Title : A comparative analysis of structural, optical, excitonic and electronic properties of new long chain alkyl bismuth Iodide perovskite materials.
Abstract:
Lead-free metal halide perovskites prove to be outstanding materials for light harvesting due to their excellent optoelectronic properties and lower-temperature processability. The search for lead-free perovskites is expensive, and several metal cations are under investigation; among these, bismuth is one of them. In this work we synthesized new Bi based perovskite films, butylammonium bismuth iodide (BBI) and octyle ammonium bismuth iodide (OBI), by one step spin coating method and compared them with methyl ammonium bismuth iodide (MBI) films. The perovskite films were subjected to a range of characterization techniques to examine and analyze the morphological, optical, electrical and structural properties of the films. All the films demonstrated excellent substrate coverage and stability. X-Ray Diffraction analysis (XRD) showed that all the perovskite structures were crystalline in nature. The morphology of the films were studied using Scanning Electron Microscopy (SEM). UV-vis and Photoluminescence Spectroscopy (PL) confirmed that all the synthesized films exhibit a strong light absorption in visible region and featuring an optical band gap of 1.9ev for MBI, 2.07ev for BBI and 2.2ev for OBI. Furthermore, we conducted low-temperature micro photoluminescence (PL) measurements on alkyl ammonium bismuth iodide perovskites. Our results demonstrated a pronounced shift towards longer wavelength PL intensity of spectrum. These results pave the way for the development of new highly stable Pb-free perovskite materials with single step deposition method for optoelectronic devices.
