Effect of Thermal Annealing on the Optical and Morphological Properties of (AETH)PbX4 (X = Br, I) Perovskite Films Prepared Using Single Source Thermal Ablation

Films of the new organic−inorganic hybrid materials AETHPbX4 (AETH = 1,6-bis[5‘-(2‘ ‘-aminoethyl)-2‘-thienyl]hexane; X = Br, I) were fabricated using single source thermal ablation (SSTA). The as-deposited films were optically smooth and nominally amorphous. The progressive effects of annealing on the structural, optical, and morphological properties of the films were monitored using powder X-ray diffraction, optical spectroscopy, and atomic force microscopy (AFM). Short duration postdeposition annealing at mild temperatures resulted in well-crystallized films of the AETHPbX4 hybrid perovskites. It was found that up to some critical annealing temperature (∼120 °C), the emission wavelength and the exciton absorption of the compounds shifted to lower energies as the annealing temperature increased. As confirmed with AFM measurements, this shift in optical properties suggests a gradual increase of the grain size with annealing temperature. When the samples were annealed at higher temperatures (>180 °C) their...