Charge carrier transport in organic semiconductors
TL;DR: In this article, a brief review is given on different experimental methods that can either directly measure charge carrier mobilities, or at least lead to an estimate, for high purity single crystals, a steep increase of mobilities towards low temperature with the consequence of nonlinear transport and final velocity saturation at elevated electric fields has been traced back to temperature-dependent electron and hole masses approaching the free electron mass at low temperature.
About: This article is published in Synthetic Metals.The article was published on 2003-03-13. It has received 579 citations till now. The article focuses on the topics: Saturation velocity & Charge carrier.
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TL;DR: Electronic Coupling in Oligoacene Derivatives: Factors Influencing Charge Mobility, and the Energy-Splitting-in-Dimer Method 3.1.
Abstract: 2.2. Materials 929 2.3. Factors Influencing Charge Mobility 931 2.3.1. Molecular Packing 931 2.3.2. Disorder 932 2.3.3. Temperature 933 2.3.4. Electric Field 934 2.3.5. Impurities 934 2.3.6. Pressure 934 2.3.7. Charge-Carrier Density 934 2.3.8. Size/molecular Weight 935 3. The Charge-Transport Parameters 935 3.1. Electronic Coupling 936 3.1.1. The Energy-Splitting-in-Dimer Method 936 3.1.2. The Orthogonality Issue 937 3.1.3. Impact of the Site Energy 937 3.1.4. Electronic Coupling in Oligoacene Derivatives 938
3,635 citations
TL;DR: In this article, a review of π-conjugated polymeric semiconductors for organic thin-film (or field effect) transistors (OTFTs or OFETs) and bulk-heterojunction photovoltaic (or solar) cell (BHJ-OPV or OSC) applications are summarized and analyzed.
Abstract: The optoelectronic properties of polymeric semiconductor materials can be utilized for the fabrication of organic electronic and photonic devices. When key structural requirements are met, these materials exhibit unique properties such as solution processability, large charge transporting capabilities, and/or broad optical absorption. In this review recent developments in the area of π-conjugated polymeric semiconductors for organic thin-film (or field-effect) transistors (OTFTs or OFETs) and bulk-heterojunction photovoltaic (or solar) cell (BHJ-OPV or OSC) applications are summarized and analyzed.
2,076 citations
TL;DR: New approaches to add functionality were developed to improve the processability of these materials in solution, allowing the synthesis of acenes larger than pentacene, which have hitherto been largely unavailable and poorly studied.
Abstract: Acenes have long been the subject of intense study because of the unique electronic properties associated with their pi-bond topology. Recent reports of impressive semiconductor properties of larger homologues have reinvigorated research in this field, leading to new methods for their synthesis, functionalization, and purification, as well as for fabricating organic electronic components. Studies performed on high-purity acene single crystals revealed their intrinsic electronic properties and provide useful benchmarks for thin film device research. New approaches to add functionality were developed to improve the processability of these materials in solution. These new functionalization strategies have recently allowed the synthesis of acenes larger than pentacene, which have hitherto been largely unavailable and poorly studied, as well as investigation of their associated structure/property relationships.
1,741 citations
1,713 citations
TL;DR: This paper demonstrates an inverter, a NAND gate, a static random access memory, and a five-stage ring oscillator based on a direct-coupled transistor logic technology based on the semiconducting nature of molybdenum disulfide.
Abstract: Two-dimensional (2D) materials, such as molybdenum disulfide (MoS2), have been shown to exhibit excellent electrical and optical properties. The semiconducting nature of MoS2 allows it to overcome the shortcomings of zero-bandgap graphene, while still sharing many of graphene’s advantages for electronic and optoelectronic applications. Discrete electronic and optoelectronic components, such as field-effect transistors, sensors, and photodetectors made from few-layer MoS2 show promising performance as potential substitute of Si in conventional electronics and of organic and amorphous Si semiconductors in ubiquitous systems and display applications. An important next step is the fabrication of fully integrated multistage circuits and logic building blocks on MoS2 to demonstrate its capability for complex digital logic and high-frequency ac applications. This paper demonstrates an inverter, a NAND gate, a static random access memory, and a five-stage ring oscillator based on a direct-coupled transistor logic...
1,555 citations
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1,112 citations
TL;DR: The drift mobilities of electrons and holes in anthracene crystals have been measured using a pulsed photoconductivity technique as mentioned in this paper, and the results indicate that the charge carriers are not produced in the interior of the crystal, but that they are released from a surface layer of a crystal either directly by photons or by excitons which migrate to the surface.
Abstract: The drift mobilities of electrons and holes in anthracene crystals have been measured using a pulsed photoconductivity technique. The mobilities found at room temperature vary from about 0.3 ${\mathrm{cm}}^{2}$/volt sec to about 3 ${\mathrm{cm}}^{2}$/volt sec, depending on the crystal orientation, and the mobilities increase as the temperature is lowered. The wavelength dependence of the number of charge carriers produced by a pulse of light, as well as other experimental data, indicates that the charge carriers are not produced in the interior of anthracene crystals, but that they are released from a surface layer of the crystal either directly by photons or by excitons which migrate to the surface.
527 citations
TL;DR: In this article, the data of E. J. Ryder on the mobility of electrons in electric fields up to 40,000 volts per cm are analyzed and it is estimated that electron “temperatures as high as 4000°K have been produced in specimens having temperatures of atomic vibration of 300° K.
Abstract: The data of E. J. Ryder on the mobility of electrons in electric fields up to 40,000 volts per cm are analyzed. The mobility decreases many fold due to the influence of scattering by optical modes and due to increases of electron energy. It is estimated that electron “temperatures” as high as 4000°K have been produced in specimens having temperatures of atomic vibration of 300° K. The critical drift velocity above which there are deviations from Ohm's law is about 2.6 × 106 cm/sec. This is three times higher than the elementary theory and on explanation in terms of complex energy surfaces is proposed.
416 citations
TL;DR: Organic field-effect transistors based on pentacene single crystals, prepared with an amorphous aluminum oxide gate insulator, are capable of ambipolar operation and can be used for the preparation of complementary inverter circuits.
Abstract: Organic field-effect transistors based on pentacene single crystals, prepared with an amorphous aluminum oxide gate insulator, are capable of ambipolar operation and can be used for the preparation of complementary inverter circuits. The field-effect mobilities of carriers in these transistors increase from 2.7 and 1.7 square centimeters per volt per second at room temperature up to 1200 and 320 square centimeters per volt per second at low temperatures for hole and electron transport, respectively, following a power-law dependence. The possible simplification of the fabrication process of complementary logic circuits with these transistors, together with the high carrier mobilities, may be seen as another step toward applications of plastic electronics.
361 citations
TL;DR: In this article, a method was developed to estimate the field effect mobility of organic field effect transistors for the contact series resistance, which was found to increase by a factor of nearly 100 from quaterthiophene to octithiophene.
Abstract: Organic field-effect transistors, in which the active semiconductor is made of oligothiophenes of various lengths, have been fabricated and characterized. A method is developed to estimate the field-effect mobility μ corrected for the contact series resistance. The mobility is found to increase by a factor of nearly 100 from quaterthiophene (4T) to octithiophene (8T). More importantly, μ increases quasilinearly with gate voltage. The origin of this gate bias dependence is discussed. One explanation could be the presence of traps that limit charge transport. Alternatively, the gate-voltage dependence is tentatively attributed to a dependence of the mobility with the concentration of carriers in the accumulation layer.
295 citations