Organic semiconductor

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

N-Type 2D Organic Single Crystals for High-Performance Organic Field-Effect Transistors and Near-Infrared Phototransistors.

Abstract: Organic field-effect transistors and near-infrared (NIR) organic phototransistors (OPTs) have attracted world's attention in many fields in the past decades. In general, the sensitivity, distinguishing the signal from noise, is the key parameter to evaluate the performance of NIR OPTs, which is decided by responsivity and dark current. 2D single crystal films of organic semiconductors (2DCOS) are promising functional materials due to their long-range order in spite of only few molecular layers. Herein, for the first time, air-stable 2DCOS of n-type organic semiconductors (a furan-thiophene quinoidal compound, TFT-CN) with strong absorbance around 830 nm, by the facile drop-casting method on the surface of water are successfully prepared. Almost millimeter-sized TFT-CN 2DCOS are obtained and their thickness is below 5 nm. A competitive field-effect electron mobility (1.36 cm2 V-1 s-1 ) and high on/off ratio (up to 108 ) are obtained in air. Impressively, the ultrasensitive NIR phototransistors operating at the off-state exhibit a very low dark current of ≈0.3 pA and an ultrahigh detectivity (D*) exceeding 6 × 1014 Jones because the devices can operate in full depletion at the off-state, superior to the majority of the reported organic-based NIR phototransistors.

Strong and Stable Doping of Carbon Nanotubes and Graphene by MoOx for Transparent Electrodes

Abstract: MoOx has been used for organic semiconductor doping, but it had been considered an inefficient and/or unstable dopant. We report that MoOx can strongly and stably dope carbon nanotubes and graphene. Thermally annealed MoOx-CNT composites can form durable thin film electrodes with sheet resistances of 100 Ω/sq at 85% transmittance plain and 85 Ω/sq at 83% transmittance with a PEDOT:PSS adlayer. Sheet resistances change less than 10% over 20 days in ambient and less than 2% with overnight heating to 300 °C in air. The MoOx can be easily deposited either by thermal evaporation or from solution-based precursors. Excellent stability coupled with high conductivity makes MoOx-CNT composites extremely attractive candidates for practical transparent electrodes.

Organic solar cells with sensitivity extending into the near infrared

Abstract: We describe an organic photovoltaic cell based on a tin(II) phthalocyanine (SnPc)∕C60 donor/acceptor heterojunction with sensitivity at wavelengths of λ>900nm. We find that the low hole mobility in polycrystalline thin films of SnPc, μh=(2±1)×10−10cm2∕Vs, prevents the use of thick layers, leading to low fill factors and therefore low-power conversion efficiencies. However, owing to its large absorption coefficient, a 50-A-thick layer of SnPC yields solar cell external quantum efficiencies of up to 21% at λ=750nm. With the double heterostructure of indium-tin oxide/100A copper phthalocyanine/50A SnPc∕540A C60∕75A bathocuproine/Ag, we obtain a power conversion efficiency of (1.0±0.1)% under 1 sun standard AM1.5G solar illumination and efficiencies of (1.3±0.1)% under intense (10 suns) standard AM1.5G solar illumination.

Electronic transport properties of pentacene single crystals upon exposure to air

Abstract: We report the effect of air exposure on the electronic properties of pentacene single crystals. Air can diffuse reversibly in and out of the crystals and influences the physical properties. We discern two competing mechanisms that modulate the electronic transport. The presence of oxygen increases the hole conduction, as in dark four O2 molecules introduce one charge carrier. This effect is enhanced by the presence of visible light. Contrarily, water, present in ambient air, is incorporated in the crystal lattice and forms trapping sites for injected charges.