Researchers at Duke University computationally predicted the electrical and optical properties of layered hybrid organic-inorganic perovskites (or HOIPs) - popular materials for light-based devices such as solar cells and light-emitting diodes (LEDs). The ability to build accurate models of these materials atom-by-atom will allow researchers to explore new material designs for next-generation devices.

“Ideally we would like to be able to manipulate the organic and inorganic components of these types of materials independently and create semiconductors with new, predictable properties,” said David Mitzi, Professor of Mechanical Engineering and Materials Science at Duke. “This study shows that we are able to match and explain the experimental properties of these materials through complex supercomputer simulations, which is quite exciting.”

Researchers at UvA-IoP have shown that certain perovskites possess the desirable property of carrier multiplication – an effect that makes materials more efficient in converting light into electricity.

Research leaders Dr. Chris de Weerd and Dr. Leyre Gomez explain this property, which had so far not been shown to exist in perovskites. When semiconductors – in solar cells , for example – convert the energy of light into electricity, this is usually done one particle at a time: a single infalling photon results in a single excited electron (and the corresponding ‘hole’ where the electron used to be) that can carry an electrical current. However, in certain materials, if the infalling light is energetic enough, further electron-hole pairs can be excited as a result; it is this process that is known as carrier multiplication.

Researchers at the Adolphe Merkle Institute in Fribourg and the Ecole Polytechnique Fédérale de Lausanne have developed a new technique to replace one of the least stable components in perovskite solar cells, which could be a major step towards commercialization.

Perovskites are seen as promising thin-film solar-cell materials because they can absorb light over a broad range of solar spectrum wavelengths thanks to their tuneable bandgaps. Charge carriers (electrons and holes) can also diffuse through them quickly and over long lengths. The most efficient perovskite solar cells usually contain bromide and MA, which is thermally unstable. To overcome this problem, researchers tried replace MA with FA since it is not only more thermally stable but also has an optimal redshifted bandgap. Unfortunately, because of its large size, FA does distort the perovskite lattice and tends to produce a photoinactive “yellow” phase at room temperature. The other photoactive “black phase” can only be seen at high temperatures. However, the researchers in this new work have now found a way to stabilize the black phase of FA at room temperature.

A next-generation optical material based on perovskite nanoparticles can achieve vivid colors even on very large screens. Due to their high color purity and low cost advantages, it has also gained much interests in industry. A recent study including researchers with UNIST has introduced a simple technique to extract the three primary colors (red, blue, green) from this material.

This innovative work was led by Professor Jin Young Kim in the School of Energy and Chemical Engineering at UNIST. In the study, the research team introduced a simple technique that freely controls light emitting spectra by adjusting the anion halides in perovskite materials. The key is to adjust the anion halides by dissolving them in solvents to achieve red, blue and green lights. Application of this technique to LEDs can result in crystal-clear picture quality.

Researchers at Linköping University and Shenzhen University have shown how inorganic perovskites can be used to produce low-cost and efficient photodetectors that transfer both text and music. "It's a promising material for future rapid optical communication," says Feng Gao, researcher at Linköping University.

"Perovskites of inorganic materials have a huge potential to influence the development of optical communication. These materials have rapid response times, are simple to manufacture, and are extremely stable." says Feng Gao.