Charge transport mechanism and photovoltaic behaviour of undoped and I2 doped tris (1,10 phenanthroline) iron (II) complex (TPFe) thin film devices

Abstract

Tris (1,10 phenanthroline) iron (II) or Fe (Phen)2+ 3, a metal-to-ligand charge transfer (MLCT) type complex (TPFe), was employed in the form of thin films, for the fabrication of Schottky diodes, Al/ TPFe/ITO, where ITO is indium tin oxide. The effect of iodine doping on the electrical behaviour has been emphasized. The diodes exhibit a rectification effect which improves on iodine doping. The diodes can be classified as MIS Schottky diodes with a graded dopant profile. The current-voltage (J-V ), and capacitance-voltage (C-V ) characteristics, the photoaction spectra of the devices and the absorption spectra of the complex, reveal that both doped and undoped complexes behave as a p-type organic semiconductor which form a Schottky barrier with Al and an ohmic contact with ITO. Various electrical and photovoltaic parameters were determined from the detailed analysis of J-V and C-V characteristics and these are discussed in detail. The effect of I_2 doping on the rectification and photovoltaic properties is also discussed.