Optical and Electrical Properties of Vacuum Evaporated Sexithiophene Thin Films

Abstract

Optical and Electrical Properties of Vacuum Evaporated Sexithiophene Thin Films have been studied in the present work. The optical properties of Sexithiophene layers have been studied by absorption spectroscopy and fluorescence. From the optical studies, it has been observed that sexithiophene can be absorbed in the visible region and the electronic transitions have been occurred in the absorption spectra and fluorescence spectra. The weak fluorescence of 6T thin film would be an asset to the photovoltaic conversion of solar energy. The total conversion efficiency of the fabricated cells has been calculated as η = 0.7 10-2%. It is found that this very poor yield has been obtained mainly due to two factors. The first concerns the rate of photogeneration of free charges in the organic semiconductor since the excitons formed by light absorption of strong Frenkel excitons. The second is due to the small overlap of the absorption spectrum with the emission spectrum of the lamp. This manifest in the low lifetime of free carriers 4 3 μs   from compared to the transit time 187 μs which weakened due to the low carrier mobility.