Electrical and optical properties of an organic semiconductor metal-free phthalocyanine (C₃₂H₁₈N₈)

¹ Physics Department, Tarbiat Moallem University, 49 Mofateh avenue, Tehran, Iran
² Physics Department, University of Sabzevar Tarbiat Moallem, Sabzevar, Iran

^a e-mail: azim@saba.tmu.ac.ir

Received: 16 February 2012
Revised: 21 April 2012
Accepted: 9 May 2012
Published online: 5 July 2012

Abstract

In a recent work we calculated some electronic properties of metal-free phthalocyanine such as band structure, density of states and energy gap. We have also presented some optical properties such as dielectric function, electrical loss function, optical conduction, absorption and refractive index, some of which have never been studied before. Calculations were performed in the framework of density functional theory (DFT), using the full-potential linearized augmented plane wave (FP-LAPW) method. This study presents the electrical gap energy of metal-free phthalocyanine to be E_g = 2.4 eV which is in good agreement with experimental data. A trap energy level is also observed. Optical band gap is about 2.48 eV with an optical trap level at 1.48 eV. In addition, we obtained the static refractive index in the x-, y- and z-directions as n_0xx = 2.43, n_0yy = 2.06 and n_0zz = 2.32. Finally, absorption spectra display the existence of strong absorption bands at the wavelengths of 400 and 800 nm which compare favorably with experimental results.