ZnO/Poly(3,4-ethylenedioxythiophene) Poly(styrenesulfonate) Based Ultraviolet and Visible Photodetectors: Role of Defects

Here, we report the ZnO/poly(3,4-ethylenedioxythiophene) poly(styrenesulfonate) (PEDOT:PSS) based photodetectors that can response to ultraviolet as well as visible light. The temporal response of the heterostructures for various excitations in the ultraviolet (UV) and visible range are performed. The time constants are found to be excitation-dependent, the response to visible light is better as compared to UV. The reason behind the better response to UV light is the high level of defects present in ZnO as confirmed by the photoluminescence (PL) measurements. This is corroborated by the time resolved fluorescence (TRF) measurements which provides sufficient information behind the slow response time under the UV excitations. The possible explanation being the non-radiative recombinations occurring due to the traps or impurities present in the film which slows down the photoresponse.

Surface morphology, optical properties and conductivity changes of poly(3,4-ethylenedioxythiophene): poly(styrenesulfonate) by using additives

The optical properties and electrical conductivity of highly conducting poly(3,4-ethylenedioxythiophene) (PEDOT) doped with poly(styrenesulfonate) (PSS) are reported as a function of the processing additive conditions. The addition of dimethyl sulfoxide (DMSO) increases the conductivity and modifies the dielectric response as observed from the ellipsometric studies. Also the surface roughness and morphology change with the composition of PEDOT: PSS: DMSO and film deposition conditions. The real part of the dielectric function becomes negative in highly conducting samples, indicating the presence of delocalized charge carriers. The real and imaginary parts of the refractive index were determined as a function of wavelength. The results are consistent with the increase in conductivity upon the addition of DMSO.

Fabrication of a novel biomaterial with enhanced mechanical and conducting properties

Conducting polymers have the combined advantages of metal conductivity with ease in processing and biocompatibility; making them extremely versatile for biosensor and tissue engineering applications. However, the inherent brittle property of conducting polymers limits their direct use in such applications which generally warrant soft and flexible material responses. Addition of fillers increases the material compliance, but is achieved at the cost of reduced electrical conductivity. To retain suitable conductivity without compromising the mechanical properties, we fabricate an electroactive blend (dPEDOT) using low grade PEDOT: PSS as the base conducting polymer with polyvinyl alcohol as filler and glycerol as a dopant. Bulk dPEDOT films show a thermally stable response till 110 degrees C with over seven fold increase in room temperature conductivity as compared to 0.002 S cm(-1) for pristine PEDOT: PSS. We characterize the nonlinear stress-strain response of dPEDOT, well described using a Mooney-Rivlin hyperelastic model, and report elastomer-like moduli with ductility similar to fives times its original length. Dynamic mechanical analysis shows constant storage moduli over a large range of frequencies with corresponding linear increase in tan(delta). We relate the enhanced performance of dPEDOT with the underlying structural constituents using FTIR and AFM microscopy. These data demonstrate specific interactions between individual components of dPEDOT, and their effect on surface topography and material properties. Finally, we show biocompatibility of dPEDOT using fibroblasts that have comparable cell morphologies and viability as the control, which make dPEDOT attractive as a biomaterial.

New low band gap 2-(4-(trifluoromethyl)phenyl)-1H-benzod]imidazole and benzo1,2-c; 4,5-c `]bis1,2,5]thiadiazole based conjugated polymers for organic photovoltaics

Two new low band gap D-A structured conjugated polymers, PBDTTBI and PBDTBBT, based on 2-(4-(trifluoromethyl)phenyl)-1H-benzod]imidazole and benzo1,2-c; 4,5-c']bis1,2,5]thiadiazole acceptor units with benzo1,2-b; 3,4-b']dithiophene as a donor unit have been designed and synthesized via a Stille coupling reaction. The incorporation of the benzo1,2-c; 4,5-c']bis1,2,5]thiadiazole unit into PBDTBBT has significantly altered the optical and electrochemical properties of the polymer. The optical band gap estimated from the onset absorption edge is similar to 1.88 eV and similar to 1.1 eV, respectively for PBDTTBI and PBDTBBT. It is observed that PBDTBBT exhibited a deeper HOMO energy level (similar to 4.06 eV) with strong intramolecular charge transfer interactions. Bulk heterojunction solar cells fabricated with a configuration of ITO/PEDOT: PSS/PBDTBBT: PC71BM/Al exhibited a best power conversion efficiency of 0.67%, with a short circuit current density of 4.9 mA cm(-2), an open-circuit voltage of 0.54 V and a fill factor of 25%.

Efficient charge transfer and field-induced tunneling transport in hybrid composite device of organic semiconductor and cadmium telluride quantum dots

Temperature and photo-dependent current-voltage characteristics are investigated in thin film devices of a hybrid-composite comprising of organic semiconductor poly(3,4-ethylenedioxythiophene): polystyrenesulfonate (PEDOT: PSS) and cadmium telluride quantum dots (CdTe QDs). A detailed study of the charge injection mechanism in ITO/PEDOT: PSS-CdTe QDs/Al device exhibits a transition from direct tunneling to Fowler-Nordheim tunneling with increasing electric field due to formation of high barrier at the QD interface. In addition, the hybrid-composite exhibits a huge photoluminescence quenching compared to aboriginal CdTe QDs and high increment in photoconductivity (similar to 400%), which is attributed to the charge transfer phenomena. The effective barrier height (Phi(B) approximate to 0.68 eV) is estimated from the transition voltage and the possible origin of its variation with temperature and photo-illumination is discussed. (C) 2015 AIP Publishing LLC.

The Key Factors In Fabrication Of High-Quality Ordered Macroporous Copper Film

The template-directed fabrication of highly-ordered porous film is of significant importance in implementation of the photonic band gap structure. The paper reports a simple and effective method to improve the electrodeposition of metal porous film by utilizing highly-ordered polystyrene spheres (PSs) template. By surface-modification method, the hydrophobic property of the PSs template surfaces was changed into hydrophilic one. It was demonstrated that the surface modi. cation process enhanced the permeability of the electrolyte solution in the nanometer-sized voids of the colloidal template. The homogeneously deposited copper film with the highly-ordered voids in size of less than 500 nm was successfully obtained. In addition, it was found that large defects, such as microcracks in the template, strongly influenced the macroporous films quality. An obvious preferential growth in the cracked area was observed. (C) 2008 Elsevier B. V. All rights reserved.

Occurrence of whale sharks in coastal waters in the Indian Ocean: an interesting coincidence

Salinity, temperature and pressure are parameters which govern the oceanographic state of a marine water body and together they make up density of seawater. In this contribution we will focus our interest on one of these parameters, the salinity: accuracy in relation to different purposes as well as observation technique and instrumentation. We will also discuss the definition of salinity. For example most of the Indian Ocean waters are within the salinity range from 34.60-34.80, which emphasize the importance of careful observations and clear definitions of salinity, in such a way that it is possible to define water masses and predict their movements. In coastal waters the salinity usually features much larger variation in time and space and thus less accuracy is sometimes needed. Salinity has been measured and defined in several ways over the past century. While early measurements were based on the amount of salt in a sea water sample, today the salinity of seawater is most often determined from its conductivity. As conductivity is a function of salinity and temperature, determination involves also measurement of the density of seawater is now more precisely estimated and thus the temperature. As a result of this method the Practical Salinity Scale (PSS) was developed. The best determination of salinity from conductivity and the temperature measurements gives salinity with resolution of 0.001 psu, while the accuracy of titration method was about ± 0.02‰. Because of that, even calculation of movements in the ocean is also improved.

Product Service Systems and supply network relationships: An exploratory case study

Purpose - In recent years there has been increasing interest in Product Service Systems (PSSs) as a business model for selling integrated product and service offerings. To date, there has been extensive research into the benefits of PSS to manufacturers and their customers, but there has been limited research into the effect of PSS on the upstream supply chain. This paper seeks to address this gap in the research. Design/methodology/approach - The research uses case-based research which is appropriate for exploratory research of this type. In-depth interviews were conducted with key personnel in a focal firm and two members of its supply chain, and the results were analysed to identify emergent themes.b Findings - The research has identified differences in supplier behaviour dependent on their role in PSS delivery and their relationship with the PSS provider. In particular, it suggests that for a successful partnership it is important to align the objectives between PSS provider and suppliers. Originality/value - This research provides a detailed investigation into a PSS supply chain and highlights the complexity of roles and relationships among the organizations within it. It will be of value to other PSS researchers and organizations transitioning to the delivery of PSS. © Emerald Group Publishing Limited.

Strategies for designing and developing services for manufacturing firms

Product/service-systems (PSS) are in effect an approach to designing integrated products and services with a focus on both customer and product life cycle activities. A range of service-oriented design strategies can be found in current literature, from product-oriented DfX approaches to more customer-oriented approaches, such as integrated solutions. In this article, design strategies related to different types of services are mapped. Case studies from two industrial companies are used to confront the existing literature in order to improve the understanding of how manufacturing companies may align their product and service development activities with their business strategies. © 2010.

Influencing factors of successful transitions towards product-service systems: A simulation approach

Product-Service Systems (PSS) are new business strategies moving and extending the product value towards its functional usage and related required services. From a theoretical point of view the PSS concept is known since a decade and many Authors reported reasonable possible success factors: higher profits over the entire life-cycle, diminished environmental burden, and localization of required services. Nevertheless the PSS promises remain quantitatively unproven relaying on a simple theory that involves a few constructs with some empirical grounding, but that is limited by weak conceptualization, few propositions, and/or rough underlying theoretical logic. A plausible interpretation to analyze the possible evolution of a PSS strategy could be considering it as a new business proposition competing on a traditional Product-Oriented (PO) market, assumed at its own equilibrium state at a given time. The analysis of the dynamics associated to a possible transition from a traditional PO to a PSS strategy allows investigating the main parameters and variables influencing an eventual successful adoption. This research is worthwhile because organizations undergoing fundamental PSS strategy are concerned about change and inertia key processes which, despite equilibrium theory and because of negative feedback loops, could undermine, economically, the return of their PSS proposition. In this paper Authors propose a qualitative System Dynamics (SD) approach by considering the PSS as a perturbation of an existing PO market featured by a set of known parameters. The proposed model incorporates several PSS factors able to influence the success of a PSS proposition under a set of given and justified assumptions, attempting to place this business strategy in a dynamic framework.

A framework for designing product service systems

In this competitive globalizing scenario, manufacturers are adopting a strategy of bundling products and services into an integrated solution to create sustainable competitive advantage. Servitizing manufacturers are increasingly transforming their processes and practices to build product-service systems (PSS). During this transformation they require substantial support to face stringent challenges. Research in the PSS domain is heading towards the development of a design theory and methodology that facilitates the systematic creation of viable PSS conceptual designs. In this paper, various proposed design methods are reviewed and research gaps are summarized. Primarily, it has been observed that the importance of the capabilities of the stakeholders involved in designing PSS has not been noted in the proposed methods. Regarding this capability view point, a framework for designing PSS has been proposed. This framework highlights the important features required in designing PSS such as co-creation, responsibilities and competences. Every step in the framework has been explained with a case study involving laser systems used for manufacturing cutting operation.

Defining product-service network configurations and location roles: A current and future state analysis framework for international engineering operations

Many manufacturing firms have developed a service dimension to their product portfolio. In response to this growing trend of servitisation, organisations, often involved in complex, long-lifecycle product-service system (PSS) provision, need to reconfigure their global engineering networks to support integrated PSS offerings. Drawing on parallel concepts in 'production' networks, the idea of 'location role' now becomes increasingly complex, in terms of service delivery. As new markets develop, locations in a specific region may need to grow/adapt engineering service 'competencies' along the value chain, from design and build to support and service, in order to serve future location-specific requirements and, potentially, those requirements of the overall network. The purpose of this paper is to advance understanding of how best to design complex multi-organisational engineering service networks, through extension of the 'production' network location role concept to a PSS context, capturing both traditional engineering 'design and build' and engineering 'service' requirements. Copyright © 2012 Inderscience Enterprises Ltd.

A highly conductive and transparent solution processed AZO/MWCNT nanocomposite

A solution processed aluminum-doped zinc oxide (AZO)/multi-walled carbon nanotube (MWCNT) nanocomposite thin film has been developed offering simultaneously high optical transparency and low electrical resistivity, with a conductivity figure of merit (σDC/σopt) of ~75-better than PEDOT:PSS and many graphene derivatives. The reduction in sheet resistance of thin films of pristine MWCNTs is attributed to an increase in the conduction pathways within the sol-gel derived AZO matrix and reduced inter-MWCNT contact resistance. Films have been extensively characterized by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), transmission electron microscopy (TEM), X-ray diffractometry (XRD), photoluminescence (PL), and ultraviolet-visible (UV-vis) spectroscopy. © 2013 Elsevier Ltd and Techna Group S.r.l. All rights reserved.

Stakeholder engagement in early stage product-service system development for healthcare informatics

This paper presents the findings from four case studies on stakeholder engagement in new health information and communication technology (ICT) product-service system (PSS) development. The degree of connectivity between the new health ICT PSS and its intended operating environment has emerged to be an important contextual factor that may impact the decision of stakeholder engagement in the early stage development process. Along with the proposition of a four-level framework to guide stakeholder identification for new PSS development, three stakeholder engagement propositions that are based on the degree of connectivity are developed. Analysis has shown that there can be two types of connectivity: data and process. Moreover, each connectivity type can be characterized by how much the new PSS is connected with its environment: independent if there is no linkage, linked if it interfaces with, or incorporated if it is embedded into. Furthermore, depending upon whether and to what extent the PSS has data and process connectivity with its intended operating environment, the stakeholder engagement needs in early stage development vary. The propositions presented in this paper provide important directions for future work exploring PSS characterization and stakeholder engagement decision in early stage new PSS development in the healthcare industry. © 2013 PICMET.

Bioelectronics meets nanomedicine for cardiovascular implants: PEDOT-based nanocoatings for tissue regeneration.

BACKGROUND: An exciting direction in nanomedicine would be to analyze how living cells respond to conducting polymers. Their application for tissue regeneration may advance the performance of drug eluting stents by addressing the delayed stent re-endothelialization and late stent thrombosis. METHODS: The suitability of poly (3, 4-ethylenedioxythiophene) (PEDOT) thin films for stents to promote cell adhesion and proliferation is tested in correlation with doping and physicochemical properties. PEDOT doped either with poly (styrenesulfonate) (PSS) or tosylate anion (TOS) was used for films' fabrication by spin coating and vapor phase polymerization respectively. PEGylation of PEDOT: TOS for reduced immunogenicity and biofunctionalization of PEDOT: PSS with RGD peptides for induced cell proliferation was further applied. Atomic Force Microscopy and Spectroscopic Ellipsometry were implemented for nanotopographical, structural, optical and conductivity measurements in parallel with wettability and protein adsorption studies. Direct and extract testing of cell viability and proliferation of L929 fibroblasts on PEDOT samples by MTT assay in line with SEM studies follow. RESULTS: All PEDOT thin films are cytocompatible and promote human serum albumin adsorption. PEDOT:TOS films were found superior regarding cell adhesion as compared to controls. Their nanotopography and hydrophilicity are significant factors that influence cytocompatibility. PEGylation of PEDOT:TOS increases their conductivity and hydrophilicity with similar results on cell viability with bare PEDOT:TOS. The biofunctionalized PEDOT:PSS thin films show enhanced cell proliferation. CONCLUSIONS: The application of PEDOT polymers has evolved as a new perspective to advance stents. GENERAL SIGNIFICANCE: In this work, nanomedicine involving nanotools and novel nanomaterials merges with bioelectronics to stimulate tissue regeneration for cardiovascular implants. This article is part of a Special Issue entitled Organic Bioelectronics - Novel Applications in Biomedicine.