Organic semiconductor

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

Analytic model of carrier mobility in doped disordered organic semiconductors

Abstract: We suggest an analytic model of charge transport in weakly and heavily doped disordered organic materials. Doping of such materials increases the density of carriers but also creates deep Coulomb traps. The net effect is typically a decreasing mobility at low doping levels. At high doping levels the Coulomb traps overlap spatially, which leads to smoothening of the potential landscape and to strongly increasing mobility. The model is used to fit experimental data on the mobility in electrochemically (EC) doped polythiophenes. It also explains why increasing the carrier density by the field-effect results in a much higher mobility than an equivalent increase of the carrier density by EC doping.

Supramolecular photosensitive and electroactive materials

Abstract: Phthalocyanines: Synthesis, Supramolecular Organization, and Physical Properties Sandwich-Type Phthalocyaninato and Porphyrinato Metal Complexes Electronic Properties of Molecular Organic Semiconductor Thin Films Polydiacetylenes Structural and Optical Properties of Conjugated Molecules in Perhydrotriphenylene (PHTP) and in Other Channel-Forming Inclusion Compounds Charge Transfer Properties of Photosynthetic and Respiratory Proteins Optical and Electronic Properties of Carbon Nitride Polyimides for Microelectronics and Tribology Applications Anomalous Charge Transport and Polarization in Semiconductors Oxides and Porous Film Electrodes Electroactive and Photoactive Dendrimers Electrical Properties of Organic Monolayer Films

High Ambipolar Mobility in a Highly Ordered Smectic Phase of a Dialkylphenylterthiophene Derivative That Can Be Applied to Solution‐Processed Organic Field‐Effect Transistors

Abstract: Since the 1990s, we have witnessed remarkable progress in organic semiconductor technology. [1] In particular, reasonably high carrier mobilities, exceeding those of amorphous silicon, were observed in thin-film transistors fabricated from a single crystal of rubrene. [2] In general, it is difficult to fabricate single crystals of aromatic compounds; therefore, zone-melt and Bridgeman crystal-growth [3] or vacuum crystal-growth techniques [4] are indispensable. Polycrystalline thin films are relatively easy to fabricate and suitable for practical devices. High carrier mobilities—of the order of 1 cm 2 V –1 s –1 —have been observed in field-effect transistor (FET) devices based on polycrystalline pentacene thin films. [5] However, defects and domain boundaries affect the carrier transport in aromatic polycrystalline thin films; therefore, the crystal growth under the vacuum process is rigorously controlled. [6] Device fabrication with a more practical solution process has been investigated. As well as conjugated polymers, [7] precursor methods in which thin films fabricated using soluble precursors are transformed to polycrystalline thin films by thermal treatment, [8] and solution-processable pentacene and anthradithiophene derivatives, which form polycrystalline thin films using a spin-coat method, have been investigated. [9] The field-effect mobilities in these studies are of the order of 10 –2 cm 2 , and the carrier mobility is increased up to 0.1 ≈ 1c m 2 V –1 s –1 by thermal treatment. [8,9] The optimum mobility is lower than those of the FET devices fabricated using vacuum deposition; the device characteristics strongly depend upon the film morphology, because the organic semiconductor thin films fabricated by the solution process have many defects and exhibit low carrier mobility.

Long-range exciton diffusion in molecular non-fullerene acceptors

Abstract: The short exciton diffusion length associated with most classical organic semiconductors used in organic photovoltaics (5-20 nm) imposes severe limits on the maximum size of the donor and acceptor domains within the photoactive layer of the cell. Identifying materials that are able to transport excitons over longer distances can help advancing our understanding and lead to solar cells with higher efficiency. Here, we measure the exciton diffusion length in a wide range of nonfullerene acceptor molecules using two different experimental techniques based on photocurrent and ultrafast spectroscopy measurements. The acceptors exhibit balanced ambipolar charge transport and surprisingly long exciton diffusion lengths in the range of 20 to 47 nm. With the aid of quantum-chemical calculations, we are able to rationalize the exciton dynamics and draw basic chemical design rules, particularly on the importance of the end-group substituent on the crystal packing of nonfullerene acceptors. The short-range diffusion length of organic semiconductors severely limits exciton harvesting and charge generation in organic bulk heterojunction solar cells. Here, the authors report exciton diffusion length in the range of 20 to 47 nm for a wide range of non-fullerene acceptors molecules.