Anisotropic charge transport and contact resistance of 6,13-bis(triisopropylsilylethynyl) pentacene field-effect transistors fabricated by a modified flow-coating method

Abstract

Using a modified flow-coating method, bottom-gate/bottom-contact type organic field-effect transistors (OFETs) with a highly oriented active layer of 6,13-bis(triisopropylsilylethynyl) pentacene (TIPS-pentacene) were fabricated. The flow-coated TIPS-pentacene films were fairly uniform and consisted of arrays of needle-shaped crystals along the flow-coating direction. The uniformity allowed us to determine the contact resistance by a transfer line method. The usefulness of the modified flow-coating method for fabricating high performance OFETs has been demonstrated, and we found that not only the field-effect mobility but also the contact resistance significantly depends on the channel current direction with respect to the flow-coating direction.

Contact engineering in organic field-effect transistors

“…Most OSCs have isotropic charge transport, and the transport mobility perpendicular to the channel is much lower than that along the channel [97,98] which adds significantly to the contact resistance [99,100]. Therefore, the surface affinity of the SAM layer can affect the thickness of the OSC film, thus tuning the contact resistance.…”

Temperature gradient approach to grow large, preferentially oriented 6,13-bis(triisopropylsilylethynyl) pentacene crystals for organic thin film transistors

“…[4][5][6] Traditional deposition methods, such as drop-casting, have generally been used to attain polycrystalline TIPS pentacene thin films. 7 These resulting thin films are acutely anisotropic with large gaps in between the crystals, leading to vast variations in OTFT performance. 8 To address this issue, a variety of techniques have been utilized to align the TIPS pentacene crystals and reduce thin film roughness.…”

Solution-grown small-molecule organic semiconductor with enhanced crystal alignment and areal coverage for organic thin film transistors

“…HMDS treatment was utilized to passivate the silanol groups on the hydrophilic SiO 2 substrate surface, whereas PFBT treatment was performed to tune the energy level of gold contacts for facilitating hole charge injection. 28 Specifically, HMDS self-assembled monolayers were formed on the gate dielectric via vapor deposition at 140…”