Quasi-static modeling of an organic Schottky diode with trapped charge

The fundamental aspects of trap analysis in charge transport of organic semiconductors are reviewed by focusing on the role of traps in I-V characteristics of an organic Schottky diode. A p-type organic semiconductor based device is considered and the trap distribution is assumed to vary exponentially with energy. A numerical model is developed to determine the trapped charge concentration in the bulk region of organic semiconductor during the steady state trap free space charge limited current conduction. This model was used to deduce an analytical expression that relates the charge ratio ¿ with the Fermi level energy E_F. This expression was utilized to determine the value of Fermi level energy E_F corresponding to the charge ratio taken from the previously reported work based on an organic Schottky diode. Finally, the estimated value of Fermi level energy is applied to calculate the number of trapped charges through MATLAB based simulations. The concentration of trapped charges was found to be 1.54 × 10¹⁶ cm^-3 which is in good agreement with the reported experimental results.