Frequency Dependent Electrical and Dielectric Properties of Au/P3HT:PCBM:F4-TCNQ/n-Si Schottky Barrier Diode

In this study, poly(3-hexylthiophene):[6,6]-phenyl-C61-butyric acid methyl ester: 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (P3HT:PCBM:F4-TCNQ) organic film was deposited on n-type silicon (n-Si) substrate by spin coating method. The electrical and dielectric analysis of Au/P3HT:PCBM:F4-TCNQ/n-Si Schottky barrier diode was conducted by means of capacitance-voltage (C-V) and conductance-voltage (G/omega-V) measurements in the frequency range of 10 kHz-2 MHz. The C-V-f plots exhibit fairly large frequency dispersion due to excess capacitance caused by the presence of interface states (N (ss)). The values of N (ss) located in semiconductor bandgap at the organic film/semiconductor interface were calculated by Hill-Coleman method. Experimental results show that dielectric constant (epsilon') and dielectric loss (epsilon aEuro(3)) decrease with increasing frequency, whereas loss tangent (tan delta) remains nearly the same. The decrease in epsilon' and epsilon aEuro(3) was interpreted by the theory of dielectric relaxation due to interfacial polarization. It is also observed that ac electrical conductivity (sigma (ac)) and electric modulus (M' and MaEuro(3)) increase with increasing frequency.