Charge Transport Study of 2,2',7,7'-Tetrakis(N,N-di-4-methoxyphenyl amino)-9,9'-spirobifluorene Using Impedance Spectroscopy

概要

論文の詳細を見る
The conduction mechanism in 2,2',7,7'-tetrakis(N,N-di-4-methoxyphenyl amino)-9,9'-spirobifluoren (spiro-MeOTAD) has been studied by impedance spectroscopy (IS) by using indium tin oxide (ITO)/spiro-MeOTAD/gold (Au) hole only device. The device could be modelled by an equivalent parallel RC network with a low contact resistance R_{\text{s}} in series, in which the bulk geometrical capacitance above resonance frequency of spiro-MeOTAD remains unchanged while the bulk resistance R_{\text{p}} changes with bias voltage. Upon increasing the bias voltage the conductivity of deposited film has increased by one order of magnitude (i.e., from {\sim}10^{-9} to {\sim}10^{-8} \Omega^{-1} cm-1) whereas the dielectric relaxation time (\tau) decreased from 1.7 \times 10^{-4} to 1.2 \times 10^{-5} s. Capacitance spectra of hole-only spiro-MeOTAD devices indicate the validity of the Space charge limited current (SCLC) model with localised states distributed in energy and field-dependent mobility.
2011-06-25