Penn State researchers have found a new class of 2D perovskite materials with edges that are conductive like metals and cores that are insulating. The researchers said these unique properties may have applications in solar cells and nanoelectronics.

“This observation of the metal-like conductive states at the layer edges of these 2D perovskite materials provides a new way to improve the performance of next-generation optoelectronics and develop innovative nanoelectronics,” said Kai Wang, assistant research professor in materials science and engineering at Penn State and lead author on the study.

Scientists at Linköping University (LiU), along with colleagues from China, have shown how to achieve efficient perovskite light-emitting diodes (LEDs). The researchers provide guidelines on fabricating high-quality perovskite light emitters, and consequently high-efficiency perovskite LEDs.

Different metal oxide layers affect the properties of the thin perovskite films. Credit: Charlotte Perhammar

The halide perovskites can be easily prepared by low-cost solution processing from precursor solution comprising metal halides and organic halides. The resulting perovskites reportedly possess excellent optical and electrical properties, making them promising candidates for various kinds of optoelectronic devices, such as solar cells, LEDs and photodetectors.

Scientists at Germany's Karlsruhe Institute of Technology (KIT) and the Innovation Lab in Heidelberg have developed a highly efficient hole conductor layer made of nickel oxide (NiOx) that can be deposited over a large area and leads to record efficiencies in solar cells with organometallic perovskites.

The team achieved efficiencies of up to 16.1% for completely vacuum-processed perovskite solar cells. With inkjet-printed absorber layers, the scientists achieved an efficiency record of up to 18.5%. "Currently, deposition by rotary coating, for which efficiencies of more than 24% have been achieved, dominates development. However, this can practically not be transferred to large areas" says Tobias Abzieher, PhD student at KIT's Light Technology Institute (LTI).

Researchers at the Dalian Institute of Chemical Physics at the Chinese Academy of Science have reported a series of bulk lead-free double perovskites which demonstrate the existence of parity-forbidden transition by photophysical characterization in Cs₂AgInCl₆ bulk crystal. The perovskites break the parity-forbidden transition and show warm white-light emission with broad emission across the entire visible spectrum, with the highest PLQE of 70.3%.

The luminescence property of Cs2AgBi1-xInxCl6 (0 < x < 1) varied with increasing In content; the crystal structure of Cs2AgBi0.125In0.875Cl6 bulk crystal. Credit: Science China Press

The synthesized nanocrystals and microcrystals revealed that the PLQE decreases with the size decreasing, due to the enhancement of the PL quenching effect, caused by the increase of permanent defects. Furthermore, the Cs₂AgBi_0.125In_0.875Cl₆ bulk crystal possesses excellent stability. Therefore, it's promising as a new highly efficient warm white-light emitting material in LED applications.