Gate-bias assisted charge injection in organic field-effect transistors

Abstract

Gate-bias assisted charge injection in organic field-effect transistors Brondijk, J. J.; Torricelli, F.; Smits, E. C. P.; Blom, P. W. M.; de Leeuw, D. M. Take-down policy If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim.Downloaded from the University of Groningen/UMCG research database (Pure): http://www.rug.nl/research/portal. For technical reasons the number of authors shown on this cover page is limited to 10 maximum. a b s t r a c tThe charge injection barriers in organic field-effect transistors (OFETs) seem to be far less critical as compared to organic light-emitting diodes (OLEDs). Counter intuitively; we show that the origin is image-force lowering of the barrier due to the gate bias at the source contact; although the corresponding gate field is perpendicular to the channel current. In coplanar OFETs; injection barriers up to 1 eV can be surmounted by increasing the gate bias; enabling extraction of bulk transport parameters in this regime. For staggered transistors; however; the injection is gate-assisted only until the gate bias is screened by the accumulation channel opposite to the source contact. The gate-assisted injection is supported by two-dimensional numerical charge transport simulations that reproduce the gate-bias dependence of the contact resistance and the typical S-shaped output curves as observed for OFETs with high injection barriers.

Unified drain-current model of complementary p- and n-type OTFTs

“…This is evident from the output characteristics shown in Fig. 6 and, according to several studies [51,52,53,54], we verified that it is due to the parasitic contact resistance at the source injecting contact. This is further confirmed by the normalized transfer characteristics shown in Fig.…”

Organic field-effect transistors as a test-bed for molecular electronics: A combined study with large-area molecular junctions

“…Despite the barrier of about 1 eV, the values are comparable to those of bare Au and PFDT treated electrodes. Transistors are tolerant for injection barriers due to the image-force lowering of the barrier caused by the high electric field at the source contact [29]. We added the measured tunnel resistance of HDT molecular junctions to that of renormalized contact resistance using bare Au electrodes.…”

Contactless charge carrier mobility measurement in organic field-effect transistors

“…hole accumulation. The drain current of the transistor with the low work-function contacts (u 2 ) shows a clear s-shape indicative for a hole injection barrier [37]. This is not observed in the transistor with the higher work-function contacts (u 1 ).…”

“…However, the transistor with a hole injection barrier shows only comparable mobilities at significantly higher gate biases. A gate field is known to assist charge injection and therefore contact resistance plays a smaller role at high gate biases [37].…”