Frequency domain identification of NPB transporting properties of organic semiconductor based on particle swarm optimization algorithm

In order to study the carrier transporting properties in organic semiconductors (OSC), a single device with structure ITO/NPB/Ag is made, and the corresponding admittance model in theory is built.A group of impedance samples under different DC bias voltages of the device are obtained by small sinusoidal signal frequency test method. The fitness function of model parameters identification problem which considers both the real and imaginary parts of OSC impedance is defined. The particle swarm optimization (PSO) algorithm is used to identify dispersion coefficient M, α and hole mobility time τ_dc. The experiment results show that values of impedance´s real and imaginary parts fitted from parameters which are identified by PSO are very close to practical measured values, and the hole mobility time τ_dc satisfies exponent relation with DC bias voltage.