Comparative Study of Silver and Gold Source/Drain Contacts for Organic Thin‐Film Transistors with Low Contact Resistance

Abstract

Abstract Flexible low‐voltage organic thin‐film transistors (TFTs) with Ag source/drain contacts are fabricated, and the contact resistance is measured using the transfer length method. The TFTs are fabricated in the inverted coplanar (bottom‐gate, bottom‐contact) device architecture, using the vacuum‐deposited small‐molecule semiconductor dinaphtho[2,3′b:2′,3′‐f]thieno[3,2‐b]thiophene (DNTT). Prior to the semiconductor deposition, the contact surface is functionalized with a chemisorbed monolayer of pentafluorobenzenethiol (PFBT). For comparison, TFTs with PFBT‐functionalized Au source/drain contacts are fabricated on the same substrate. Overall, the performance of the TFTs with the Ag contacts is very similar to that of the TFTs with the Au contacts, and the contact resistance of the TFTs with the Ag contacts (377 Ωcm) is the smallest reported to date for p‐channel organic TFTs with a contact material other than Au or Pt.