The absorption spectra of thin films of ternary compounds in the RbI-PbI2 system

Formation of compounds RbPbI3 and Rb4PbI6 in the RbI-PbI2 system is revealed, and their absorption spectra are investigated in an energy interval of 2-6 eV and at temperatures from 90 to 500 K. It is established that the low-frequency exciton excitations are localized in PbI64-structural elements of the crystal lattice, they are classified as excitons of intermediate coupling and are of a three-dimensional character in RbPbI3 and a quasi-two-dimensional one in Rb4PbI6. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4758777]