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.

Dependency of organic phototransistor properties on the dielectric layers

Abstract: Organic phototransistors with pentacene semiconductor and Ta2O5 or polymethyl methacrylate (PMMA) dielectric layer have been investigated. It was found that the phototransistor properties strongly depend on the dielectric layer. Under a broadband light with 10mW∕cm2, the sensitivity of the Ta2O5 based transistor is much higher than that of the PMMA based transistor. For Ta2O5 based transistor, the photosensitivity (the ratio of photocurrent to dark current) and the threshold voltage shift are 4000 and 13.5V, respectively. While for PMMA based transistor, the corresponding values are only 0.5 and 2.9V, respectively. That large difference is attributed to the electron trapping ability of Ta2O5.

Structure, morphology, and growth dynamics of perfluoro-pentacene thin films

Abstract: We report high structural order in thin films of the organic semiconductor perfluoro-pentacene (PFP), which is a candidate material for n-type applications, deposited by vacuum sublimation on oxidized silicon wafers. Bragg reflections up to high order in both specular and grazing incidence geometries and a mosaicity of less than 0.01° demonstrate the well defined structure. The thin film entirely consists of crystallites with a structure close to the bulk phase without any contamination with a second phase. Real-time X-ray measurements show that PFP grows in a Stranski–Krastanov growth mode with the first monolayer wetting the substrate before 3d-growth sets in during growth of the second monolayer. Implications for its use are discussed. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Improvement in open circuit voltage of organic solar cells by inserting a thin phosphorescent iridium complex layer

Abstract: The authors develop organic solar cells (OSCs) with a multicharge separation (MCS)interface by inserting ∼ 4 nm thin layer of phosphorescent bis(2-(4-tertbutylphenyl) benzothiazolato- N , C 2 , ) iridium (acetylacetonate) ( t-bt ) 2 Ir ( acac ) comparing with copper phthalocyanine (CuPc) between pentacene/ C 60 heterojunction. The result showed that open circuit voltage is remarkably enhanced without obviously changing external quantum efficiency η EQE and short-circuit current density. As a result, power conversion efficiency is improved from 1.53% for pentacene/ C 60 device to 1.83% with sandwich layer ( t-bt ) 2 Ir ( acac ) and 1.98% with CuPc. Moreover, a suitable equivalent circuit model is proposed to intuitively reveal the inner photogeneration process of OSC with MCSinterface.

Improved performance of pentacene field-effect transistors using a polyimide gate dielectric layer

Abstract: Organic field-effect transistors using pentacene have been fabricated employing polyimide gate dielectric layers. The root-mean square surface roughness of polyimide films is 9 A. Devices with thin polyimide films as gate achieved a mobility of 0.16 cm2 V−1 s−1, threshold voltage −6.4 V, on–off ratio ~ 104 and subthreshold slope 7.5 dec−1 with the gate voltage span between 0 and −30 V. The upper limit of interface trap density has been estimated to be 3.9 × 1012 cm−2 eV−1. The mobility is found to be gate bias dependent.

Engineering density of semiconductor-dielectric interface states to modulate threshold voltage in OFETs

Abstract: Threshold-voltage control is critical to the further development of pentacene organic field-effect transistors (OFETs). In this paper, we demonstrate that the threshold voltage can be tuned through chemical treatment of the gate dielectric layer. We show that oxygen plasma treatment of an organic polymer gate dielectric, parylene, introduces traps at the semiconductor-dielectric interface that strongly affect the OFET performance. Atomic force microscopy, optical microscopy using crossed-polarizers, and current-voltage and capacitance-voltage characterization were performed on treated and untreated devices. A model is presented to account for the effects of trap-introduced charges, both 1) fixed charges (2.0/spl times/10/sup -6/ C/cm/sup 2/) that shift the threshold voltage from -17 to +116 V and 2) mobile charges (1.1/spl times/10/sup -6/ C/cm/sup 2/) that increase the parasitic bulk conductivity. This technique offers a potential method of tuning threshold voltage at the process level.