Characterization of temperature-dependent carrier transport in disordered indium-tin-oxide/poly(3,4-ethylenedioxythiophene): Poly(styrenesulfonate)/ polyfluorene/Ca/Al polymer structures

The temperature-dependent electrical characteristics of polyfluorene-based polymer structures over a temperature range from 200 to 300 K are systematically investigated in this study. Initially, using the definitions of the Berthelot-type model, it is found that the sample exhibits a higher Berthelot-type temperature T_B with high driving voltage, indicating that carrier transport in a disordered system manifests Berthelot-type behaviors. The ideal current density-voltage curve for the polymer structures given the carrier transmit mechanism is further elucidated by taking into account the ohmic conduction, trap charge limited current, and Mott and Gurney model of space charge limited current. The proposed procedure is simple and can be used to characterize the material with reasonable accuracy. We also study the density of the traps H_t, and the characteristic energy of the distribution E_t to better understand the carrier-transport process in organic materials and structures.