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Quantum-confined excitons in 2-dimensional materialsPalacios-Berraquero, Carmen January 2018 (has links)
The 2-dimensional semiconductor family of materials called transition metal dichalcogenides (2d-TMDs) offers many technological advantages: low power consumption, atomically-precise interfaces, lack of nuclear spins and ease of functional integration with other 2d materials are just a few. In this work we harness the potential of these materials as a platform for quantum devices: develop a method by which we can deterministically create single-photon emitting sites in 2d-TMDs, in large-scale arrays. These we call quantum dots (QDs): quantum confinement potentials within semiconductor materials which can trap single-excitons. The single excitons recombine radiatively to emit single-photons. Single-photon sources are a crucial requirement for many quantum information technology (QIT) applications such as quantum cryptography and quantum communication. The QDs are formed by placing the flakes over substrates nano-patterned with protru- sions which induce local strain and provoke the quantum confinement of excitons at low temperatures. This method has been successfully tested in several TMD materials, hence achieving quantum light at different wavelengths. We present one of the very few systems where quantum confinement sites have been shown to be deterministically engineered in a scalable way. Moreover, we have demonstrated how the 2d-based QDs can be embedded within 2d- heterostructures to form functional quantum devices: we have used TMD monolayers along with other 2d-materials - graphene and hexagonal boron nitride - to create quan- tum light-emitting diodes that produce electrically-driven single-photons. Again, very few single-photon sources can be triggered electrically, and this provides a great ad- vantage when considering on-chip quantum technologies. Finally, we present experimental steps towards using our architecture as quantum bits: capturing single-spins inside the QDs, using field-effect type 2d-heterostructures. We are able to controllably charge the QDs with single-electrons and single-holes – a key breakthrough towards the use of spin and valley pseudospin of confined carriers in 2d-materials as a new kind of optically addressable matter qubit. This work presents the successful marriage of 2d-semiconductor technology with QIT, paving the way for 2-dimensional materials as platforms for scalable, on-chip quantum photonics.
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Uma metodologia de otimização para sistemas de iluminação que empregam LEDs / An optimization methodology for lighting systems that employ LEDGuisso, Ronaldo Antonio 09 March 2015 (has links)
Conselho Nacional de Desenvolvimento Científico e Tecnológico / This work presents an optimization methodology for lighting systems that employ LED.
Initially, this work brings a calculation methodology capable of obtaining a thermal resistance
of heat sink from their dimensions of area, besides enable optimization of the system through
reducing their volume by through of change in the number of finned, length and consequently
the weight of heat sink. Subsequently, the thesis present a new optimization methodology that
has the objective of find the optimal point of operation lighting system taking into consideration
the parameters of application current in the device, luminous flux, junction temperature, thermal
resistance heat sink, number of LED and lifetime. An example of project is shown, confirming
the theory, where the obtained results through of routine calculation coincided with the values
found in experimental. The work also present the development of electronic topologies to power
a public lighting system employing LED. Therefore, a driver to power of LED based in the
integrated two-flyback converters was proposed. One prototype this system was implemented,
where the luminaire provide a power of 63W. The experimental results proved the project
methodology through of system satisfactory operation, presenting power factor near unit, high
efficiency and a low input current distortion was obtained. / Este trabalho apresenta uma metodologia de otimização para sistemas de iluminação
que empregam LEDs. Inicialmente, traz-se uma metodologia de cálculos capaz de obter a
resistência térmica de dissipadores de calor a partir de suas dimensões de área, além de
possibilitar a otimização do sistema através da redução do volume do mesmo por meio da
variação do número de aletas, do comprimento e consequentemente da massa do dissipador.
Posteriormente o trabalho apresenta uma nova metodologia de otimização que tem o objetivo
de encontrar o ponto ótimo de operação do sistema de iluminação, levando-se em conta os
parâmetros de corrente direta aplicada no dispositivo, fluxo luminoso, temperatura de junção,
resistência térmica do dissipador, número de LEDs e vida útil dos mesmos. Um exemplo de
projeto é demonstrado confirmando a teoria apresentada, onde os resultados obtidos através da
rotina de cálculos coincidiram com os valores encontrados experimentalmente. O trabalho
também apresenta o desenvolvimento de uma topologia eletrônica para alimentar um sistema
de iluminação pública empregando LEDs. Dessa maneira, um driver para acionamento de LEDs
baseado na integração de dois conversores flyback foi proposto. Um protótipo desse sistema foi
implementado, onde a luminária apresenta uma potência de 63W. Resultados experimentais
comprovam a metodologia de projeto através da operação satisfatória do sistema, apresentando
fator de potência próximo ao unitário, elevada eficiência e o conteúdo harmônico da corrente
de entrada do sistema de iluminação atendeu a norma.
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Efeitos da terapia LED (Light-Emitting Diode) de baixa potência sobre o desempenho funcional de jovens atletas de futebolMaldonado, Thiago 22 March 2013 (has links)
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Previous issue date: 2013-03-22 / Context and Objectives: Nowadays, phototherapy has been used to enhance physical performance and to accelerate recovery after exercise. The aim of this study was to evaluate the effects of LED therapy (850 nm) and low power (50 mW) on the physical performance of soccer players after 6 weeks of soccer training. Study design/materials and methods: a randomized, double-blind clinical trial, controlled with placebo study was conducted. Sixteen soccer athletes aged between 14 and 16 years participated in the study. The athletes were randomly allocated into 2 groups: (i) training group associated with the LED therapy (LEDT) and (ii) training group associated with the placebo LED therapy (placebo). LED therapy or placebo were applied on the quadriceps, hamstrings and sural triceps immediately after training, twice a week during 6 consecutive weeks (12 sessions of therapies). The LED device (850nm, 50 mW, 30 s on each muscle group and energy of 75 J) was used for phototherapy. The functional performance was evaluated through the jump platform (vertical jump) and photocells (10 and 35 meter races) in the period pre and post training plus LED therapy or placebo therapy. Results: the LEDT Group significantly increased the height (cm) of vertical jump (from 36.02±3.95 to 39.20±4.52; p<0.001) and the muscle power (W) (from 382.62±31.82 to 417.62±31.19; p=0.003) in this same test. The LEDT showed significant increases for the average speed (m/s) at 10 m race (from 5.94 ± 0.35 to 6.13 ± 0.45; p<0.001) and 35 m (from 7,43 ± 0,32 to 7.51 ± 0.32; p=0.003). The Placebo group showed significant increases only for the height of vertical jump (from 36.25±4.55 to 37.38±4.26; p=0.017). Conclusion: LED therapy applied after physical training can improve functional performance of soccer players, evidenced by improvements of the jump height, muscle power and speed racing. / Contexto e Objetivos: Recentemente, a fototerapia por laser e LEDs de baixa potência vem sendo utilizada para aumentar o desempenho físico e acelerar a recuperação pós-exercício. Este estudo consiste em investigar os efeitos da terapia LED, na faixa do infravermelho (850 nm) e baixa potência (50 mW) sobre o desempenho físico de atletas de futebol após 06 semanas de treinamentos específicos desse esporte. Desenho do estudo/Materiais e métodos: Foi realizado um estudo clínico, randomizado, duplo cego e com placebo. Participaram do estudo 16 atletas de futebol com idade entre 14 e 16 anos de idade. Os atletas foram alocados randomicamente em 2 grupos iguais: (i) grupo treinamento associado à terapia LED (LEDT) e (ii) grupo treinamento associado à terapia LED placebo (Placebo). A terapia LED ou placebo foi aplicada sobre o quadríceps femoral, isquiotibiais e triceps sural imediatamente após os treinamentos, 2 vezes por semana, durante 6 semanas consecutivas, totalizando 12 sessões de terapia. Foi utilizado um dispositivo contendo um arranjo de 50 LEDs de baixa potência (850nm, 50 mW, 30 s sobre cada grupo muscular e energia de 75 J). O desempenho funcional doa atletas em salto vertical e em corridas de 10 e 35 metros foram realizados através da plataforma de salto e fotocélulas no período pré e pós-treinamento e terapia LED. Resultados: O grupo LEDT aumentou significativamente a altura (cm) do salto vertical (de 36,02±3,95 para 39,20±4,52; p<0,001) e a potência muscular (W) (de 382,62±31,82 para 417,62±31,19; p=0,003) nesse mesmo teste. A velocidade média (m/s) da corrida de 10m aumentou significativamente no grupo LEDT (de 5,94±0,35 para 6,13±0,45; p<0,001) assim como para a corrida de 35m (de 7,43±0,32 para 7,51±0,32; p=0,003). O grupo Placebo mostrou aumento significativo apenas para a altura do salto vertical (de 36,25±4,55 para 37,38±4,26; p=0,017). Conclusão: A fototerapia por LED de baixa potência aplicada após o treinamento físico pode aumentar o desempenho físico dos atletas de futebol, evidenciado pelo aumento da altura de salto, potencia muscular e velocidade de corrida.
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Efeito fotobiomodulador da terapia com diodo emissor de luz de baixa intensidade na inflamação muscular induzida por exercício em ratos / Photobiomodulator effect of light emitting diode therapy on post-exercise muscular inflammation in ratsVasconcelos, Alan Bruno Silva 22 February 2017 (has links)
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / INTRODUCTION - The biological effects of low intensity light sources, such as light emitting diode therapy (LEDT), indicate that phototherapy is a method for obtaining ergogenic and recuperative effects of skeletal muscle. However, clinical trials and experimental researches differ in respect to the parameters to be used. OBJECTIVE - To compare different doses of the LED (630 nm) in the inflammation of striated skeletal muscle induced by exercise in rats. METHODS - Wistar rats were divided in five experimental groups (n=8/group): control (CON), the animals were not submitted to exercise protocol; passive recovery (RP), the animals received no treatment after induction of inflammation; LEDT (1.2 J, 4.2 J or 10.0 J), the animals were submitted to phototherapy after induction of inflammation. Skeletal muscle inflammation was induced by a protocol of 100 minutes of swimming. After exercise, the animals in the LEDT groups were exposed to phototherapy at the doses of 1.2 J, 4.2 J or 10.0 J on the triceps sural muscles (gastrocnemius and soleus). For evaluation of mechanical hyperalgesia by electronic von Frey, the animals were submitted to evaluation before and at 24 hours after swimming procedure. After 24 hours of swimming, blood samples were collected to measure creatine kinase (CK) activity. The soleus muscle was removed for histological analysis. Data were expressed as mean ± standard error of mean (S.E.M). Analysis of variance was used followed by Tukey post hoc. The histological data were performed with chi-square analysis followed by correction of Yates. This study was approved by the Ethics Committee on Research with Animals (Federal University of Sergipe) under n°. 15/2013 and by the Ethics Committe in the Use of Animals (State University of Londrina) under nº 124/2014. RESULTS - The plasma activity of CK was increased (p <0.0001) in the PR group (2071 ± 346 U / L) when compared to the CON group (683 ± 103 U / L) and attenuation (p <0.0001) of this response was observed in the LEDT (630 nm)-treated groups at the doses of 1.2 J (379 ± 71 U / L), 4.2 J (599 ± 131 U / L) or 10.0 J (544 ± 86 U / L). Regarding mechanical hyperalgesia, the PR group presented a reduction (p <0.005) in the paw withdrawal threshold (-11.9 ± 1.9 g) when compared to the CON group (2.2 ± 1.5 g). Only LEDT 4.2 J (-3.3 ± 2.4 g) altered this threshold (p <0.05) when compared to the PR group. In the histological analysis, leukocyte infiltration was observed in the muscle of animals from the PR group, in addition to areas of edema and necrosis. However, lower infiltration was observed in the animals treated with doses of 4.2 and 10.0 J. CONCLUSION: The application of LEDT (630 nm) reduces the inflammatory lesion in muscle fibers of rats submitted to exercise. The dose of 4.2 J induced better anti-inflammatory and antinociceptive effects than doses of 1.2 and 10.0 J. / INTRODUÇÃO - Os efeitos biológicos de fontes de luz de baixa intensidade, como a terapia com diodo emissor de luz (LEDT), indicam que a fototerapia induz efeitos ergogênicos e recuperativos do músculo esquelético. No entanto, ensaios clínicos e pesquisas experimentais apresentam divergências no que diz respeito aos parâmetros a serem utilizados. OBJETIVO - Comparar o efeito de diferentes doses da LEDT (630 nm) na inflamação do músculo estriado esquelético induzida por exercício em ratos. MÉTODOS - Ratos Wistar foram divididos em cinco grupos experimentais (n=8/grupo): controle (CON), animais não submetidos ao protocolo de exercício; recuperação passiva (RP), animais que não receberam tratamento após a indução da inflamação; LEDT (1,2 J; 4,2 J ou 10,0 J), animais tratados com fototerapia após indução da inflamação. A inflamação muscular esquelética foi induzida por protocolo de 100 minutos de nado. Após o exercício, os animais dos grupos LEDT foram expostos à fototerapia nas doses de 1,2 J, 4,2 J ou 10,0 J sobre os músculos tríceps sural (gastrocnêmios e sóleo). Para avaliação da hiperalgesia mecânica com o von Frey eletrônico, os animais foram submetidos a avaliação antes e 24 horas após o procedimento de nado. Após 24 horas do nado, amostras sanguíneas foram coletadas para análise da atividade de creatina quinase (CK). O músculo sóleo foi retirado para análise histológica. Os dados foram expressos como média± erro padrão da média (EPM). Foi utilizado análise de variância seguido pelo Tukey post hoc. Para os dados histológicos foi realizada análise com Qui-quadrado seguido de correção de Yates. O estudo foi aprovado pelo Comitê de Ética em Pesquisa com Animais (Universidade Federal de Sergipe) sob nº 15/2013 e pelo Comitê de Ética em Uso de Animais (Universidade Estadual de Londrina) sob nº 124/2014. RESULTADOS - No grupo RP houve um aumento (p<0,0001) da atividade plasmática de CK (2.071±346 U/L) quando comparado ao grupo CON (683±103 U/L) e houve atenuação (p<0,0001) da resposta nos grupos tratados com LEDT (630 nm) com doses de 1,2 J (379±71 U/L), 4,2 J (599±131 U/L) ou 10,0 J (544±86 U/L). Em relação à hiperalgesia mecânica, o grupo RP apresentou redução (p<0,05) no limiar de retirada da pata (-11,9±1,9 g) quando comparado ao grupo CON (2,2±1,5 g) e apenas o grupo LEDT 4,2 J (-3,3±2,4 g) alterou esse limiar (p<0,05) quando comparado ao grupo RP. Na análise histológica, foi observada infiltração de leucócitos no músculo do grupo RP, além de áreas edemaciadas e necrosadas. Porém, menor infiltração foi observada nos animais tratados com as doses de 4,2 e 10,0 J. CONCLUSÃO - A aplicação de LEDT (630 nm) reduz a lesão inflamatória nas fibras musculares de ratos submetidos ao exercício. A dose de 4,2 J induziu melhor efeito anti-inflamatório e antinociceptivo do que as doses de 1,2 e 10,0 J.
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Estudo das propriedades eletrônicas e ópticas de filmes e dispositivos poliméricos. / Study of electronic and optical properties of polimeric films and polimeric devices.Rodrigo Fernando Bianchi 28 January 2002 (has links)
Nesse trabalho apresentamos o estudo das propriedades ópticas e elétricas de filmes e dispositivos eletrônicos de polímeros luminescentes, poli(p-fenilenovinilenos) - PPVs, semicondutores, polianilinas - PANI, e derivados desses dois polímeros. São apresentadas todas as etapas de preparação e caracterização dos dispositivos, desde as rotas de síntese dos polímeros, até a modelagem de dispositivos eletroluminescentes e de transistores de efeito de campo. Os filmes luminescentes foram caracterizados por propriedades de absorção e emissão ópticas, e função pseudo-dielétrica, mostrando dependência com a presença de grupos laterais. Filmes de PANI, por sua vez, foram caracterizados através de medidas de condutividade complexa, e os resultados obtidos mostram-se típicos de sistemas sólidos desordenados. Para interpretá-las, foi utilizado o modelo de distribuição aleatória de barreiras de energia livre (random free energy barrier model - RFEB) aplicado como ajuste aos resultados experimentais. Outra característica importante dos PPVs, estudada nessa tese, foi à degradação em condições ambientais sob iluminação. Esse efeito foi acompanhado por medidas de absorção óptica e de elipsometria, mostrando que a combinação dos efeitos do oxigênio e da luz é a principal responsável pela degradação desse material. Para explicar tal efeito, elaboramos um modelo baseado nas propriedades individuais dos cromóforos do polímero e na substituição de ligações vinílicas C=C por ligações carbonilas C=O, cuja comparação com os resultados experimentais forneceu uma estimativa para a fração degradada do polímero como função do tempo de iluminação. Foram caracterizados dispositivos emissores de luz de PPVs através de medidas corrente vs. tensão e de condutividade complexa, que através do ajuste por modelos de circuitos equivalentes e pelo modelo RFEB forneceu grandezas fundamentais como a resistividade e a constante dielétrica da camada polimérica. Finalizando, transistores de efeito de campo de poli(o-metoxianilina) - POMA (um derivado da PANI) apresentaram modulação pela tensão de porta, e um modelo baseado nas propriedades de condução da POMA levando-se em conta gradientes de mobilidade e de densidade de portadores ortogonais à superfície do polímero foi elaborado e se ajustou muito bem aos resultados experimentais. / In this thesis we report the electrical and optical characterization of polymeric thin-film and luminescent and electronic devices. The studied materials were the luminescent poly(p-phenylenevinylenes) - PPVs, semiconducting polyanilines - PANI and their derivatives. All the steps in the material preparation are described: the synthesis and the film preparation. Also, the technological details of the fabrication of the devices, light-emitting diodes (LEDs) and field-effect transistor (FETs), are presented. Luminescent films were studied by optical absorption and emission and by ellipsometry measurements, giving emphasis on the influence of lateral groups. The PANI films were electrically investigated by the analysis of the complex conductivity, whose results were adjusted by the random free energy barrier model used for disordered solids. Another important investigation was related to the photodegradation of the luminescent polymers, a deleterious effect owing to a concomitant action of oxygen and light. To explain such effect we proposed a model based on the properties of individual cromophores of the molecules, and in the incorporation of ketone groups (C=O), cleaving the vinyl C=C bonds. The luminescent devices were electrically and optically characterized. The current density vs. voltage and complex impedance were fit by macroscopic models taking into account a hopping process, and an equivalent circuit was also used to study ITO/polymer/metal structures. Finally, the field-effect transistor made by poly(o-methoxyaniline) were experimentally studied and a model that assumes gradients of carrier density and mobility orthogonal to the film surface fit with good agreement the ISD vs. VSD for different gate voltages, VG.
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Color tuning of organic light emitting devicesJokinen, K. (Karoliina) 08 August 2017 (has links)
Abstract
This thesis reports the investigation of color tuning of two types of organic light emitting devices, transistors (OLETs) and diodes (OLEDs). Voltage tunable two color light emission was demonstrated for OLETs. For OLEDs, two kinds of color tuning methods were presented. For these, color tuning was realized using thermal annealing which changes the light emission color of the devices permanently.
The two color light emission of the OLETs, employing a three-layer heterostructure device configuration, occurs in red and green. The device structure was first utilized for producing red light emission originating from a light emission layer made of Alq3:DCM that was deposited between the hole and electron transport layers made of DH-4T and DFH-4T, respectively. After modifying the fabrication process in order to raise the device performance by acquiring smoother active layers green light could also be produced by the devices. Green light emission originated from the electron transport layer. This took place during the electron transport mode, while the red emission was apparent while hole transport was active. The color of the light emission was therefore demonstrated as being tunable by voltage.
For OLEDs, devices with one active polymeric layer, undoped and doped, were investigated. The undoped OLEDs had the light emission layer made of blue light emitting polyfluorene PFO. The OLEDs suffered from keto-defects shifting their light emission color from blue to greenish shade, a common problem occurring in widely used blue light emitting polyfluorenes. The work conducted and reported in this thesis demonstrated that thermal annealing can be used for diminishing this undesired green emission. For the doped OLEDs with the light emission layer made of a PFO:F8BT blend, color tuning was realized using thermal annealing as well. As a result of exposure to thermal treatment, the light emission color of these devices which was green as fabricated was converted to white. The phenomenon behind this effect was explained by phase separation between the host and dopant polymers of the light emission layer. / Tiivistelmä
Tässä väitöskirjatyössä tutkitaan orgaanisten valoa emittoivien transistoreiden (OLET) ja diodien (OLED) värinsäätöä. Työssä tehtiin kolmikerrosrakenteisia OLETeja, jotka kykenevät emittoimaan valoa kahdella värillä ja joiden emittointiväri on jännitesäädettävissä. OLEDien osalta toteutettiin kaksi erilaista värinsäätömenetelmää, joissa molemmissa hyödynnettiin kuumennusta pysyvän värinvaihdon aikaansaamiseksi.
Tutkitut OLETit emittoivat punaista ja vihreää valoa. Aluksi tutkittiin vastaavia komponentteja, jotka emittoivat vain punaista valoa. Näissä komponenteissa punaisen valon tuotti keskimmäinen valoemitterinä toiminut kerros (Alq3:DCM), jonka ala- ja yläpuolella olivat aukko- ja elektronijohtavat kerrokset (DH-4T ja DFH-4T). Komponenteilla saatiin tuotettua myös vihreää valoa, kun valmistusprosessia kehitettiin tasaisempien aktiivisten materiaalikerrosten valmistamiseksi. Vihreän valon todettiin olevan elektronijohtavan kerroksen tuottamaa. Kaksiväriemittoiva OLET tuotti vihreää valoa ollessaan elektronijohtavassa tilassa, ja punaista valoa aukkojohtavassa tilassa, emittointivärin ollessa näin jännitesäädettävissä.
Työssä tutkittujen OLEDien valon emittointi perustui polymeerikerrokseen, joka oli toisissa OLEDeissa seostamaton ja toisissa seostettu. Seostamattomien OLEDien aktiivinen kerros oli tehty sinistä valoa tuottavasta polyfluoreenista (PFO), jossa usein ilmenee keto-virheitä, joiden vuoksi PFO:sta tehtyjen OLEDien valo muuttuu sinisestä vihertäväksi. Työssä osoitettiin, että kuumennusta voidaan käyttää sinisen emittointivärin palauttamiseen. Seostettujen OLEDien (PFO:F8BT) osalta kuumennusta käytettiin komponenttien emittointivärin muuttamiseksi alkuperäisestä emittointiväristä vihreästä valkoiseksi. Tämä ilmiö selitettiin valoa emittoivan kerroksen polymeerien välisellä faasierkaantumisella.
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Optimisation des matériaux des électrodes dans les diodes électroluminescentes organiques et les cellules solaires organiquesBejbouji, Habiba 04 December 2009 (has links)
Ce travail porte dans un premier temps sur l’optimisation du matériau constituant la couche d’injection des trous dans les diodes électroluminescentes organiques (OLEDs) et les cellules solaires organiques (OPVCs). Les Polyanilines (PANIs) utilisées dans ce travail sont dispersées dans différents solvants organiques ou dans l'eau. L’effet de l’épaisseur, de la morphologie et de la conductivité des films de PANI sur l’efficacité des cellules solaires a été étudié. Les résultats montrent que la conductivité et l’épaisseur des films de PANI affectent énormément l’efficacité des dispositifs OLEDs ou OPVCs. Le dopant et le solvant utilisés dans la synthèse de la dispersion de PANI jouent aussi un rôle important. Dans un second temps, différentes PANIs ainsi que des latex de PEDOT et des nanotubes de carbone ont été utilisés seuls en tant qu'électrode dans le but d'accéder à des dispositifs "tout polymère". L’influence du pH, de la conductivité, du travail de sortie, la nature du dopant et du solvant sur les propriétés de l’injection de charge ont été analysés. / The optimization of hole injection materials in organic light emitting diodes (OLEDs) and organic photovoltaic cells (OPVCs) is reported. Water and organic solvent-based PANIs were used. We have studied the influence of the thickness, the morphology and the conductivity of PANI films in (OPVCs) performances. The results show that the conductivity and the thickness of the PANI film greatly affect (OLED) and (OPVCs) effectiveness. The dopant and the solvent used in the synthesis of PANI dispersion also play an important role. PANI and PEDOT dispersions as well as carbon nanotube were also used as electrodes without ITO. The effect of pH, conductivity, the work function, the nature of the dopant and the solvent in the injection property were analyzed.
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Světelný zdroj s nastavitelnou intenzitou osvětlení / A light source with variable intensityKoždoň, Jakub January 2014 (has links)
This work is focused on description how the light impact human live, description of light sources and finally design and construction of light source with adjustable colour temperature and luminous flux. In introduction is mentioned the process of vision and how the light impact humans. In next part is characterization of currently used light sources, their construction, properties, benefits and drawback with their main parameters. Important part of this chapter is more extensive description of light emitting diodes with their operational parameters. The last two parts is focused on design and measuring the parameters of created light source with adjustable colour temperature and luminous flux and evaluating the results.
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Fotoluminescencija i Ramanova spektroskopija specifičnih kompleksnih organometalnih jedinjenja na bazi cinka, kobalta i bakra pogodnih za primenu u organskim svetlećim diodama / Photoluminescence and Raman spectroscopy of specific complexcompounds based on zinc, cobalt and copper suitable for application inorganic light emitting diodesJelić Miodrag 30 May 2017 (has links)
<p>U okviru doktorske disertacije predstavljene su elektronska i fononska struktura odabranih organometalnih materijala koji u svom sastavu imaju metale cink, kobalt ili bakar i organsko jedinjenje piridoksalaminogvanidin (PLAG). Predstavljene su realizacija i karakteristike organske svetleće diode zasnovane na najboljem od ispitivanih materijala. Urađena je detaljna analiza fotoluminescentnih spektara i njihovo razlaganje na proste komponente koristeći Lorencov model. Izvršeno je poređenje sa od ranije poznatim materijalom koji pokazuje visok stepen luminescencije. S obzirom da istraživanja vezana za organske svetleće diode uzimaju sve veći zamah i da ove diode postaju sve prisutnije u industrijskoj serijskoj proizvodnji, napravljena je detaljna analiza ove tehnologije i mehanizama koji se kriju iza nje. Urađeno je podrobno istraživanje kako na nivou elektrona u datim supstancama, tako i na nivou sloja organske svetleće diode. Na kraju je izvršena analiza rada diode sa integrisanim slojem sa materijalom koji u sebi sadrži cink i PLAG.</p> / <p>In this thesis electronic and phonon structure of specific organometallic<br />materials which have zinc, cobalt, copper metals and organic compound<br />pyridoxalaminoguanidin are presented. Implementation and characteristics of<br />organic light emitting diode based on the best material among examined<br />ones are also showed up. Detailed analysis of photoluminescence spectra<br />was done and its decomposition to its elementar components using<br />Lorentzian multipeak method. Comparison to well-known material that shows<br />high level of luminescence was implemented. In accordance to the fact that<br />research of organic light emitting diodes expands and that these diodes start<br />to be more present in industrial serial production, detailed analysis of this<br />technology and mechanisms behind it are made. Thorough research was<br />done both on electron level in these substances and organic light emitting<br />diode layer level. Finally, analysis of diode operation with integrated layer<br />made of material which includes zinc and pyridoxalaminoguanidin compound<br />is implemented.</p>
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Phototrophic growth of Arthrospira platensis in a respiration activity monitoring system for shake flasks (RAMOS)Socher, Maria Lisa, Lenk, Felix, Geipel, Katja, Schott, Carolin, Püschel, Joachim, Haas, Christiane, Grasse, Christiane, Bley, Thomas, Steingroewer, Juliane January 2014 (has links)
Optimising illumination is essential for optimising the growth of phototrophic cells and their production of desired metabolites and/or biomass. This requires appropriate modulation of light and other key inputs and continuous online monitoring of their metabolic activities. Powerful non-invasive systems for cultivating heterotrophic organisms include shake flasks in online monitoring units, but they are rarely used for phototrophs because they lack the appropriate illumination design and necessary illuminatory power.
This study presents the design and characterisation of a photosynthetic shake flask unit, illuminated from below by warm white light-emitting diodes with variable light intensities up to 2300 μmol m-2 s-1. The photosynthetic unit was successfully used, in combination with online monitoring of oxygen production, to cultivate Arthrospira platensis.
In phototrophic growth under continuous light and a 16 h light/8 h dark cycle (light intensity: 180 μmol m-2 s-1), the oxygen transfer rate and biomass-related oxygen production were - 1.5 mmol L-1 h-1 and 0.18 mmol O2 gx-1 h-1, respectively. The maximum specific growth rate was 0.058 h-1, during the exponential growth phase, after which the biomass concentration reached 0.75 g L-1.
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