The polyiodides can be made by addition of stoichiometric amounts of I2 to solutions containing I− and I−3, with the presence of large countercations to stabilize them.
For example, KI3·H2O can be crystallized from a saturated solution of KI when a stoichiometric amount of I2 is added and cooled.
[15][16] Polyiodide has been used to improve the scalability in the synthesis of halide perovskite photovoltaic materials.
[17] Solid state compounds containing linear-chain polyiodide ions exhibit enhanced conductivity[18][19] than their simple iodide counterparts.
The conductivity can be drastically modified by external pressure, which changes the interatomic distances between iodine moieties and the charge distribution.