Investigation of hole-injection in α-NPD using capacitance and impedance spectroscopy techniques with F4TCNQ as hole-injection layer: Initial studies

The charge accumulation leading to injection at the organic interface in the sequentially doped hole-only device structure is studied using capacitance and impedance based spectroscopic techniques. In this paper, we investigate the role of p-type dopant 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4TCNQ) in the charge transport properties of N,N′-Di(1-naphthyl)-N,N′-diphenyl-(1,1′-biphenyl)-4,4′-diamine (α-NPD) through sequential deposition. We show that the hole injection into α-NPD increases with the increase of interlayer (F4TCNQ) thickness by correlating the current density-voltage, capacitance-voltage, capacitance-frequency and impedance measurements.