with a cubic perovskite structure that is metastable at room temperature, can be stabilized by introducing a pseudo-halide ion like thiocyanate (SCN^–) into its structure. The recent findings provide new insights into the stabilization of the α-phase via grain boundary and pseudo-halide engineering.

A material with good photophysical properties that has recently gained momentum is α-formamidinium lead iodide or α-FAPbI₃ (where FA⁺ = CH(NH₂)₂⁺), a crystalline solid with a cubic perovskite structure. Solar cells made of α-FAPbI₃ exhibit a remarkable 25.8% conversion efficiency and an energy gap of 1.48 eV. Unfortunately, α-FAPbI₃ is metastable at room temperature and undergoes a phase transition to δ-FAPbI₃ when triggered by water or light. The energy gap of δ-FAPbI₃ is much larger than the ideal value for solar cell applications, making the preservation of the α-phase crucial for practical purposes. To overcome this problem, the team of researchers, led by Associate Professor Takafumi Yamamoto from Tokyo Institute of Technology (Tokyo Tech), has recently presented a new strategy for stabilizing α-FAPbI₃.