Regensburg 2010 – scientific programme

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DS: Fachverband Dünne Schichten

DS 15: [HL] Organic Semiconductors: Transistors and OLEDs (Joint Session DS/CPP/HL/O)

DS 15.8: Talk

Tuesday, March 23, 2010, 11:30–11:45, H15

Carrier density in a Gaussian density of states: Approximation for the Gauss- Fermi integral — •Gernot Paasch¹ and Susanne Scheinert² — ¹IFW Dresden — ²TU Ilmenau

The density of hopping transport states in organics can be approximated by a Gaussian DOS. As a consequence, the mobility becomes a function of carrier density, field and of course temperature. Such dependencies can now be implemented easily in advanced device simulation programs as Sentaurus Device. However, the carrier density as function of the Fermi energy is not taken into account until now. For inorganic semiconductors with a square root DOS the situation was similar with the carrier density expressed by the Fermi- Dirac integral F1/2. Further Fermi-Dirac integrals are needed for the electronic energy density and for Einstein’s relation. For these cases analytical approximations have been developed early allowing for fast simulation. For the Gaussian DOS the carrier density is given by the integral over the product of Gaussian DOS and Fermi-Dirac distribution, the Gauss- Fermi integral. Related integrals describe the electronic energy density and occur in Einstein’s relation. Here we present an extremely simple and accurate approximation for the Gauss-Fermi integral and discuss its potential applicability in simulation of organic devices.