May 2018

A research team at the Dalian Institute of Chemical Physics (DICP) of the Chinese Academy of Sciences has fabricated a sensitive photodetector based on lead-free perovskite single crystals.

"We have developed a high performance photodetector based on MA3Sb2I9 microsingle crystals (MSCs)," said Prof. HAN. Scientists found that MA3Sb2I9 single crystals exhibited a low trap-state density of ~1010 cm-3, high carrier mobility of 12.8 cm2 V-1 s-1 and long carrier diffusion length reaching 3.0 μm.

Researchers from the Institute of Physical Chemistry of the Polish Academy of Sciences and the Faculty of Chemistry of Warsaw University of Technology have designed what they consider to be an improved version of a perovskite, containing in the crystal structure a relatively large organic ion, a guanidinium cation. Lab tests at the EPFL have reportedly shown that photovoltaic cells made of the new perovskite work more efficiently than the cells prepared using its original form.

The guanidinium cation was incorporated into the crystal structure of the classic perovskite using a 'solvent-less' mechanochemical approach. The experiments proved that from many aspects the new, modified perovskites are clearly better than the parent (CH3NH3)PbI3.

Oxford University researchers attempted to understand what makes certain combinations of elements in the Periodic Table arrange as perovskite crystals and others not, and whether the number and nature of undiscovered pervoskites can be.

The team examined the Norwegian mineralogist Victor Goldschmidt's 1926 hypothesis known as the 'no-rattling' approach: that the formability of perovskites follows a simple geometric principle, namely: The number of anions surrounding a cation tends to be as large as possible, subject to the condition that all anions touch the cation. It basically means that if we describe a crystal using a model of rigid spheres, in a perovskite the spheres tend to be tightly packed, so that none can move around freely. Using elementary geometry, Goldschmidt's hypothesis can be translated into a set of six simple mathematical rules that must be obeyed by the ions of a perovskite.

Researchers at the Argonne-Northwestern Solar Energy Research Center (ANSER) have developed a new way to protect perovskite-based solar cells from water and stabilize them against heat. By carefully growing an ultrathin layer of metal oxide on a carbon coating, the researchers made a perovskite device that worked even after exposing it to a stream of water.

Solar cells are made up of layers, each with a specific duty. The perovskite layer absorbs sunlight, which can excite an electron. The electron could go back to where it started, unless it can be successfully extracted out of the absorbing layer quickly. For this device, the researchers placed a layer of PC61BM, a carbon-based material, on top of the perovskite, which has two roles.

Researchers at the Japan-based Okinawa Institute of Science and Technology Graduate University (OIST) have developed perovskite-based solar devices using a new perovskite material that is stable, efficient and relatively cheap to produce.

This material has several key features. First, it is completely inorganic ' an important shift, because organic components are usually not thermostable and degrade under heat. Since solar cells can get very hot in the sun, heat stability is crucial. By replacing the organic parts with inorganic materials, the researchers made the perovskite solar cells much more stable. 'The solar cells are almost unchanged after exposure to light for 300 hours,' says Dr. Zonghao Liu, an author on the paper.