Organic semiconductor

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

Pentacene TFT with improved linear region characteristics using chemically modified source and drain electrodes

Abstract: We have fabricated pentacene active layer organic thin film transistors (OTFTs) using chemically-modified source and drain contacts with improved contact and linear region characteristics. OTFTs fabricated on heavily doped, thermally oxidized single-crystal silicon substrates have linear field-effect mobility greater than 0.5 cm/sup 2//V-s at a drain-source voltage of -0.1 V, on/off current ratio greater than 10/sup 7/, and subthreshold slope as low as 0.7 V/decade.

Nanostructured Hybrid Polymer−Inorganic Solar Cell Active Layers Formed by Controllable in Situ Growth of Semiconducting Sulfide Networks

Abstract: Nanostructured composites of inorganic and organic materials are attracting extensive interest for electronic and optoelectronic device applications. In this paper, we introduce a general method for the fabrication of metal sulfide nanoparticle/polymer films employing a low-cost and low temperature route compatible with large-scale device manufacturing. Our approach is based upon the controlled in situ thermal decomposition of a solution processable metal xanthate precursor complex in a semiconducting polymer film. To demonstrate the versatility of our method, we fabricate a CdS/P3HT nanocomposite film and show that the metal sulfide network inside the polymer film assists in the absorption of visible light and enables the achievement of high yields of charge photogeneration at the CdS/P3HT heterojunction. Photovoltaic devices based upon such nanocomposite films show solar light to electrical energy conversion efficiencies of 0.7% under full AM1.5 illumination and 1.2% under 10% incident power, demonstrating the potential of such nanocomposite films for low-cost photovoltaic devices.

Dopant density determination in disordered organic field-effect transistors

Abstract: We demonstrate that, by using a concentric device geometry, the dopant density and the bulk charge-carrier mobility can simultaneously be estimated from the transfer characteristics of a single disordered organic transistor. The technique has been applied to determine the relation between the mobility and the charge density in solution-processed poly(2,5-thienylene vinylene) and poly(3-hexyl thiophene) thin-film field-effect transistors. The observation that doping due to air exposure takes place already in the dark, demonstrates that photoinduced oxygen doping is not the complete picture.

Solution-Processed Bulk-Heterojunction Solar Cells Based on Monodisperse Dendritic Oligothiophenes†

Abstract: A novel family of soluble conjugated dendritic oligothiophenes (DOTs) as monodisperse 3D macromolecular architectures was characterized with respect to optical and redox properties in solution and in solid films. Band gaps of 2.5-2.2 eV, typical for organic semiconductors, were determined as well as HOMO/LUMO energy levels ideal for efficient electron transfer to acceptors such as [6,6]-phenyl-C 61 -butyric acid methyl ester (PCBM) identifying them as suitable materials for solar cell applications. Solution-processed bulk-heterojunction solar cells using DOTs as electron donor and PCBM as acceptor were prepared and investigated. High open-circuit voltages V oc of 1.0 V and power-conversion efficiencies up to 1.72% were obtained for the DOT-based devices. The higher generations DOTs provide the highest efficiencies. Based on the monodispersity of the DOTs, an analysis of the molar ratio between donor and acceptor in the blended film was possible leading to an optimal value of five to six thiophene units per PCBM.

Organic and Nano-Structured Composite Photovoltaics: An Overview

Abstract: Organic photovoltaic devices are poised to fill the low-cost, low power niche in the solar cell market Recently measured efficiencies of solid-state organic cells are nudging 5% while Gratzel’s more established dye-sensitized solar cell technology is more than double this A fundamental understanding of the excitonic nature of organic materials is an essential backbone for device engineering Bound electron-hole pairs,“excitons,” are formed in organic semiconductors on photo-absorption In the organic solar cell, the exciton must diffuse to the donor-accepter interface for simultaneous charge generation and separation This interface is critical as the concentration of charge carriers is high and recombination here is higher than in the bulk Nanostructured engineering of the interface has been utilized to maximize organic materials properties, namely to compensate the poor exciton diffusion lengths and lower mobilities Excitonic solar cells have different limitations on their open-circuit photo-voltages due to these high interfacial charge carrier concentrations, and their behavior cannot be interpreted as if they were conventional solar cells This article briefly reviews some of the differences between excitonic organic solar cells and conventional inorganic solar cells and highlights some of the technical strategies used in this rapidly progressing field, whose ultimate aim is for organic solar cells to be a commercial reality