Spelling suggestions: "subject:"prolonged"" "subject:"aprolonged""
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Exploring New Work Options for Emergency DispatchersCage, Kailyn January 2013 (has links)
No description available.
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Strategies for Enhancing Customer Retention in Long Lead Time Industries : Managing and Sustaining Long-Term B2B RelationshipsLindström, Joakim, Blom, David January 2024 (has links)
In the dynamic landscape of global commerce, the business-to-business (B2B) sector stands out for its significance and changing nature. Traditional values used to evaluate a supplier, such as price and quality, are becoming accompanied by "soft" values, such as cultural and social fit. This change makes the B2B market more intricate and illuminates a fundamental change in how businesses and customers evaluate their relationships. Another factor straining the relationship between companies and customers is prolonged lead times, i.e., when the lead time is longer than usual. Prolonged lead times are an imperative problem for markets and companies, heavily affecting customer retention and relationships, and can result in a loss of business and monetary punishments. Given the changes in how businesses and customers evaluate B2B relationships and the effects of prolonged lead times, companies must evaluate and develop existing customer retention strategies to meet the changing demands. Thus, this thesis explores how B2B companies with long lead times can manage and develop their customer relationships to increase customer retention and decrease customer churn in the long term. Given the comprehensive scope of the thesis, the literature review assumes a pivotal role. It provides the foundation for answering the purpose and research questions, including relationship marketing, organizational buying behavior, switching behavior, and customer success management. In addition to the literature review, 19 semi-structured interviews were conducted to collect primary data. The primary data was later analyzed through thematic analysis to assist answering the purpose and research questions. A descriptive purpose and deductive and qualitative approach characterize the thesis. The thesis reached the following conclusions concerning factors affecting the willingness to remain in a long-term B2B relationship: Delivery and track record are standard evaluation criteria for customers evaluating a supplier, heavily affecting the willingness to remain in a long-term B2B relationship. Relationship value dependence is critical in the willingness to remain in a long-term B2B relationship. Relationship development affects commitment, trust, communication, transparency, and customer satisfaction, which are critical factors. Non-task dimensions, such as the degree of innovation and values, are becoming more prevalent concerns for customers evaluating their suppliers. Value in Use monitoring and Value in Use enhancement measures, i.e., value measurements during and after a process, affect the willingness to remain in a long-term B2B relationship. Co-creation is increasingly prioritized and positively affects the willingness to remain in a long-term B2B relationship. / I globala handelns dynamiska landskap sticker B2B-marknaden ut för sin betydelse och förändrande natur. Traditionella värderingar använda för att utvärdera en leverantör, till exempel pris och kvalitet, blir numera en del av en större utvärdering, där mjuka värderingar, till exempel kulturell och social lämplighet, blir allt vanligare. Dessa förändringar gör B2B-marknaden mer invecklad och belyser den fundamentala förändringen i hur företag och kunder utvärderar sin relation. En annan faktor som påverkar förhållandet mellan företag och kunder är förlängda ledtider, det vill säga när ledtiden är längre än vanligt. Förlängda ledtider är ett signifikant problem för marknadsförare och företag som påverkar kundretention och förhållandet, samt kan medföra risken att förlora en affär eller monetära bestraffningar. Givet förändringarna i hur företag och kunder utvärderar sitt förhållande samt effekterna från förlängda ledtider måste företag utvärdera och utveckla sina befintliga kundretentionsstrategier för att möta kundernas förändrande krav. Således undersöker denna masteruppsats hur B2B-företag med förlängda ledtider kan hantera och utveckla sina kundrelationer för att öka kundretention och minska kundomsättning på lång sikt. Givet studiens omfattning ges litteraturstudien en betydande roll. Litteraturstudien är basen för besvarandet av syftet och forskningsfrågorna, och inkluderar relationsmarknadsföring, organisatoriskt köpbeteende, bytesbeteende och customer success management. Utöver litteraturstudien genomfördes 19 semi-strukturerade intervjuer för att samla in primärdata, som sedan analyserades med hjälp av tematisk analys för att underlätta besvarandet av syftet och forskningsfrågorna. Uppsatsen karaktäriseras av ett deskriptivt syfte med deduktiv och kvalitativ ansats. Studien resulterade i följande slutsatser avseende vilka faktorer som påverkar benägenheten att stanna i en långsiktigt B2B-relation: Leverans och historisk framgång är vanligt förekommande utvärderingskriterier för kunder som utvärderar en leverantör med stor påverkan på benägenheten att stanna i en långsiktigt B2B-relation. Beroendet av värdet från förhållandet är kritiskt när det kommer till benägenheten att stanna i en långsiktigt B2B-relation. Utvecklingen av relationen påverkar de kritiska faktorerna engagemang, tillit, kommunikation, transparens och kundnöjdhet. Olika roller inom köpprocessen är unika och mötesdeltagare bör anpassas. Non-task dimensioner, till exempel grad av innovation och värderingar blir alltmer vanligt förekommande kriterier när kunder utvärderar sina leverantörer. Value in Use monitoring och Value in Use enhancement, det vill säga mätningar under och efter en process, påverkar benägenheten att stanna i en långsiktigt B2B-relation. Samskapande blir alltmer prioriterat och påverkar benägenheten att stanna i en långsiktigt B2B-relation positivt.
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Individual and Organizational Challenges to Implementing Prolonged Exposure Therapy in the Military Health System: A Systematic Review of Client and Provider PerspectivesCloutier, Paris R 01 January 2024 (has links) (PDF)
Military veterans and active-duty service members face high rates of posttraumatic stress disorder (PTSD), a chronic and debilitating condition that is comorbid with other negative psychological and social outcomes. PTSD symptomology in military careers is attributed to unique organizational factors and risks both during and post-deployment. Delivering modern, effective PTSD treatments derived from evidence-based research to the military population is a multi-faceted effort. Among these interventions, prolonged exposure therapy (PE) is a safe and effective trauma-focused treatment for veterans. To yield higher rates of PE success, common challenges faced by both military clients and their clinicians that may be impairing adoption were examined in this systematic review of 136 articles. While military clients face challenges related to treatment access and retention, clinicians entrusted to administer PTSD treatment report limited training and skepticism towards PE as barriers. When these complex barriers converge, PE, while shown successful at reducing PTSD symptomology in randomized controlled trials, may fail to achieve positive outcomes. To aid current understanding of this multi-level issue, a systematic review of existing client and clinician studies was conducted to synthesize common problems and facilitators to PE implementation. Findings suggest that low treatment readiness, complex symptom presentations, and time conflicts remain significant barriers. Providers could benefit from increased organizational support and training while clients experience better treatment retention and outcomes when a strong therapeutic alliance and social support is present.
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Forced intimacy : the experiences of sexually victimized prisonersPrince, Craig 11 1900 (has links)
Total institutions' (which include prisons) unique context
prescribes "confinement" of inmates. Coping mechanisms applied
"outside" (especially the ability to create distance from
stressful events) is thus ineffective.
Another common feature is lack of privacy, which may result
in "forced intimacy" - individuals being forced into a situation
of physical and psychological "invasion" (beyond the norm) of
their person/personal space. Victims lose control over intimate
decisions, including who may and may not be intimate with them.
Within prisons, gangs "force intimacy" by sexually
victimizing inmates, taking advantage of the context to heighten
their power, and to control inmates "under" them. Four
(subjects) victims' experiences and means of adaptation/
empowerment were investigated phenomenologically.
Results indicated that inadequately empowered victims
suffer prolonged and repeated victimization - a continued "posttraumatic
stress disorder" - which is more traumatizing and
draining than one circumscribed traumatic event (due to its
intensity, immobilization and resulting drastic change of
"personality"). / Psychology / M.A. (Clinical Psychology)
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Diapause by seed predators and parasitoids in Chionochloa mast seeding communitiesSarfati, Michal January 2008 (has links)
Chionochloa, a genus of snow tussock grasses native to New Zealand, exhibits pronounced mast seeding. Chionochloa suffers very high levels of pre-dispersal flower and seed predation by three main insects: Eucalyptodiplosis chionochloae, a cecidomyiid midge, which is formally described here; Megacraspedus calamogonus, a gelechiid moth and Diplotoxa similis, a chloropid fly.
Seven species of parasitoids that attack these seed predators were discovered. Four species parasitize M. calamogonus (one tachinid fly and three hymenopteran wasps), one parasitizes D. similis (Hymenoptera: Eulophidae) and two parasitize E. chionochloae, (a pteromalid wasp Gastrancistrus sp. and a platygastrid wasp Zelostemma chionochloae, which is given a formal description here).
The abundance, predation levels by each of the insect species, and interactions between all the organisms in the community were studied across three elevations at Mount Hutt over three summer seasons. M. calamogonus was most abundant at 450 m altitude during all three seasons. D. similis was most common at 1070 m altitude, while its predation levels peaked in low flowering seasons and decreased in high seasons. E. chionochloae was abundant in all three altitudes and increased its predation levels with increasing flowering intensity. E. chionochloae was confirmed to use prolonged diapause of at least three years. Prolonged diapause was also confirmed in its two parasitoids.
Chionochloa plants were manipulated with various treatments to test the effect on diapause in E. chionochloae and its two parasitoids. Treatments included plant warming, root pruning, gibberellic acid sprayed on the plants and combinations of these treatments. All three insects changed their emergence in response to some treatments and therefore it was suggested that combined with risk-spreading diapause, they may use some predicting to emerge from prolonged diapause. E. chionochloae control their diapause following some of the cues that Chionochloa use for flowering, while Z. chionochloae and Gastrancistrus in some cases follow their host’s cues and in others use similar cues as Chionochloa plants. Emergence or diapause predictions differed across elevations and plant species in all three insect seed/flower predators.
E. chionochloae had female-biased sex ratios in different populations even after prolonged diapause. There was week evidence that both parasitoid species are female-biased in the first emergence year and male-biased after more than one year in diapause. Therefore it was suggested that diapause is not more costly for females of E. chionochloae and its parasitoid than for males. Females of all three species were not found to be better predictors (i.e, more likely to respond to treatments by not entering extended diapause) than males.
The complex interactions of all the organisms in this web are thought to be sensitive to climate, and it was suggested that the global climate change may alter this sensitive system.
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Diapause by seed predators and parasitoids in Chionochloa mast seeding communitiesSarfati, Michal January 2008 (has links)
Chionochloa, a genus of snow tussock grasses native to New Zealand, exhibits pronounced mast seeding. Chionochloa suffers very high levels of pre-dispersal flower and seed predation by three main insects: Eucalyptodiplosis chionochloae, a cecidomyiid midge, which is formally described here; Megacraspedus calamogonus, a gelechiid moth and Diplotoxa similis, a chloropid fly. Seven species of parasitoids that attack these seed predators were discovered. Four species parasitize M. calamogonus (one tachinid fly and three hymenopteran wasps), one parasitizes D. similis (Hymenoptera: Eulophidae) and two parasitize E. chionochloae, (a pteromalid wasp Gastrancistrus sp. and a platygastrid wasp Zelostemma chionochloae, which is given a formal description here). The abundance, predation levels by each of the insect species, and interactions between all the organisms in the community were studied across three elevations at Mount Hutt over three summer seasons. M. calamogonus was most abundant at 450 m altitude during all three seasons. D. similis was most common at 1070 m altitude, while its predation levels peaked in low flowering seasons and decreased in high seasons. E. chionochloae was abundant in all three altitudes and increased its predation levels with increasing flowering intensity. E. chionochloae was confirmed to use prolonged diapause of at least three years. Prolonged diapause was also confirmed in its two parasitoids. Chionochloa plants were manipulated with various treatments to test the effect on diapause in E. chionochloae and its two parasitoids. Treatments included plant warming, root pruning, gibberellic acid sprayed on the plants and combinations of these treatments. All three insects changed their emergence in response to some treatments and therefore it was suggested that combined with risk-spreading diapause, they may use some predicting to emerge from prolonged diapause. E. chionochloae control their diapause following some of the cues that Chionochloa use for flowering, while Z. chionochloae and Gastrancistrus in some cases follow their host’s cues and in others use similar cues as Chionochloa plants. Emergence or diapause predictions differed across elevations and plant species in all three insect seed/flower predators. E. chionochloae had female-biased sex ratios in different populations even after prolonged diapause. There was week evidence that both parasitoid species are female-biased in the first emergence year and male-biased after more than one year in diapause. Therefore it was suggested that diapause is not more costly for females of E. chionochloae and its parasitoid than for males. Females of all three species were not found to be better predictors (i.e, more likely to respond to treatments by not entering extended diapause) than males. The complex interactions of all the organisms in this web are thought to be sensitive to climate, and it was suggested that the global climate change may alter this sensitive system.
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Forced intimacy : the experiences of sexually victimized prisonersPrince, Craig 11 1900 (has links)
Total institutions' (which include prisons) unique context
prescribes "confinement" of inmates. Coping mechanisms applied
"outside" (especially the ability to create distance from
stressful events) is thus ineffective.
Another common feature is lack of privacy, which may result
in "forced intimacy" - individuals being forced into a situation
of physical and psychological "invasion" (beyond the norm) of
their person/personal space. Victims lose control over intimate
decisions, including who may and may not be intimate with them.
Within prisons, gangs "force intimacy" by sexually
victimizing inmates, taking advantage of the context to heighten
their power, and to control inmates "under" them. Four
(subjects) victims' experiences and means of adaptation/
empowerment were investigated phenomenologically.
Results indicated that inadequately empowered victims
suffer prolonged and repeated victimization - a continued "posttraumatic
stress disorder" - which is more traumatizing and
draining than one circumscribed traumatic event (due to its
intensity, immobilization and resulting drastic change of
"personality"). / Psychology / M.A. (Clinical Psychology)
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The impact of exposure to constant light and hyperoxia on the retina / L'impacte de l'exposition à une lumière constante et l'hyperoxie sur la rétineMehdi, Madah Khawn -i- Muhammad 04 April 2013 (has links)
Les yeux forment des avant-postes visuels importants du cerveau. Comme les autres organes, la rétine sensorielle des yeux est vulnérable aux effets nocifs des facteurs environnementaux, tels que la lumière et l'oxygène. Dans ce travail, nous nous sommes concentrés sur l’impact de l’exposition à une lumière constante et l’hyperoxie prolongée sur l'architecture et la fonction rétinienne. Dans la première partie de notre étude, nous avons montré qu’ une exposition de sept jours à une lumière constante perturbe la phagocytose des bâtonnets et cônes et régule négativement leur renouvellement dans la « rétine riche en cônes " d’Arvicanthis ansorgei. Notre étude donne un aperçu sur la physiopathologie des cônes, ce qui représente la principale source de handicap visuel dans une variété de pathologies rétiniennes, y compris la rétinite pigmentaire (RP) et la dégénérescence maculaire liée à l'âge (DMLA). Dans la deuxième partie de notre étude, nous avons montré qu’ une exposition de cinq jours à l’hyperoxie entraîne chez les souris néonatales une perte significative de cellules ganglionnaires dans les régions périphériques de la rétine, et de cellules à mélanopsine (ipRGC). L’exposition prolongée à l’hyperoxie perturbe également la capacité de photoentrainment des animaux probablement due à la perte des ipRGC et la perte de la rhodopsine dans les segments externes des bâtonnets chez les animaux traités. / Eyes form important visual outposts of the brain. Just like other organs, sensory retina in the eyes is also vulnerable to the injurious effects of environmental factors; such as light and oxygen. In this work, we have focused on the impacts of constant prolonged light and hyperoxia on the retinal architecture and function. In the first part of our study, we show that seven days of constant light disrupts rod and cone phagocytosis and downregulates their turnover in the “cone rich retina” of Arvicanthis ansorgei. The study gives an insight on the cone pathophysiology, which represents the major source of visual handicap in a variety of retinal pathologies, including retinitis pigmentosa (RP) and age-related macular degeneration (AMD). In the second part of our study, we show that five days of hyperoxia treatment in the neonatal mice results in the significant loss of retinal ganglion cells in the peripheral regions; the loss of melanopsin expressing retinal ganglion cells (ipRGC) was found to be significant. Hyperoxia also affects the photoentrainment capability of the animals probably because of the loss of ipRGC and the loss of rhodopsin in the outer segments of the photoreceptors in the treated animals.
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Evaluation in vitro et in vivo d’un polymère biorésorbable à la Gentamycine dans le traitement expérimental d’infections ostéo-articulaires / In vitro and in vivo evaluation of a gentamicin-loaded bioresorbable polymer in the experimental treatment of osteoarticular infectionsMarcheix, Pierre-Sylvain 21 December 2016 (has links)
Le traitement d'une infection ostéo-articulaire nécessite une prise en charge longue, obligeant à des chirurgies itératives et à un traitement antibiotique systémique prolongé. À ce jour, le polyméthacrylate de méthyle est le vecteur d’antibiotique local le plus fréquemment utilisé chez l’homme pour traiter une infection ostéo-articulaire. Cependant les PMMA sont non résorbables et obligent à multiplier les interventions chirurgicales afin d’aboutir au traitement définitif de l’infection ostéo-articulaire. Le PMMA ne permet pas une libération complète de l’antibiotique avec de surcroît des doses inférieures à la CMI du germe en cause, pouvant faciliter l’émergence de bactéries résistantes. L'objectif de notre travail était d’obtenir une libération locale efficace et prolongée d’antibiotique grâce à un polymère entièrement résorbable. Le cahier des charges établi pour l’élaboration de ce polymère était le suivant : système matriciel offrant une libération de gentamicine à une dose de 1 à 2 mg/jour/g de mélange sur une période de plus de 10 jours. De plus, le polymère devait être bio-résorbable, c’est-à-dire qu’il devait pouvoir être dégradé jusqu'à obtenir des fragments pouvant être éliminés naturellement par l'organisme. Afin de répondre à ces exigences, il a été créé le PLA50P, Poly(D,L-acide lactique) de haut poids moléculaire. Afin d’obtenir le mélange gentamycine-PLA, une technique de compression des poudres des deux composants a été mise en œuvre. Ce polymère pouvait être stérilisé par -irradiation, sans influence sur les caractéristiques de relargage du polymère.La cinétique in vitro de la gentamicine relarguée par le PLA50GS montrait un pic maximum de gentamicine libérée obtenu à 12 jours et une stabilisation ensuite jusqu’à 63 jours de la quantité relarguée. La quantité cumulée de gentamicine relarguée à 3 semaines in vitro est de 54 % de la quantité contenue initialement dans PLA50GS. In vivo, nous observions une libération in situ de 5,1 µg/mL de gentamicine à J3, de 1,9 µg/mL de gentamicine à J7 et de 0 µg/mL à 5 semaines avec disparition de PLA50GS à l’examen macroscopique. Nous avons ainsi pu mettre en évidence, in vitro et in vivo, un relargage de la gentamicine à des doses supérieures à la CMI du germe et ce pendant plus de trois semaines.Afin de confirmer ces observations, nous avons ensuite mis au point un modèle d’infection périostée chez le rat. Pour ce faire nous avons utilisé des rats âgés de 10 à 12 semaines avec une injection au contact de l’os et au 1/3 moyen de la patte arrière de deux fois 100 ml de SAMS d’origine animale. L’utilisation du PLA50GS a montré sa supériorité par rapport à une administration parentérale d’une dose équivalente de Gentamicine avec une négativation du contage bactériologique chez tous les rats traités par le polymère chargé à la Gentamicine. Nous avons ensuite voulu traiter une infection articulaire grâce à notre polymère. Nous avons donc créé un modèle animal utilisant un lapin femelle de 4 kg avec une injection de 1 ml d’une solution à 103 CFU/ml de staphylococcus méthi-sensible d’origine léporidée. Le PLA50GS nous a permis de réduire très significativement la charge bactérienne intra-articulaire (baisse de 3 à 4 log10 soit 1000 à 10000 fois moins de bactéries) alors que le traitement antibiotique par voie générale dit de référence ne nous a pas permis de réduire l’infection intra-articulaire de façon significative par rapport au groupe non traité. Le PLA50GS nous a ainsi permis de réduire l’infection de 3 log10 par rapport aux autres groupes avec 2 lapins sur 6 guéris de leur infection.Le PLA50GS présente, ainsi, les caractéristiques suivantes : (i) stabilité de la Gentamicine au sein du polymère, (ii) polymère sous forme de poudre stable, (iii) relargage prolongé de la Gentamicine pendant plusieurs semaines, (iv) effet « burst » présent mais limité, (v) très bonne biotolérance, et (vi) efficacité supérieure aux traitements antimicrobiens classiques. / The treatment of soft-tissue infections, osteomyelitis, and acute or chronic septic arthritis is a lengthy process that involves repeated surgical procedures and the systemic administration of antibiotics for at least 6 weeks to 3 months. Poor diffusion of antibiotics into bones and joints requires high doses given parenterally for long periods. At present, the antibiotic vector most widely used in humans with bone or joint infections is polymethylmethacrylate. Because PMMA is not bioabsorbable, multiple surgical procedures are required to eradicate infection. Furthermore, PMMA does not release its full antibiotic load over time and may yield local antibiotic concentrations lower than the minimal inhibitory concentration of the causative organism, thereby promoting the emergence of resistant strains. The objective of our work was to develop a fully bioabsorbable polymer capable of ensuring the prolonged and efficient release of its antibiotic load, thus improving the management of bone and joint infections. The specifications for the polymer included the release by the matrix system of 1-2 mg of gentamicin per day and per gram of mixture over more than 10 days. Other specifications were appropriate physical characteristics, a drug release rate sufficient to ensure optimal treatment safety, and ease of implantation. The polymer was also to be bioabsorbable, i.e., subject to degradation into fragments capable of being eliminated naturally by the body. High-molecular weight PLA50P, Poly(D,L-lactic acid) was created and found to meet these specifications. Use of this polymer as large particles (0.5 to 1 mm) limited the initial burst phenomenon. A gentamicin-PLA50P mixture was obtained by compression of the two components prepared in powder form. The antibiotic load was set at 20% to limit the initial burst. The polymer can be sterilized by gamma irradiation, which has no effect on drug release characteristics.In vitro kinetic studies of gentamicin release by the polymer showed a peak on day 12 followed by a plateau that lasted until day 63. After 3 weeks, the cumulative amount of gentamicin released in vitro was 54% of the total amount loaded onto the polymer. In vivo gentamicin concentrations measured in situ were 5.1 µg/mL on day 3, 1.9 µg/mL on day 7, and 0 µg/mL on day 35, when the polymer was no longer visible to the naked eye. Thus, both in vivo and in vitro, gentamicin was released in concentrations greater than the MIC of the microorganism, for longer than 3 weeks.To test the gentamicin-loaded polymer, we created a rat model of periosteal infection. Rats aged 10-12 weeks received two 100 mL injections of methicillin-susceptible Staphylococcus aureus collected from animals, into the middle third of the hind leg, in contact with the bone. Treatment with gentamicin-loaded PLA50P proved superior over parenteral administration of an equivalent gentamicin dose, consistently reverting the bacteriological cultures to negative. We then created a rabbit model of septic arthritis. A doe weighing 4 kg received an add intraarticular injection of 1 mL of a solution containing 103 cfu/mL of a methicillin-sensitive S. aureus strain collected from another rabbit. Gentamicin-loaded PLA50P treatment induced a highly significant drop in the intraarticular bacterial load (by 3-4 log10), whereas standard systemic gentamicin therapy failed to significantly diminish bacterial counts comparatively to the untreated controls. Thus, gentamicin-loaded PLA50P diminished the bacterial load by 3 log10 comparatively to the other groups and allowed eradication of the infection in 2 of the 6 rabbits.In sum, gentamicin-loaded PLA50P (i) ensures the stability of the antibiotic; (ii) is available as a stable powder; (iii) ensures the prolonged release of gentamicin over several weeks; (iv) produces a limited burst effect; (v) exhibits very good biotolerance; (vi) and is more effective than standard antimicrobial therapy.
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Efficiency and stability studies for organic bulk heterojunction solar cellsAugustine, B. (Bobins) 29 November 2016 (has links)
Abstract
The qualitative and quantitative characteristics of each component layer constituting the structure of organic bulk heterojunction solar cells (OSC-BHJ) contribute significantly towards its overall performance. One of the prevalent issues resulting in reduced device efficiency is due to the conformational inhomogeneities in the active and buffer layers. The mechanical stress, extended thermal exposure and presence of mutually reactive component layers etc., affects negatively on the device stability. Effective methods to address these issues will be extensively benefited by the industry since the current commercialisation of the technology is hindered owing to the lower efficiency and stability of these devices.
This dissertation focuses on methods to coherently enhance the performance and longevity of the OSC-BHJ devices. The efficiency enhancements of the devices in this work were achieved through two main routes. The first route was through morphological improvement of the active layer. The second route was through boosting the electrical characteristics of hole transporting conducting polymer layer (HTL) by controlled annealing conditions. The introduction of a suitable additive in the active layer was found to reduce unfavourable phase segregation thus resulting in enhanced morphology. Further, the annealing conditions in different atmospheres (air, nitrogen and vacuum) were found to have a clear influence on the optimum functioning of the HTL in the device. Regarding the stability improvement study done in this work, a method of employing suitable interlayer was developed to effectively abate the internal degradation occurring in the device due to etching reaction on the indium tin oxide (ITO) anode by the HTL. Moreover, experimental investigations were carried out for drawing fundamental understanding of stability degenerating issues such as the influence of mechanical defects on transparent conducting metal oxide (ITO) anode on the performance of the device and heat induced degradations in the low band gap polymer-fullerene active layer.
The highlight of this research is that the discovered methods are inexpensive, efficient, and easy to adopt. The results of the study could help the technology to overcome some of its limitations and accelerate its progress towards commercialisation. / Tiivistelmä
Orgaanisten heteroliitosaurinkokennojen kerrosrakenteen ominaisuudet ja laatu vaikuttavat merkittävästi aurinkokennojen toiminnallisuuteen. Erityisesti rakenteelliset epähomogeenisuudet aktiivi- ja puskurikerroksissa heikentävät kennon hyötysuhdetta. Kennojen stabiilisuutta tarkasteltaessa myös mekaanisella rasituksella, pitkittyneellä lämpöaltistuksella ja materiaalien reagoinneilla keskenään kerrosten välillä, on selkeä negatiivinen vaikutus kennojen stabiilisuuteen. Orgaanisen aurinkokennoteknologian kaupallistamisen rajoitteina ovat kennojen heikko hyötysuhde ja stabiilisuus, joten menetelmät jotka tarjoavat ratkaisuja edellä mainittuihin ongelmiin, ovat erittäin tärkeitä teknologiaa kaupallistavalle teollisuudelle.
Tämä väitöskirja keskittyy johdonmukaisesti selvittämään tapoja, joilla voidaan parantaa heteroliitosaurinkokennojen hyötysuhdetta ja elinikää. Hyötysuhteen tehostamiseksi valittiin kaksi eri lähestymistapaa, joista ensimmäisessä keskityttiin aktiivikerroksen morfologian parantamiseen ja toisessa aukkoja kuljettavan kerroksen sähköisten ominaisuuksien parantamiseen lämpökäsittelyprosessin avulla. Sopivan lisäaineen avulla aktiivikerroksen ei-toivottua kiteytymistä voidaan pienentää ja parantaa näin kerroksen morfologiaa. Lisäksi työssä todettiin, että lämpökäsittelyn aikaisella ympäristöolosuhteella (ilma, typpi, tyhjiö) on merkittävä vaikutus puskurikerroksen optimaaliseen toimintaan aurinkokennossa. Stabiilisuuden parantamiseksi kehitettiin välikerroksen hyödyntämiseen perustuva menetelmä, jolla voidaan tehokkaasti vähentää kennojen sisäisessä rakenteessa tapahtuvaa toiminnallisuuden heikkenemistä, joka aiheutuu aukkoja kuljettavan kerroksen syövyttävästä vaikutuksesta indiumtinaoksidi (ITO) pohjaiseen anodiin. Tämän lisäksi työssä tutkittiin kokeellisesti stabiilisuuteen heikentävästi vaikuttavia tekijöitä, kuten mekaanisen rasituksen aiheuttamia vaurioita metallioksidi (ITO) anodissa ja lämpöaltistuksesta aiheutuvia vikoja polymeeri-fullereeni rakenteeseen perustuvassa aktiivikerroksessa.
Tutkimuksen keskeisin tulos on, että esitellyt keinot aurinkokennojen hyötysuhteen ja stabiilisuuden parantamiseen ovat edullisia, tehokkaita ja helppoja hyödyntää. Tulokset voivat merkittävästi edistää orgaanisten aurinkokennojen teknistä kehitystä ja kiihdyttää niiden tuloa kaupallisiksi tuotteiksi.
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