Thin Solid Films, Vol.333, No.1-2, 176-184, 1998
Electrical, optical and photovoltaic effect in pyronine G (Y) based thin film sandwich devices
The optical, electrical and photovoltaic properties of pyronine G (Y) have been investigated in the form of thin film devices. The molecular system of the pyronine shows the phenomenon of extended conjugation which is in fact responsible for its absorption in the longer wavelength, i.e. 540 nm of the visible spectrum. Pyronine G (Y) was employed in the form of thin film for the fabrication of sandwich devices having ITO/pyronine/Al and ITO/pyronine/In structures. The present communication deals with the study of optical, electrical and photoelectrical properties of ITO/PYR/Al and ITO/PYR/In devices by measuring the J-V characteristics in dark as well as under illumination and C-V characteristics in dark. The photoaction spectra of the devices and absorption spectra of PRY thin films were also employed for evaluating the photogeneration process in the device. The observations reveal the formation of a Schottky barrier at AI-PYR and In-PYR interfaces and ohmic contact at the ITO-PYR interface, showing a diode ideality factor greater than unity. From the detail analysis of J-V characteristics of the device at different temperatures, it is found that the position of the Fermi level lies above the valence band indicating the semiconductivity of PYR as p-type. The photogeneration mechanism of charge carriers in the device involves the dissociation of excitons at AI-PYR and In-PYR interfaces in their respective devices. Various electrical and photovoltaic parameters were also calculated from the analysis of experimental results and discussed in detail. The mechanism of the photoconductivity process in the PYR thin film is been discussed in detail.