ORGANIC PHOTOCONDUCTOR TTF-TCNQ (TETRATHIAFULVALENETETRACYANOQUINODIMETHANE): A POTENTIAL ROOM TEMPERATURE INFRARED DETECTOR AT 10 ?m H. R. Mohajeri Moghaddam* and N. Peyghambarian

Abstract

The absorption properties of charge transfer organic semiconductor TTF-TCNQ
(tetrathiafulvalene-tetracyanoquhodimete ) filmsdeposited on KBr singlecrystal,
quartz and glass substrates in far infrared have been investigated. An absorption edge
at ?10 ??m was observed. Photoconductivity, photoconduction efficiency and gain
and photocarrier's lifetime have been measured. The results show an electric field
dependent photoconductivity.At an applied voltage of 14 V the photoconductivity
reaches 1.2 (ohm-cm) which is almost the same as that of its DC dark
conductivity, i.e. 1.8 (ohm-cm) . Low temperature results show that the
performance of the detector does not improve, but the field dependency, which was
shown at room temperature, did not occur at low temperatures. The laser power
dependency of the photocarriers showed that a single photon absorption process is
involved. Slight deviation from linear dependency could be attributed to trapping in
the band gap. It was concluded that the material may potentially be used as a CO laser detector