Observation of the Mott–Gurney law in tris (8-hydroxyquinoline) aluminum films

Abstract

We show that tris (8-hydroxyquinoline) aluminum (Alq3) thin films produced and characterized under ultrahigh vacuum conditions present a well-defined squared-law dependence of the injected current on the applied voltage at applied electric fields of the order of 0.25–1 MV/cm. From this, one derives an electric-field-independent electron mobility of the order of 10−7 cm2/(V s), with a variation between different samples of about one order of magnitude. Observations of current–voltage characteristics with clear indications of trap-filling and space-charge-limited conduction at high fields in Alq3 excludes the existence of traps with an exponential distribution of trap energies, as is commonly assumed in amorphous materials.

Effects of source and substrate temperatures on the properties of ITO/CuPc/C60 heterostructure prepared by physical vapor deposition

“…By least-square fitting, for low biases (V=0-0.4 V) as listed in Table 1, a L ¼ 1.270.1 indicates that the transport behavior is in a mixed regime governed by ohmic law (a ¼ 1) and Child-Langmuir law (a ¼ 1.5). However, as the electric field increases, a transition was observed from an ohmic law to a Mott-Gurney law, and during the transition a large value of a ¼ 8 was obtained, which may be caused by the onset of carrier injection and trap filling [24]. Based on this finding, the scattered values of a H for high biases (V ¼ 0.5-1.0 V) ranging from 2.1 to 4.7 (as listed in Table 1) indicate that the electric fields applied to these samples are near the onset of the above-mentioned transition.…”

“…4 shows the dark and illuminated J-V characteristics of two typical ITO/CuPc/C 60 /Ag devices fabricated at T sub ¼ 30 and 90 1C, respectively. For dark J-V curves, in view of the very thin layer thickness of the samples, a space charge limited current (SCLC) can dominate the transport behaviors [23,24]. Thus, J-V behavior follows a simple power law as JpV a , where a=1.5 for the case of negligible energy loss of the carriers and known as Child-Langmuir law, and a=2.0 for the case of constant mobility and known as Mott-Gurney law.…”

Naphthalimide-derivative with blue electroluminescence for OLED applications

“…The mobility in the NPOX is found to be independent of the applied field. This independence of the mobility on the electric field was also observed in Tris(8-hydroxyquiniline)Al, Alq 3 , when the samples were prepared under ultrahigh vacuum conditions, as described by Kiy et al [25]. Therefore, in Alq 3 , deviations from J ∼ V 2 were attributed to the presence of impurities.…”

Studies of Transport Properties of Single Layer Devices Based on the Polyazomethine Thin Films

“…Relatively large carrier density and symmetric I-V characteristics for the Au-PPI-Au structure differs significantly in the current density magnitude from Au-PPI-Al asymmetric I-V characteristics. The former structure is suggested to reveal the space charge limited character with current voltage characteristic consistent with the Mott-Gurney law [10][11][12][13]:…”