Hydrated bovine serum albumin as the gate dielectric material for organic field-effect transistors

• Hydrated bovine serum albumin (BSA) can be treated as a natural bio-polyelectrolyte.
• Pentacene OFETs with BSA dielectric exhibit a μFE,sat value of 4.7 cm2 V−1 s−1 in air.
• Electric double-layer capacitors (EDLCs) are formed in hydrated BSA.
• EDLCs can well explain the high drain current at low operation voltage.

Bovine serum albumin (BSA) is a natural protein with good hydration ability which contains acidic and basic amino acid residues of ca. 34% in total. In vacuum, pentacene organic field-effect transistors (OFETs) with BSA as the gate dielectric exhibits a field-effect mobility value (μFE,sat) of 0.3 cm2 V−1 s−1 in the saturation regime and a threshold voltage (VTH) of ca. −16 V. BSA is easy to be hydrated in air ambient. Electrical properties of BSA in vacuum and hydrated BSA in air ambient are characterized. Similar to polyelectrolyte, hydrated BSA may act the gate dielectric with the formation of electric double-layer capacitors (EDLCs) to improve the device performance. In a relative humidity of 47%, the μFE,sat value increases to 4.7 cm2 V−1 s−1 and the VTH reduces to −0.7 V. Generation of mobile ions in hydrated BSA and the formation of EDLCs are discussed.

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