Low Contact Resistance Organic Single-Crystal Transistors with Band-Like Transport Based on 2,6-Bis-Phenylethynyl-Anthracene.

ABSTRACT

Contact resistance has become one of the main bottlenecks that hinder further improvement of mobility and integration density of organic field-effect transistors (OFETs). Much progress has been made in reducing contact resistance by modifying the electrode/semiconductor interface and decreasing the crystal thickness, however, the development of new organic semiconductor materials with low contact resistance still faces many challenges. Here, 2,6-bis-phenylethynyl-anthracene (BPEA) is found, which is a material that combines high mobility with low contact resistance. Single-crystal BEPA OFETs with a thickness of ≈20 nm demonstrated high mobility of 4.52 cm2 V-1 s-1, contact resistance as low as 335 Ω cm, and band-like charge transport behavior. The calculated compatibility of the EHOMO of BPEA with the work function of the Au electrode, and the decreased |EHOMO-ΦAu| with the increase of external electric field intensity from source to gate both contributed to the efficient charge injection and small contact resistance. More intriguingly, p-type BPEA as a buffer layer can effectively reduce the contact resistance, improve the mobility, and meanwhile inhibit the double-slope electrical behavior of p-channel 2,6-diphenyl anthracene (DPA) single-crystal OFETs.