A study of molecularly doped polymer-to-metal contacts by steady state injection current measurements

Abstract

Temperature dependent characteristics of the steady injection current from various metal contacts into molecularly doped polymers were studied. The dopants were DEH, BD, and TPTA. Au contacts produced space-charge-limited currents in all polymers, i.e. were ohmic. Contacts of Cu (in some cases) and of Sn, Al, and In were emission limited, and gave space-charge-free currents containing both Arrhenius and constant/ temperature terms. The Arrhenius components correlated with the metal workfunctions. The ionization energies deduced for DEH and BD, namely 5.34 and 5.15 eV, respectively, agreed well with the published spectroscopic values. An experimental value for the ionization potential of TPTA, namely 5.42 eV, is found here for the first time. The results suggest steady state measurements as a viable alternative to UV spectroscopy for determining the ionization energies of doped polymers.

Interface phenomena in double-layer organic photoreceptors

“…However, the situation in BD is different. Accepting the above value for E p and an ionization energy for BD of 5.14 eV (Sasvari and Juhasz 1997), the transport level in BD lies 0.09 eV above the valence band of the pigment, while δE BD is zero. For comparison, spectroscopic determination of the height of the transport level above the VB yields 0.11 eV (Kitamura and Chigono 1991).…”

“…The depth of the valence band below the vacuum level is called E p . The ionization energies of the transport levels in the doped polymers are E 0 , and were determined by Sasvari and Juhasz (1997)…”

“…Indeed, the injection efficiency must depend on the relative potential energies and populations of the states at the interface. In this paper we investigate the temperature and field dependence of the injection from a phthalocyanine PGL into various doped polymers and, drawing on results for the ionization energies (Sasvari and Juhasz 1997), we compare the measured efficiencies against simple models of the interface.…”

Trap Generation Dynamics in Photo-Oxidised DEH Doped Polymers

“…This incorrect interpretation arises through the substitution of the φG product in the exponent term of Equation 9 with the constant parameters from Equation (10). As the UV generation rate G is reduced, however, φ will increase but is restricted to a maximum value of unity.…”

“…Thin films of such MDPs are commonly used by the xerographic, laser printer and organic LED display industries [5]. An interesting class of MDPs that have received considerable attention in the scientific literature are those based upon hydrazone molecules and in particular p-diethylaminobenzaldehyde-1,1'-diphenylhydrazone (DEH) [6][7][8][9][10]. The DEH molecule also exhibits a unique photo-cyclic oxidation reaction which results in the production of an indazole molecule 1-phenyl-3-(4-diethylamino-1-phenyl)-1,3-indazole (IND) [11,12].…”