DETERMINATION OF ANISOTROPIC ELECTRON-TRANSPORT PROPERTIES OF 2 LANGMUIR-BLODGETT ORGANIC MULTIPLE-QUANTUM WELLS

The first experimental determination of the anisotropy of the electron transfer rate in two Langmuir-Blodgett insulator multilayer systems i s presented. A key feature of these two multilayer systems is the pres ence of the planar-conjugated phthalocyanine ring. The first system is composed of tetra-tertiary-butyl phthalocyanine monosulphonic acid. I n it the ring planes are approximately normal to the layer plane. The second system is composed of the two-ring phthalocyanine, HOSiPcOSiPcO Si(n-C6H13)3. In it the rings lie in the layer plane.The anisotropy of the systems is determined from a model of the recombination rate, at high density, of photoelectrons and photoholes on the same layer. The ratio of the intralayer to interlayer transfer rate between adjacent r ings is found to be 1500 and 570 respectively. Coupled with a previous determination of the interlayer transfer time of 1.6 and 0.15 ns, the intralayer transfer times are then determined as 1.07 and 0.28 ps res pectively. The in-plane mobilities can then be determined as 0.34 and 2.4 cm2 s-1 V-1 respectively. The results justify regarding these syst ems as organic multiple quantum wells.