Investigation of charge transport in Vanadyl-phthalocyanine with molybdenum trioxide as a buffer layer: Impedance spectroscopic analysis

• A sandwich structure of Vanadyl-phthalocyanine based diodes D1 (with MoO3) and D2 (without MoO3) is fabricated by thermal evaporation method.
• Improvement in the current density through the device is investigated using current density – voltage (J–V) and capacitance – voltage (C–V) characteristics.
• The conduction mechanism is space charge limited with exponential trap distribution.
• The dominant mechanism in charge transport is by hopping through the available sites which is discussed based on ac conductivity measurements and by adopting Correlated barrier hopping (CBH) model.

Charge transport in organic materials is one of the intrinsic properties, which governs the device performance. In this paper, we report the fabrication and electrical characterization of two diodes ITO/VOPc/MoO3/Al and ITO/VOPc/Al. We investigate the electrical conduction of Vanadyl phthalocyanine (VOPc) in both the devices and also the effect of MoO3 as a buffer layer. Improvement of current density through the device is estimated using current density – voltage characteristics and capacitance – voltage characteristics. Space charge limited current (SCLC) conduction with an exponential trap distribution is observed from Impedance measurements. The dominant hopping charge transport is discussed based on ac conductivity measurements and by adopting Correlated barrier hopping (CBH) model.

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