Pentacene

About: Pentacene is a research topic. Over the lifetime, 5051 publications have been published within this topic receiving 161481 citations. The topic is also known as: 2,3:6,7-dibenzanthracene & benzo[b]naphthacene.

Anisotropic mobility in large grain size solution processed organic semiconductor thin films

Abstract: The hollow pen method for writing thin films of materials from solution is utilized to deposit films of 6,13-bis(tri-isopropylsilylethynyl) pentacene (TIPS pentacene) onto SiO2 surfaces with pre-patterned source/drain gold contacts. We demonstrate that large domains are obtained for TIPS pentacene films deposited from 0.5–4.0wt% solutions with toluene. Crystalline grains with (001) orientation are observed to grow with sizes that can exceed 1mm along the writing direction. A preferred azimuthal orientation is also selected by the process, resulting in anisotropic field effect transistor mobility in the films.

Structural and Electrostatic Complexity at a Pentacene/Insulator Interface

Abstract: The properties of organic-semiconductor/insulator (O/I) interfaces are critically important to the operation of organic thin-film transistors (OTFTs) currently being developed for printed flexible electronics. Here we report striking observations of structural defects and correlated electrostatic-potential variations at the interface between the benchmark organic semiconductor pentacene and a common insulator, silicon dioxide. Using an unconventional mode of lateral force microscopy, we generate high-contrast images of the grain-boundary (GB) network in the first pentacene monolayer. Concurrent imaging by Kelvin probe force microscopy reveals localized surface-potential wells at the GBs, indicating that GBs will serve as charge-carrier (hole) traps. Scanning probe microscopy and chemical etching also demonstrate that slightly thicker pentacene films have domains with high line-dislocation densities. These domains produce significant changes in surface potential across the film. The correlation of structural and electrostatic complexity at O/I interfaces has important implications for understanding electrical transport in OTFTs and for defining strategies to improve device performance.

A photopatternable pentacene precursor for use in organic thin-film transistors.

Abstract: We demonstrate that modifying pentacene to incorporate an acid-labile moiety into its molecular structure leads to a new precursor that can be easily deposited, photopatterned, and processed via wet-chemical methods to produce organic semiconducting devices exhibiting good electrical characteristics. Acidic conditions produced by ultraviolet illumination of a co-deposited photoacid generator greatly accelerate the local conversion of this N-sulfinyl-tert-butylcarbamate pentacene adduct back to pentacene. Photopatterned thin-film transistors exhibit carrier mobilities in excess of 0.1 cm2 V-1 s-1, making this an attractive precursor for fabrication of large-area organic electronics via solution-phase methods.

Morphological and Transistor Studies of Organic Molecular Semiconductors with Anisotropic Electrical Characteristics

Abstract: Oriented thin films of organic semiconducting small molecules were prepared by crystallization on rubbed alignment layers. Polarized absorption spectra showed that the long axis of the conjugated backbones was highly oriented along the rubbing direction and parallel to the substrates. Transmission electron microscopy and diffraction confirmed that the molecules and in many cases the resulting crystals are aligned. Using the above aligned films as semiconducting layers, we fabricated field-effect transistors having anisotropic mobilities with ratios greater than 15. Several common organic semiconductors have been investigated, and the results indicate that this growth method is generally successful for achieving macroscopic alignment of these semiconducting molecules (and frequently their crystals, as well).

Tunable Crystal Nanostructures of Pentacene Thin Films on Gate Dielectrics Possessing Surface-Order Control†

Abstract: To enhance the electrical performance of pentacene-based field-effect transistors (FETs) by tuning the surface-induced ordering of pentacene crystals, we controlled the physical interactions at the semiconductor/gate dielectric (SiO2) interface by inserting a hydrophobic self-assembled monolayer (SAM, CH3-terminal) of organoalkyl-silanes with an alkyl chain length of C8, C12, C16, or C18, as a complementary interlayer. We found that, depending on the physical structure of the dielectric surfaces, which was found to depend on the alkyl chain length of the SAM (ordered for C18 and disordered for C8), the pentacene nano-layers in contact with the SAM could adopt two competing crystalline phases—a “thin-film phase” and “bulk phase” – which affected the π-conjugated nanostructures in the ultrathin and subsequently thick films. The field-effect mobilities of the FET devices varied by more than a factor of 3 depending on the alkyl chain length of the SAM, reaching values as high as 0.6 cm2 V−1 s−1 for the disordered SAM-treated SiO2 gate-dielectric. This remarkable change in device performance can be explained by the production of well π-conjugated and large crystal grains in the pentacene nanolayers formed on a disordered SAM surface. The enhanced electrical properties observed for systems with disordered SAMs can be attributed to the surfaces of these SAMs having fewer nucleation sites and a higher lateral diffusion rate of the first seeding pentacene molecules on the dielectric surfaces, due to the disordered and more mobile surface state of the short alkyl SAM.