Pyronin y as new organic semiconductors: Structure, optical spectroscopy and electrical/dielectric properties

Abstract

Pyronin Y (PY) is an organic dye which is used extensively before in staining RNA and other organo-cells. Nowadays, it can be used in electronic and optoelectronic devices as an organic semiconductor. X-ray diffraction (XRD) showed that PY is a polycrystalline material and both the lattice structure and the lattice constants were calculated for the first time by using crysfire and checkcell software. In addition, Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and differential thermal analysis (DTA) have been studied. Diffused reflectance (DR) of pyronin Y in the wavelength 200-2300 nm was measured and analyzed to calculate the optical parameters and the absorption region of pyronin Y. The optical band gap was calculated on the basis of Kubelka-Munk theory (KMT). It is clear that there are three optical band gaps in the studied range of photon energy and equal 2.13, 1.82 and 1.67 eV. The high band gap (2.13 eV) is corresponding to the fundamental band gap (between HOMO and LUMO) and other two gaps (1.82 and 1.67 eV) are corresponding to the trap energy inside the band gap (i.e. onset gaps). On the basis of the DR measurements and applicable of KMT, we are able to calculate the refractive index, absorption index and the dielectric constants for pyronin Y in powder form. Pyronin Y is an organic semiconductor due to the increasing of DC (direct current) electrical conductivity with increasing temperature and the electronic parameters of direct current was calculated. Ac electrical conductivity, dielectric constant and dielectric loss were calculated and interpreted on the basis of ac fields causes the different kind of polarization inside the materials. Hence, pyronin Y can be used as a new materials for advanced technology.