The crystallization is done as follows: a special solution of halide salts, polyethylene glycol, and other precursors is mixed in a specific way at a given temperature. Then, the solution is applied to polyester fiber (in this case, a white one). After that, the sample is heated so as to eliminate the solvent. As soon as the solvent evaporates, the crystals start to grow rapidly; this process ends in 2-3 hours and can be sped up if the textile is put in vacuum.

The image was made under UV lighting of a mercury lamp. The physical effect that lies at the basis here is photoluminescence. The textile absorbs UV light and re-emits it in the visual band. The images were made with the help of a microscope with a 10x magnification.

Textile with perovskite crystals. Photo courtesy of Dmitriy Gets
Textile with perovskite crystals. Photo courtesy of Dmitriy Gets

The work of ITMO’s Laboratory of Hybrid Nanophotonics and Optoelectronics (PeroLab) is conducted as part of the Russian Science Foundation grant (№19-73-30023) focusing on perovskite-based flexible optoelectronic devices: solar cells, light-emitting diodes, and multipurpose devices. The researchers believe that in the future, they will succeed in creating fabric-embedded diodes, and the  samples above are a small step towards this goal.