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Charge carrier transport phenomena in some organic heterojunctions

O-L. RASOGA1,* , M. SOCOL1, F. STANCULESCU2

Affiliation

  1. National Institute of Materials Physics, 105 bis Atomistilor Street, P.O. Box MG-7, Bucharest-Magurele, 077125, Romania
  2. University of Bucharest, Faculty of Physics, 405 Atomistilor Street, P.O. Box MG-11, Bucharest-Magurele 077125 Romania

Abstract

This paper presents investigations on the electrical transport phenomena in sandwich type inorganic/single (double) organic layer/inorganic such as silicon; ITO/TPyP, Alq3, α-NPD; ZnPc; perylene; PTCDA/silicon and inorganic (metal)/organic/metal such as silicon (Al)/ZnPc; α-NPD; TPyP/copper, Al, structures, prepared by vacuum evaporation. For most of these heterostructures the I-V characteristics in the static regime have a near ohmic behaviour only at low voltages (<1 V) that changes in a power dependence with a coefficient n=2 or n=3 at higher voltages because of the space charge or trapped charge phenomena. For the same applied voltage, the n type Si electrode injects more charge carriers in TpyP than in Alq3. For higher voltages (>10V) an increased number of charge carriers are injected from n type Si in Alq3 compared to TpyP. The injection properties of the interface ITO, Cu, Al electrode/organic layer have also been investigated. The best injection has been obtained through ITO/ZnPc interface. For a grid configuration of the Al electrodes the transport phenomena are determined by the resistivity of the structure..

Keywords

Organic semiconductor, Electrical properties, Heterostructures.

Submitted at: Dec. 15, 2008
Accepted at: April 28, 2009

Citation

O-L. RASOGA, M. SOCOL, F. STANCULESCU, Charge carrier transport phenomena in some organic heterojunctions, Journal of Optoelectronics and Advanced Materials Vol. 11, Iss. 4, pp. 509-514 (2009)