Effect of thickness on the electrical and optical properties of MEH-PPV:TiO<inf>2</inf> nanocomposite for organic solar cell application

Abstract

The performance and properties of organic/inorganic nanocomposited poly[2-methoxy 5-(2'-ethyl-hexyloxy)-1,4-phenylene vinylene] (MEH-PPV):TiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> thin film at different thickness was investigated. MEH-PPV:TiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> nanocomposite thin film has been prepared on indium tin oxide (ITO) substrate using spin-coating method with different deposition time from 1 to 10 times at room temperature. The effect of different thickness on the electrical and optical properties of MEH-PPV:TiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> was characterized by using solar simulator under AM 1.5, 100mW/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> white light illumination and UV-Vis-NIR spectrophotometer respectively. From the current-voltage (I-V) measurement the result shows for 3 times of deposition, at thickness 719.413 nm gives the highest photoconductivity value, 35.2336×10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> S.m <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> . While for photoconductivity of 5, 7 and 10 times of deposition, there is no significant improvement were obtained. The optical properties were found to be strongly dependent on the thickness of nanocomposite thin films. The absorption coefficient reveals an improvement as the number of thickness increases with strong absorption at wavelength of 500 nm in visible ranges and 310 nm in UV ranges respectively.