Luminescence of ternary nanoaggregates in CsI–PbI 2 thin films

Abstract

Thin films of about 400 nm thickness were grown by vacuum co-evaporation of powders of CsI and PbI 2 compounds from two independent molybdenum crucibles on quartz and glass substrates. The absorption, luminescence and decay kinetics characteristics of thin films were measured in the temperature range 4–300 K. At 4.2 K the CsPbI 3 aggregates show an emission peak around 535 nm and a smooth excitation spectrum with sharp excitonic peak around 406 nm. The Cs 4PbI 6 aggregates emission is centered around 430 nm with two characteristic excitation peaks around 365 and 290 nm. The Cs 4PbI 6 phase shows well-expressed two-component decay kinetics similar to that of Cs 4PbX 6 (X=Cl,Br) and KI : Pb bulk materials. X-ray diffraction spectroscopy confirmed the formation of CsPbI 3 and Cs 4PbCl 6 nanoaggregates in the thin film samples.