Organic semiconductor

About: Organic semiconductor is a research topic. Over the lifetime, 15905 publications have been published within this topic receiving 533881 citations.

Light-induced bias stress reversal in polyfluorene thin-film transistors

Abstract: Gate bias-stress effects in the high-performance semiconducting polymer poly-9,9′ dioctyl-fluorene-co-bithiophene (F8T2) were studied. The bias stress in F8T2 was characterized in devices having various gate dielectric materials—different types of SiO2 and a polymer—and a variety of chemically modified dielectric/semiconductor interfaces. A bias-stress effect was reversed by illuminating the transistor structure with band gap radiation. The recovery rate was directly related to the absorption characteristics of F8T2. We conclude that bias stress in F8T2 is due to hole charge trapping inside the polymer, close to the dielectric interface and not to a structural change in the polymer, or to charge in the dielectric.

Analog and digital circuits using organic thin-film transistors on polyester substrates

Abstract: We have fabricated and characterized analog and digital circuits using organic thin-film transistors on polyester film substrates. These are the first reported dynamic results for organic circuits fabricated on polyester substrates. The high-performance pentacene transistors yield circuits with the highest reported clock frequencies for organic circuits.

Method for forming a patterned semiconductor film

Abstract: A process for forming a pattern in a semiconductor film is provided. The process comprises the steps of: providing a substrate; providing an organic semiconductor film adjacent the substrate; and providing a destructive agent adjacent selected portions of the organic semiconductor film, the destructive agent changing a property of selected portions of the organic semiconductor film substantially through the full thickness of the organic semiconductor film such that the property of the selected portions of the organic semiconductor film differs from the property of remaining portions of the organic semiconductor film. A method for manufacturing a transistor comprises the steps of: providing a substrate; providing a gate electrode adjacent the substrate; providing a gate dielectric adjacent the substrate and the gate electrode; providing a source electrode and a drain electrode adjacent the gate dielectric; providing a mask adjacent the gate dielectric in a pattern such that the source electrode, the drain electrode, and a portion of the gate dielectric remain exposed; and providing a semiconductor layer comprising one of an organic semiconductor and a plurality of inorganic colloidal particles, adjacent the source electrode, the drain electrode, the portion of the gate dielectric and the mask, thereby forming the transistor, the semiconductor layer having a thickness less than a thickness of the mask.

Entropy of Charge Separation in Organic Photovoltaic Cells: The Benefit of Higher Dimensionality

Abstract: The role of entropy in charge separation processes is discussed with respect to the dimensionality of the organic semiconductor. In 1-D materials, the change in entropy, ΔS, plays no role, but at higher dimensions, it leads to a substantial decrease in the Coulomb barrier for charge separation. The effects of ΔS are highest in equilibrium systems but decrease and become time-dependent in illuminated organic photovoltaic (OPV) cells. Higher-dimensional semiconductors have inherent advantages for charge separation, and this may be one reason that C60 and its derivatives, the only truly three-dimensional organic semiconductors yet known, play such an important role in OPV cells.

Band structure engineering in organic semiconductors

Abstract: A key breakthrough in modern electronics was the introduction of band structure engineering, the design of almost arbitrary electronic potential structures by alloying different semiconductors to continuously tune the band gap and band-edge energies. Implementation of this approach in organic semiconductors has been hindered by strong localization of the electronic states in these materials. We show that the influence of so far largely ignored long-range Coulomb interactions provides a workaround. Photoelectron spectroscopy confirms that the ionization energies of crystalline organic semiconductors can be continuously tuned over a wide range by blending them with their halogenated derivatives. Correspondingly, the photovoltaic gap and open-circuit voltage of organic solar cells can be continuously tuned by the blending ratio of these donors.