Gamma radiation induced variation in structure formation and optical characteristics of evaporated tris [2-phenylpyridinato-C<sub>2</sub>,N]iridium(III) films prepared by electron beam evaporator in photovoltaic applications
E. Elesh, D.G. El-Damhogi, Zainab Majeed Mohamed
Abstract
Abstract This study fabricates novel tris (2-phenylpyridinato-C 2 , N] iridium III <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi>I</mml:mi> <mml:mi>r</mml:mi> <mml:msub> <mml:mrow> <mml:mo stretchy="false">(</mml:mo> <mml:mi>p</mml:mi> <mml:mi>p</mml:mi> <mml:mi>y</mml:mi> <mml:mo stretchy="false">)</mml:mo> </mml:mrow> <mml:mrow> <mml:mn>3</mml:mn> </mml:mrow> </mml:msub> </mml:math> thin films using an electron beam evaporator and investigates their structure formation, surface morphology, and linear/nonlinear optical properties. The structural features of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi>I</mml:mi> <mml:mi>r</mml:mi> <mml:msub> <mml:mrow> <mml:mo stretchy="false">(</mml:mo> <mml:mi>p</mml:mi> <mml:mi>p</mml:mi> <mml:mi>y</mml:mi> <mml:mo stretchy="false">)</mml:mo> </mml:mrow> <mml:mrow> <mml:mn>3</mml:mn> </mml:mrow> </mml:msub> </mml:math> thin films were examined using Fourier Transform spectroscopy (FTIR), x-ray diffraction (XRD), Scanning Electron Microscope (SEM). The optical c.characteristics for various doses of gamma radiation (3 kGy, 6 kGy and 9kGy) were investigated using a UV-Vis-NIR spectrophotometer in the wavelength range from 200 nm to 2500 nm. In addition, the values of fundamental energy gap (E fundamental ) values showed a reduction from 2.30 to 1.92 eV and urbach energy <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mo stretchy="false">(</mml:mo> <mml:msub> <mml:mrow> <mml:mi>E</mml:mi> </mml:mrow> <mml:mrow> <mml:mtable columnalign="left"> <mml:mtr> <mml:mtd> <mml:mi>U</mml:mi> </mml:mtd> </mml:mtr> </mml:mtable> </mml:mrow> </mml:msub> <mml:mo stretchy="false">)</mml:mo> </mml:math> increasing from 0.23 to 0.30 when the deposited film irradiated for 9 kGy. The third-order nonlinear susceptibility ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msup> <mml:mrow> <mml:mi>χ</mml:mi> </mml:mrow> <mml:mrow> <mml:mo stretchy="false">(</mml:mo> <mml:mn>3</mml:mn> <mml:mo stretchy="false">)</mml:mo> </mml:mrow> </mml:msup> </mml:math> ), the nonlinear absorption coefficient ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi>β</mml:mi> </mml:math> ) and the nonlinear refractive index ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mrow> <mml:mi>n</mml:mi> </mml:mrow> <mml:mrow> <mml:mn>2</mml:mn> </mml:mrow> </mml:msub> </mml:math> ) were determined for all gamma doses. Furthermore, The optical electronegativity ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mrow> <mml:mi>η</mml:mi> </mml:mrow> <mml:mrow> <mml:mi>o</mml:mi> <mml:mi>p</mml:mi> <mml:mi>t</mml:mi> </mml:mrow> </mml:msub> </mml:math> ), the first moment ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mrow> <mml:mi>M</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>1</mml:mn> </mml:mrow> </mml:msub> </mml:math> ), the second moments of optical spectra ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mrow> <mml:mi>M</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>3</mml:mn> </mml:mrow> </mml:msub> </mml:math> ), the oscillator strength ( f), the dispersion energy ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mrow> <mml:mi>E</mml:mi> </mml:mrow> <mml:mrow> <mml:mi>d</mml:mi> </mml:mrow> </mml:msub> </mml:math> ), infinite dielectric constant ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mrow> <mml:mi>ε</mml:mi> </mml:mrow> <mml:mrow> <mml:mi>∞</mml:mi> </mml:mrow> </mml:msub> </mml:math> ), oscillator energy,oscillator energy ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mrow> <mml:mi>E</mml:mi> </mml:mrow> <mml:mrow> <mml:mn>0</mml:mn> </mml:mrow> </mml:msub> </mml:math> ), the lattice dielectric constant ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mrow> <mml:mi>ε</mml:mi> </mml:mrow> <mml:mrow> <mml:mi>L</mml:mi> </mml:mrow> </mml:msub>