爆走黑料

Gold (I) halides form tetragonal structures similar to chains, where the bond between the individual chains is provided by the so-called aurophilic interaction which is very weak by its nature. Because of this feature, such materials have relatively low melting points (~100–150 °C). But they have a fairly narrow range of applications and are still considered understudied. However, a fundamental knowledge of the properties of the material often helps to look for ways to improve its stability. This was the case, for example, of (phosphorene) which was obtained in 2014.

“We found that making a two-dimensional material from gold halide crystals is energetically no more difficult than making graphene from graphite. According to the analysis, new 2D materials should be kinetically and thermodynamically stable. The unique structure of gold halides makes them quite difficult to calculate and requires the use of high-precision analysis methods,” said Artyom Kuklin, senior researcher at the SibFU Research Center.

To study the optical properties of new compounds, the scientists have applied high-level methods for calculating the quasiparticle electronic structure, taking into account the formation of electron-hole pairs (excitons). It appeared that the compounds manifest characteristic absorption of photons in the ultraviolet. However, the formation of excitons with high binding energies significantly broadens the light absorption spectrum towards the red range. The high binding energy of excitons and optical bandgaps of ~2 eV suggest that two-dimensional gold halides are good candidates for studying new optoelectronic phenomena.

“We expect that 2D AuBr and AuI can also show interesting nonlinear optical properties due to their inherent structural features. These materials have a significant spin-orbit effect arising from weakly bound valence s and p electrons — this makes such materials unique. We found out that this effect is significantly stronger than in pure gold and similar gold chalcogenides. Given the tremendous pace of development of two-dimensional materials, we expect that two-dimensional gold halides can be synthesized in the coming 2–3 years. Such materials will likely find application in optoelectronics as transistors, photodetectors, photodiodes,” Artyom Kuklin summed up.