Optical and structural properties of ternary nanoaggregates in CsI-PbI₂co-evaporated thin films

Abstract

Thin films were grown by vacuum co-evaporation of CsI and PbI 2 compounds from two independent crucibles. X-ray diffraction spectroscopy revealed formation of CsPbI 3 and Cs 4 PbI 6 nanoaggregates in the thin film samples and gave an estimate of their volume percentage as well. It provided also the grain size estimates, which were compared with direct observation of a thin film surface by atomic force microscopy. The absorption, luminescence and decay kinetics characteristics of thin films grown were measured. The optical characteristics of the mentioned ternary nanoaggregates were determined and compared with those of CsPbX 3 and Cs 4 PbX 6 (X = Cl, Br) bulk structures.

Luminescent CsPbI3 and Cs4PbI6 Aggregates in Annealed CsI:Pb Crystals

“…The emission spectrum obtained under the 362 nm excitation is shown in Fig. 1d (dashed line).The position of the 435 nm emission band as well as the positions and relative intensities of its excitation bands are similar to those observed in [13] for a Cs 4 PbI 6 single crystal and in [15][16][17] for the Cs 4 PbI 6 aggregates in CsI-PbI 2 thin films. The intensity of the 435 nm emission is constant up to about 20 K, then it decreases and at T > 80 K this emission is practically quenched (Fig.…”

“…According to [8,16,17], the luminescence of a CsPbI 3 single crystal, unlike CsPbCl 3 and CsPbBr 3 crystals, arises from the radiative decay of the self-trapped excitons. The reason for this probably lies in the low (rhombic) symmetry of the CsPbI 3 lattice which might be favorable for exciton self-trapping [17].…”

“…In [13], the X-ray luminescence spectra have been studied at 77 K for the CsPbI 3 and Cs 4 PbI 6 -like aggregates dispersed in a CsI crystal lattice. In [15][16][17], the photoluminescence of these aggregates has been detected also in CsI-PbI 2 thin films grown by vacuum co-evaporation of CsI and PbI 2 powders on quartz or glass substrates. In the present paper, the characteristics of various aggregates thermally created in CsI : Pb crystals and dispersed in a CsI single crystal lattice have been studied in more detail in the 4.2-300 K temperature range.…”

Luminescent Kinetic Characteristics of Cspbcl_3 Aggregates Dispersed in Rb_{1-X}cs_{x}cl (X=0.05-0.2) Matrices

“…Lead-containing nanocrystals formed in the matrices having the CsCl crystal structure were directly observed only in the studies of the surface of thin films CsX:PbX 2 (X = Cl, Br, I) using the atomic force microscopy (AFM) method [6][7][8].…”

“…Using the AFM method we directly observe the lead-containing nanocrystals dispersed in the matrices of the Rb 1−x Cs x Cl (x = 0.05 ÷ 0.2) solid solutions. In these studies the crystals with cleaved surfaces are used, which makes them more advantageous compared to the thin film studies [6][7][8] where observation of nanocrystals is distorted by the thin film structure.…”