Effect of intermediate phases on the optical properties of PbI-rich CHNHPbI organic-inorganic hybrid perovskite

• Published in: Physical chemistry chemical physics : PCCP 2019-02, Vol.21 (9), p.5253-5261
• Main Authors: Sanches, Alonso W. P, da Silva, Marco A. T, Cordeiro, Neusmar J. A, Urbano, Alexandre, Lourenço, Sidney A
• Format: Article
• ISSN: 1463-9076; 1463-9084
• DOI: 10.1039/c8cp06916f

Methylammonium lead halide perovskite (CH 3 NH 3 PbI 3 ) films, with high PbI 2 concentration, were grown by the two-step spin coating method. The influence of the precursor concentration and annealing time on the optical and structural properties of the perovskite films was analyzed by optical absorption, photoluminescence, X-ray diffraction and scanning electron microscopy. The results showed that, in addition to the CH 3 NH 3 PbI 3 and PbI 2 phases, intermediate phases, such as (MA) 2 (DMF) 2 Pb 3 I 8 , were formed in the films, depending on the time and temperature of annealing, which can tune the optical absorption in the visible spectra. This intermediate phase induced the formation of perovskite nanowires, identified by SEM images, and their growth may be associated with the presence of the DMF solvent remaining in the PbI 2 film. Intermediate phases in the methylammonium lead halide perovskite (CH 3 NH 3 PbI 3 ) films produced by the two-step spin coating method.