A research team consisting of scholars from Sweden, UK, China and the Czech has developed a perovskite LED with both high efficiency and long operational stability. The result has been published in Nature Communications, titled “Perovskite-molecule composite thin films for efficient and stable light-emitting diodes.”

Perovskites are a large family of semiconducting materials that have aroused the interest of scientists around the world. Their special crystal structure means that they have excellent optical and electronic properties, while they are both easy and cheap to manufacture. Most progress has been made in research into the use of perovskites in solar cells, but they are also well-suited for the manufacture of LEDs.

The efficiency of the LEDs, which measures the fraction of charge carriers input to the material that are subsequently emitted as light, has increased considerably in recent years, and will soon reach that of competing technology. They are, however, not particularly stable, which means that so far they cannot be used in practice.

(Heyong Wang, co-author, Ph.D. student at Linköping University; image LiU)

The researchers used a perovskite that consists of lead, iodine and an organic substance, formamidinium. They have then embedded the perovskite into an organic molecule matrix to form a composite thin film. According to the team, the molecule with two amino groups at its ends helps the other substances to form a high quality crystal structure that is characteristic for perovskites, and makes the crystal stable.

The new composite thin film has enabled the research group to develop LEDs with an efficiency of 17.3% with a long half-lifetime, approximately 100 hours.

The next steps are to test new combinations of different perovskites and organic molecules and to understand in detail how the nucleation and crystallisation processes occur. Different perovskites give light at different wavelengths, which is a requirement for the long-term goal of obtaining white light LEDs.

Original source: https://liu.se/en/news-item/ett-steg-narmare-en-stabil-lysdiod-i-perovskit