Current transport across the pentacene/CVD-grown graphene interface for diode applications

Area of Science:

• Materials Science
• Organic Electronics
• Surface Science

Background:

• Pentacene and graphene are key materials in organic electronics.
• Understanding charge transport at organic semiconductor/graphene interfaces is crucial for device performance.

Purpose of the Study:

• To investigate and compare electronic transport properties at the pentacene/graphene interface with pentacene/HOPG and pentacene/Cu interfaces.
• To elucidate the dominant charge transport mechanisms (Poole–Frenkel and thermionic emission) at these interfaces under varying voltage conditions.
• To assess the suitability of graphene as a contact material for pentacene-based devices.

Main Methods:

• Fabrication of diodes utilizing pentacene layered on graphene, highly oriented pyrolytic graphite (HOPG), and copper (Cu) substrates.
• Electrical characterization of the fabricated diodes to measure current-voltage (I-V) characteristics.
• Analysis of transport mechanisms, including Poole–Frenkel emission and thermionic emission, by fitting experimental data to theoretical models.

Main Results:

• Electronic transport across the pentacene/graphene interface differs significantly from pentacene/HOPG and pentacene/Cu interfaces.
• At low voltages, pentacene/graphene diodes exhibit Poole–Frenkel emission, while pentacene/HOPG and pentacene/Cu diodes show thermionic emission.
• At high voltages, Poole–Frenkel emission dominates conduction for all investigated interfaces.
• A combined model of thermionic and Poole–Frenkel emission accurately describes the observed current transport.

Conclusions:

• Graphene serves as a low-resistance contact for pentacene, particularly beneficial when flat-lying pentacene orientation and transparent electrodes are required.
• The findings enhance the understanding of charge transport physics at organic semiconductor/graphene interfaces.
• Graphene presents a promising alternative to traditional metal electrodes for advanced organic electronic applications.