Berkeley team creates perovskite blue LED and illustrates both limitations and potential of perovskite semiconductors

University of California, Berkeley, scientists have created a blue light-emitting diode (LED) from halide perovskites, overcoming a major barrier to using these cheap, easy-to-make materials in electronic devices.

In the process, however, the researchers discovered a fundamental property of halide perovskites that may prove a barrier to their widespread use as solar cells and transistors. Alternatively, this unique property may open up a whole new world for perovskites far beyond that of today's standard semiconductors.

HZB-led team finds that plants absorb more lead from perovskite solar cells than expected

Researchers led by Prof. Antonio Abate at the Helmholtz-Zentrum Berlin have designed a study to investigate lead hazards relating to perovskite soar cells. They cooperated with plant scientists from the Fujian Agriculture and Forestry University, China, where the experiments were carried out, and with a group from the university of Naples, Italy.

Comparison of mint plants grown on control and PSC soils imageMint plants grown on control soil (left) and perovskite-contaminated soil (right). Credit: Nature

The plant experts prepared contaminated soil samples with different concentrations of lead from either perovskite solar cells or other lead sources and cultivated different plants. After a growth period, they analyzed the lead content in leaves and other parts of the plant. They found that lead from perovskite solar cells is 10 times more bioavailable than lead from other industrial sources.

Strain may enable better perovskite solar cells

Researchers from the University of California San Diego, King Abdullah University of Science and Technology and the Air Force Research Laboratory have developed a technique that could enable the fabrication of longer-lasting and more efficient perovskite solar cells, photodetectors, and LEDs.

Strain-engineered, single crystal thin film of perovskite imageStrain-engineered, single crystal thin film of perovskite grown on a series of substrates with varying compositions and lattice sizes. Image Credit: David Baillot/UC San Diego Jacobs School of Engineering.

A major obstacle is the tendency of one of the best-performing perovskite crystals, α-formamidinium lead iodide (HC(NH2)2PbI3, known as α-FAPbI3), to assume a hexagonal structure at room temperature, in which photovoltaic devices are required to operate. This hexagonal structure cannot respond to most of the frequencies of light in solar radiation, and is hence not useful for solar applications as it could be. The team therefore set out to stabilize the structure of α-FAPbI3, using a simple but useful approach known as strain engineering, which has been used to tune the electronic properties of semiconductors.

Japanese manufacturer acquires rights to produce CIGS perovskite cell with 23.26% efficiency developed by HZB and Kaunas University

In September 2019, a research team led by Prof. Steve Albrecht from the HZB (in close collaboration with Kaunas University of Technology in Lithuania) announced a tandem solar cell with certified efficiency of 23.26% that combines the semiconducting materials perovskite and CIGS. Now, the team shares further details on these cells and states that an unnamed Japanese manufacturer has acquired the rights to produce them.

World record for tandem perovskite-CIGS solar cell image

The scientists said the self-assembling material used for the cell is made of molecules based on carbazole head groups with phosphonic acid anchoring groups, and consists of 1-2nm of self-assembled monolayers deposited on the surface of the perovskite by dipping it into a diluted solution.

EPFL team reports on new method to enable rapid and stable production of perovskite solar cells

Researchers at EPFL in Switzerland have reported on the use of Flash Infrared Annealing (FIRA) to rapidly produce efficient, stable perovskite solar cells.

FIRA shares many characteristics with thermal annealing techniques already used to grow pure crystal phases for the semiconductor industry. It works by using a short IR pulse to rapidly nucleate a perovskite film from a precursor solution, without the need for a high-temperature scaffold. The high speed and relatively low processing temperatures mean that FIRA is compatible with large-area deposition techniques, like roll-to-roll processing. For PSCs, it could offer a practical route to scaling-up production.