Cross-Channel Topology for Enhanced Drain Current in Organic Field-Effect Transistors

Organic field-effect transistors (OFETs) offer flexible platforms for chemical and biological sensing. However, they face a fundamental trade-off in conventional rectangular geometries where achieving high drain current requires shorter channel lengths, which reduces active sensing area and limits device sensitivity. To address this trade-off, we developed a cross-channel OFET topology consisting of four orthogonal branches intersecting at a central junction. Two device implementations were characterized: a cross-channel design with identical channel lengths across branches and a hybrid cross-channel (HCC) design with two distinct channel lengths alternating across the four branches. To systematically evaluate the geometric benefits of these designs, we fabricated conventional rectangular reference devices: rectangular single-branch reference matching one branch dimension and rectangular area References with the same footprint as the cross-channel devices. All devices were fabricated for two channel lengths of 50 and$100~\boldsymbol {\mu }$m. Electrical characterization of cross-channel topology designs was performed in multiple biasing modes of principal, parallel, diagonal, and single-branch configurations across both channel lengths. For the cross-channel design at$50~\boldsymbol {\mu }$m, the principal-mode configuration achieved a mean drain current of$- 26.1~\boldsymbol {\mu }$A, corresponding to 308% of the single-branch reference and 146% of the rectangular area reference. At$100~\boldsymbol {\mu }$m, the cross-channel configuration delivered$- 10.6~\boldsymbol {\mu }$A, representing 270% of the single-branch reference and 130% of the rectangular area reference. The HCC design demonstrated tunable current responses across biasing modes, with the principal configuration reaching$- 19.2~\boldsymbol {\mu }$A. These results establish that cross-channel topologies offer a scalable, fabrication-compatible approach to simultaneously achieving high drain current and expanded sensing area in field-effect transistor-based platforms without requiring modifications to semiconductor materials or processing conditions.