Electro-optical circuits based on light-sensing ambipolar organic field-effect transistors

Published versio

Oxygen induced p-doping of alpha-nickel phthalocyanine vacuum sublimed films: Implication for its use in organic photovoltaics

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Energy quantization in solution-processed layers of indium oxide and their application in resonant tunneling diodes

\u3cp\u3eThe formation of quantized energy states in ultrathin layers of indium oxide (In\u3csub\u3e2\u3c/sub\u3eO\u3csub\u3e3\u3c/sub\u3e) grown via spin coating and thermally annealed at 200°C in air is studied. Optical absorption measurements reveal a characteristic widening of the optical band gap with reducing In\u3csub\u3e2\u3c/sub\u3eO\u3csub\u3e3\u3c/sub\u3e layer thickness from ≈43 to ≈3 nm in agreement with theoretical predictions for an infinite quantum well. Through sequential deposition of In\u3csub\u3e2\u3c/sub\u3eO\u3csub\u3e3\u3c/sub\u3e and gallium oxide (Ga\u3csub\u3e2\u3c/sub\u3eO\u3csub\u3e3\u3c/sub\u3e) layers, superlattice-like structures with controlled dimensionality and spatially varying conduction band characteristics are demonstrated. This simple method is then explored for the fabrication of functional double-barrier resonant tunneling diodes. Nanoscale current mapping analysis using conductive atomic force microscopy reveals that resonant tunneling is not uniform but localized in specific regions of the apparent device area. The latter observation is attributed to variation in the layer(s) thickness of the In\u3csub\u3e2\u3c/sub\u3eO\u3csub\u3e3\u3c/sub\u3e quantum well and/or the Ga\u3csub\u3e2\u3c/sub\u3eO\u3csub\u3e3\u3c/sub\u3e barrier layers. Despite the nonidealities, the tremendous potential of solution-processable oxide semiconductors for the development of quantum effect devices that have so far been demonstrated only via sophisticated growth techniques is demonstrated.\u3c/p\u3

Influence of O2 on rectification properties of Nickel Phthalocyanine thin film devices

Thin sandwich film structure devices of Gold/Nickel Phthalocyanine/Lead (Au/NiPc/Pb) were fabricated employing a novel in-situ method. Electrical measurements were performed prior to, and after exposure of the samples to dry air. Under forward bias and for low applied voltages an ohmic conduction was evident, followed by SCLC in the higher voltage range. In the reverse bias, devices were found to exhibit weak rectifying properties originated mainly from the bulk of the NiPc layer. After exposure of the sample to dry air for five days a strong rectifying effect at the NiPc/Pb interface was evident. The phenomenon is believed to be associated with a change of NiPe work function as result of O2 adsorption on the NiPe layer. To verify this a second sample of the type Au/NiPcO2/Pb was fabricated. Electrical characterization of the sample showed stronger rectifying properties providing further experimental evidence on the influence of 02 adsorption on the organic layer. Potential barrier height and diode ideality factor for both NiPc/Pb, and NiPcO2/Pb interfaces after exposure to dry air, were also calculated

Air-stable ambipolar organic transistors

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Electronic Building Permission System: The Case of Greece

AbstractElectronic building permission systems have been used in several European countries from the early 70s (i.e. Italy, France and Netherlands), while in USA are being utilized several components and sub-modules of the system from the early 30s. The European Commission defined the electronic application for Building Permission as one of the 20 primary e-Government services, which each European Member State was obliged to deliver online by 2005, according to the e-Europe strategies (e-Europe2003). However, Greece, as well as several other European countries failed to address this challenge and the goal of an electronic building permission system across Europe was extended, initially until 2010 (i2010 strategy) and eventually until 2020 (Horizon 2020 strategy).The current study initially defines the primary and secondary functionalities that such a system should have. Furthermore, the study examines the factors that influence the success or failure of such a project and proceed to a case study investigation in Greece by examining the current situation and the level of absorption of the European i2010 strategy regarding the electronic building permission.The research framework encompasses a literature survey of publications and official reports in order to shape a “clear picture” regarding the different approach of e-service delivery. In addition, in this paper are analyzed the results of structured questionnaires that have been sent and of interviews that have been conducted with public organizations in Greece that are responsible for the implementation, installation and utilization of such a system (i.e. Information Society in Greece, Municipalities).In conclusion, this research investigates the framework of the building permission e-services and its current situation in Greece that leads to: (a) an effective public management administration by simplification of licensing procedures, (b) a reduction of depraved behavior and (c) environmental benefits by reducing bureaucracy