February 2018

New research by teams at Inha University and Chonnam National University in South Korea reveals how to improve the lifetime of perovskite-based solar cells. The team has developed a method known as co-precipitation to make a thin film comprising nanoporous nickel oxide as the hole transporting layer (HTL) for a perovskite solar cell that uses the unique composition of FAPbI3 and or MAPbBr3 as the perovskite layer. In addition, they used an organic air-stable inorganic zinc oxide nanoparticles compound as the ETL (electron transporting layer) in order to protect the perovskite layer from air.

"We successfully optimized the metal oxide based HTL and ETL protecting layers for highly efficient perovskite absorber by a simple method which can make air-stable photovoltaics," explains co-author of the study. "Our main goal is to solve the problem of the tedious process of making conventional additive-doped, highly expensive, unstable HTLs by replacing low-cost, inorganic air-stable p and n-type metal oxides," he added.

scientists at the University of Warwick, Oxford University, University of Cambridge, Los Alamos National Laboratory and University at Buffalo in the U.S have found a colossal magnetoresistance at terahertz frequencies at room temperature in high-quality functional perovskite-based nanocomposites. This may find use in nanoelectronics and in THz optical components controlled by magnetic fields.

Electronics that can read and write data at terahertz frequency, rather than at a few gigahertz, can lead to faster performance. Creating such devices would be aided by the use of materials that can undergo a huge change in how easily they conduct electricity in response to a magnetic field at room temperature. Scientists believe thin films of perovskite oxides hold promise for such uses, but such behavior has until now never been seen at these frequencies in these films.

Researchers at Brown University and University of Nebraska - Lincoln (UNL) have come up with a new titanium-based material for making lead-free, inorganic perovskite solar cells. The team shows that the material has significant potential, especially for making tandem solar cells.

"Titanium is an abundant, robust and biocompatible element that, until now, has been largely overlooked in perovskite research," said the senior author of the new paper. "We showed that it's possible to use titanium-based material to make thin-film perovskites and that the material has favorable properties for solar applications which can be tuned."

A recent report by Cintelliq on the perovskite solar cell patent landscape shows massive growth in perovskite photovoltaic patent publications over the past two years. In 2016 and 2017 more than 1500 patents have been published representing 75% of all perovskite photovoltaic patents published since 2008.

The total number of patents published to the end of December 2017 is 2030 and filed by 396 distinct assignees. These published patents arise from innovations that occurred in previous years, as can be seen in the chart of yearly patent filed and published. As can also be seen there are fewer patent filings in 2016 and even less in 2017. However, this is not a rapid fall in filings, but a probable side effect of the length of time it takes to go from initial filing through to initial publications.

A team of researchers at Northwestern University has created a new fuel cell with a perovskite-based cathode, that offers both exceptional power densities and long-term stability at optimal temperatures.

"For years, industry has told us that the holy grail is getting fuel cells to work at 500-degrees Celsius and with high power density, which means a longer life and less expensive components," said the team. "With this research, we can now envision a path to making cost-effective fuel cells and transforming the energy landscape."

Researchers from the Russian ITMO University have developed effective nanoscale light sources based on a halide perovskite. These nanosources are subwavelength nanoparticles which serve both as emitters and nanoantennas and allow enhancing light emission inherently without additional devices. Moreover, the perovskite enables tuning the emission spectra throughout a visible range by varying the composition of the material. The new nanoparticles are a promising platform for creating compact optoelectronic devices such as optical chips, light-emitting diodes, or sensors.

The nanoscale light sources and nanoantennas have already found a wide range of applications in several areas, such as ultra compact pixels, optical detection, or telecommunications. However, the fabrication of nanostructure-based devices is rather complicated due to the limited luminescence efficiency of the materials used typically as well as non-directional and relatively weak light emission of single quantum dots or molecules. An even more challenging task is placing a nanoscale light source precisely near a nanoantenna.

CHEOPS, a European research project with a focus on upscaling perovskite photovoltaic cells, has released a new research that shows a way to reduce the 'dead area' of photovoltaic cells by applying an enhanced laser patterning process. This new development means that more of the area of a cell can be used for energy conversion, making it more efficient.

For upscaling efforts to achieve suitable currents, photovoltaic cells are usually split into a series of interconnected segments. It is these breaks in the material that need to be made as small as possible to be able to optimize the cell for energy conversion. This so-called 'dead area' has been reduced to a width of 400μm by using a new laser patterning process.

Researchers at Aalto University have found that only a fraction of stability tests done on perovskite-based solar cells and dye-sensitized solar cells meet proper requirements. The team analyzed 261 aging tests conducted on such solar and saw major shortcomings in both how the results had been reported and how tests had been implemented. Tests lack common standards and should have been done in real-world conditions and in groups of several cells.

"In about half of the aging studies, the data was published only for one solar cell. Studying only one cell does not yield a sufficient amount of data to reliably compare how different materials age, that is, lose efficiency over time," says the team.

A study by EPFL researchers Michael Grätzel and Amita Ummadisingu offers valuable insight into the sequential deposition reaction. This process, used as one of the main methods for depositing perovskite films onto panel structures, was developed in 2013 by Michael Grätzel and co-workers at EPFL. Many studies have since tried to control this process with additives, compositional changes, and temperature effects, but none of these has provided a complete understanding of the entire sequential deposition reaction. This prevents adequate control over film quality, which determines the performance of the solar cell.

The EPFL scientists began with X-ray diffraction analysis and scanning electron microscopy to study in depth the crystallization of lead iodide (PbI2), which is the first stage of the reaction. They then used, for the first time, SEM-cathodoluminescence imaging to study the nano-scale dynamics of perovskite film formation.

Researchers at the U.S. Naval Research Laboratory (NRL) Center for Computational Materials Science, working with an international team of physicists, have found that nanocrystals made of cesium lead halide perovskites (CsPbX3), is the first discovered material which the ground exciton state is "bright," making it an attractive candidate for more efficient solid-state lasers and light emitting diodes (LEDs).

The work focused on lead halide perovskites with three different compositions, including chlorine, bromine, and iodine. Nanocrystals made of these compounds and their alloys can be tuned to emit light at wavelengths that span the entire visible range, while retaining the fast light emission that gives them their superior performance.