No description available.

Os materiais CaWO4:TR3+, CaMoO4:TR3+, Ca(MO4):TR3+ (TR: Pr3+, Sm3+, Eu3+, Tb3+ e Dy3+) (M: W e Mo) foram preparados pelo método da coprecipitação acoplado ao método ultrassônico a fim de estudar suas aplicações em materiais fotônicos aplicados em LEDs. Após a reação de precipitação, o material foi filtrado sob pressão reduzida, lavado com água destilada, seco e armazenado em dessecador a vácuo. Esses materiais sem tratamento térmico se mostraram como pós brancos, de aspecto uniforme, cristalinos, não higroscópicos e insolúveis em solventes polares e apolares. Após a síntese, os materiais foram submetidos a tratamento térmico em forno resistivo (1000 °C / 3 h) e sob radiação micro-ondas (5 min; ~1100 °C e 22 min; ~1200 °C). Este método oferece muitas vantagens se comparado aos métodos convencionais, tais como: método simples de operação, baixo custo, tempo curto de síntese e procedimento ambientalmente correto. Os materiais tratados sob altas temperaturas foram comparados com aqueles materiais sem tratamento térmico. Os materiais foram caracterizados pelas seguintes técnicas: espectroscopia de absorção no infravermelho (IV), análise termogravimetria (TG), difratometria de raios X - método do pó (DRX), microscopia eletrônica de varredura (MEV) e energia dispersiva de raios X (EDS). Os picos dentro do difratograma de raios X foram indexados na estrutura tetragonal scheelita I41/a. As propriedades fotoluminescentes dos compostos Ca(MO4) (M: W e Mo) dopados com Dy3+ e codopados com Eu3+ foram investigadas com base nas transições intraconfiguracionais 4f dos íons TR3+. Os espectros de excitação apresentaram bandas largas na região do UV, atribuídas às bandas de transferência de carga LMCT O→W; O→Mo e O→Eu3+. Os espectros de excitação dos fósforos dopados com Tb3+ apresentaram as bandas de absorção largas atribuídas à transferência de carga LMCT O→W6+ (5d) e O→Mo6+ (4d) sobrepostas às transições 4f8→4f75d1 do íon Tb3+ e também picos finos oriundos das transições 4f referentes aos íons Pr3+ (4f2), Sm3+ (4f5), Eu3+ (4f6), Tb3+ (4f8) e Dy3+ (4f9). O material CaWO4:Eu3+ submetido a tratamento térmico em forno resistivo (1000 °C / 3 h) apresentou o fenômeno da luminescência persistente de cor vermelha. O material triplamente dopado CaWO4:Eu3+,Tb3+,Dy3+ apresentou cores ajustáveis, indo do branco quente ao branco frio, com grande potencial para aplicação em materiais fotônicos para iluminação no estado sólido. Também, os materiais CaWO4:Eu3+,Tb3+,Dy3+ e Ca(MO4):Dy3+,Eu3+ (M: W e Mo) foram montados a base de um polímero óptico de silicone e utilizando um LED de GaN de alta potência, gerando luz branca fria e quente de altas intensidades. As coordenadas CIE (Commission Internationale l\'Eclairage) sugerem emissões multicolores dos sistemas dopados com diferentes íons TR: Pr3+, Sm3+, Eu3+, Tb3+, Dy3+. Esses materiais se mostraram promissores em aplicação de materiais de iluminação do estado sólido, com a vantagem de serem preparados de forma rápida, em poucas etapas, com alto rendimento e serem ambientalmente amigáveis. / The materials CaWO4:TR3+, CaMoO4:TR3+, Ca(MO4):TR3+ (TR: Pr3+, Sm3+, Eu3+, Tb3+ e Dy3+) (M: W and Mo) were prepared by the coprecipitation and ultrasonic method in order to study their applications in photonic materials applied in LEDs. After the precipitation reaction, the material was filtered under reduced pressure, washed with distilled water, dried and stored in vacuum desiccator. These as prepared materials were shown to be white powders, uniform in appearance, crystalline, non-hygroscopic and insoluble in polar and apolar solvents. After the synthesis the materials were submitted to thermal treatment in resistive furnace (1000 °C / 3 h) and also under microwave radiation (5 min; 1100 °C e 22 min; 1200 °C). This method offers many advantages compared to conventional methods, such as: simple operation method, low cost, brief synthesis time and environmentally correct procedure. The materials treated under high temperatures were compared with those materials without heat treatment. In the characterization of these phosphors, the following techniques were used: infrared (IR) absorption spectroscopy, thermogravimetric (TG) analysis, X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS). The X-ray diffraction peaks were indexed in the scheelite tetragonal structure. The photoluminescent properties of the compounds Ca(MO4) (M: W and Mo) Dy3+ doped and Eu3+ codoped were investigated based on the intraconfiguration transitions 4f of the TR3+ ions. Excitation spectra showed broad bands in the UV region attributed to the LMCT O → W charge transfer bands; O → Mo and O Eu3+. The excitation spectra of the phosphors doped with Tb3+ showed the wide absorption bands attributed to the charge transfer LMCT O2- (2p)W6+ (5d) and O2-(2p)Mo6+ (4d) overlapping the transitions 4f8→4f75d1 of Tb3+ ion and also fine peaks originating from the 4f transitions referring to ions Pr3+ (4f2), Sm3+ (4f5), Eu3+ (4f6), Tb3+ (4f8) and Dy3+ (4f9). The CaWO4:Eu3+ material submitted to thermal treatment in a resistive oven (1000 °C / 3 h) exhibited the phenomenon of persistent red color luminescence. The triply-doped CaWO4:Eu3+,Tb3+,Dy3+ showed color matching, ranging from warm white to cool white, promising to be an excellent material to be applied in photonic materials for solid state lighting. Also, the materials CaWO4:Eu3+,Tb3+,Dy3+ and Ca(MO4):Dy3+,Eu3+ (M: W and Mo) were assembled on the basis of a silicone optical polymer and using a high power GaN LED, generating warm white and cold white light of high intensities. The CIE (Commission Internationale l\'Eclairage) coordinates suggest multicolored emissions of multicolor systems doped with various TR3+ ions: TR3+: Pr3+, Sm3+, Eu3+, Tb3+, Dy3+. These materials have proven to be promising in the application of solid state lighting materials, with the advantage of being quickly prepared, in a few steps, high performance and environmentally friendly.

Os materiais CaWO4:TR3+, CaMoO4:TR3+, Ca(MO4):TR3+ (TR: Pr3+, Sm3+, Eu3+, Tb3+ e Dy3+) (M: W e Mo) foram preparados pelo método da coprecipitação acoplado ao método ultrassônico a fim de estudar suas aplicações em materiais fotônicos aplicados em LEDs. Após a reação de precipitação, o material foi filtrado sob pressão reduzida, lavado com água destilada, seco e armazenado em dessecador a vácuo. Esses materiais sem tratamento térmico se mostraram como pós brancos, de aspecto uniforme, cristalinos, não higroscópicos e insolúveis em solventes polares e apolares. Após a síntese, os materiais foram submetidos a tratamento térmico em forno resistivo (1000 °C / 3 h) e sob radiação micro-ondas (5 min; ~1100 °C e 22 min; ~1200 °C). Este método oferece muitas vantagens se comparado aos métodos convencionais, tais como: método simples de operação, baixo custo, tempo curto de síntese e procedimento ambientalmente correto. Os materiais tratados sob altas temperaturas foram comparados com aqueles materiais sem tratamento térmico. Os materiais foram caracterizados pelas seguintes técnicas: espectroscopia de absorção no infravermelho (IV), análise termogravimetria (TG), difratometria de raios X - método do pó (DRX), microscopia eletrônica de varredura (MEV) e energia dispersiva de raios X (EDS). Os picos dentro do difratograma de raios X foram indexados na estrutura tetragonal scheelita I41/a. As propriedades fotoluminescentes dos compostos Ca(MO4) (M: W e Mo) dopados com Dy3+ e codopados com Eu3+ foram investigadas com base nas transições intraconfiguracionais 4f dos íons TR3+. Os espectros de excitação apresentaram bandas largas na região do UV, atribuídas às bandas de transferência de carga LMCT O→W; O→Mo e O→Eu3+. Os espectros de excitação dos fósforos dopados com Tb3+ apresentaram as bandas de absorção largas atribuídas à transferência de carga LMCT O→W6+ (5d) e O→Mo6+ (4d) sobrepostas às transições 4f8→4f75d1 do íon Tb3+ e também picos finos oriundos das transições 4f referentes aos íons Pr3+ (4f2), Sm3+ (4f5), Eu3+ (4f6), Tb3+ (4f8) e Dy3+ (4f9). O material CaWO4:Eu3+ submetido a tratamento térmico em forno resistivo (1000 °C / 3 h) apresentou o fenômeno da luminescência persistente de cor vermelha. O material triplamente dopado CaWO4:Eu3+,Tb3+,Dy3+ apresentou cores ajustáveis, indo do branco quente ao branco frio, com grande potencial para aplicação em materiais fotônicos para iluminação no estado sólido. Também, os materiais CaWO4:Eu3+,Tb3+,Dy3+ e Ca(MO4):Dy3+,Eu3+ (M: W e Mo) foram montados a base de um polímero óptico de silicone e utilizando um LED de GaN de alta potência, gerando luz branca fria e quente de altas intensidades. As coordenadas CIE (Commission Internationale l\'Eclairage) sugerem emissões multicolores dos sistemas dopados com diferentes íons TR: Pr3+, Sm3+, Eu3+, Tb3+, Dy3+. Esses materiais se mostraram promissores em aplicação de materiais de iluminação do estado sólido, com a vantagem de serem preparados de forma rápida, em poucas etapas, com alto rendimento e serem ambientalmente amigáveis. / The materials CaWO4:TR3+, CaMoO4:TR3+, Ca(MO4):TR3+ (TR: Pr3+, Sm3+, Eu3+, Tb3+ e Dy3+) (M: W and Mo) were prepared by the coprecipitation and ultrasonic method in order to study their applications in photonic materials applied in LEDs. After the precipitation reaction, the material was filtered under reduced pressure, washed with distilled water, dried and stored in vacuum desiccator. These as prepared materials were shown to be white powders, uniform in appearance, crystalline, non-hygroscopic and insoluble in polar and apolar solvents. After the synthesis the materials were submitted to thermal treatment in resistive furnace (1000 °C / 3 h) and also under microwave radiation (5 min; 1100 °C e 22 min; 1200 °C). This method offers many advantages compared to conventional methods, such as: simple operation method, low cost, brief synthesis time and environmentally correct procedure. The materials treated under high temperatures were compared with those materials without heat treatment. In the characterization of these phosphors, the following techniques were used: infrared (IR) absorption spectroscopy, thermogravimetric (TG) analysis, X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS). The X-ray diffraction peaks were indexed in the scheelite tetragonal structure. The photoluminescent properties of the compounds Ca(MO4) (M: W and Mo) Dy3+ doped and Eu3+ codoped were investigated based on the intraconfiguration transitions 4f of the TR3+ ions. Excitation spectra showed broad bands in the UV region attributed to the LMCT O → W charge transfer bands; O → Mo and O Eu3+. The excitation spectra of the phosphors doped with Tb3+ showed the wide absorption bands attributed to the charge transfer LMCT O2- (2p)W6+ (5d) and O2-(2p)Mo6+ (4d) overlapping the transitions 4f8→4f75d1 of Tb3+ ion and also fine peaks originating from the 4f transitions referring to ions Pr3+ (4f2), Sm3+ (4f5), Eu3+ (4f6), Tb3+ (4f8) and Dy3+ (4f9). The CaWO4:Eu3+ material submitted to thermal treatment in a resistive oven (1000 °C / 3 h) exhibited the phenomenon of persistent red color luminescence. The triply-doped CaWO4:Eu3+,Tb3+,Dy3+ showed color matching, ranging from warm white to cool white, promising to be an excellent material to be applied in photonic materials for solid state lighting. Also, the materials CaWO4:Eu3+,Tb3+,Dy3+ and Ca(MO4):Dy3+,Eu3+ (M: W and Mo) were assembled on the basis of a silicone optical polymer and using a high power GaN LED, generating warm white and cold white light of high intensities. The CIE (Commission Internationale l\'Eclairage) coordinates suggest multicolored emissions of multicolor systems doped with various TR3+ ions: TR3+: Pr3+, Sm3+, Eu3+, Tb3+, Dy3+. These materials have proven to be promising in the application of solid state lighting materials, with the advantage of being quickly prepared, in a few steps, high performance and environmentally friendly.

A rede de coordenação constituída por íons bismuto trivalente e ácido piromelítico (H4Pyr), [Bi(HPyr)], foi utilizada com sucesso como matriz hospedeira para a incorporação in situ dos íons terras raras trivalentes TR3+: Sm3+, Eu3+, Tb3+ e Dy3+. O método de alto rendimento para a síntese permitiu preparar e estudar a pureza de fase e cristalinidade das séries de amostras, acelerando e facilitando a comparação entre os parâmetros de síntese. As técnicas de espectroscopia de absorção no infravermelho, análise elementar e termogravimétrica, microscopia eletrônica de varredura e espectroscopia de energia dispersiva de raios X, bem como a difração de raios X de pó e o refinamento de Le Bail dos compostos indicaram que a dopagem não afetou a estrutura, cristalinidade, morfologia e estabilidade térmica da matriz. O estudo das propriedades espectroscópicas da matriz [Bi(HPyr)] não dopada e dopada com íons TR3+ permitiu a investigação dos processos de sensibilização do íons ativadores TR3+. As propriedades espectroscópicas características do íon Eu3+ foi utilizada para estudar o sítio e ambiente de coordenação dos dopantes por meio dos parâmetros de intensidades experimentais Ωλ (λ: 2 and 4), além do rendimento quântico intrínseco (QEUEU ) do material [Bi(HPyr)] mono dopado com Eu3+. A sintonização da cor de emissão pela mudança da concentração relativa dos íons dopantes é investigada para os sistemas duplamente dopados com os íons Tb3+:Eu3+, Tb3+:Sm3+, Dy3+:Eu3+ e Dy3+:Sm3+. Os sistemas contendo íons Dy3+ apresentam diferentes tonalidades de emissão branca e ampla faixa de temperatura de cor correlata (CCT - 2500 a 7500 K), sendo promissores para o desenvolvimento de dispositivos emissores de luz branca de fase única. / The coordination network consisting of trivalent bismuth ions and pyromellitic acid (H4Pyr), [Bi(HPyr)], was successfully applied as host matrix for in situ incorporation of the trivalent rare earth ions RE3+: Sm3+, Eu3+, Tb3+ and Dy3+. The high-throughput methods for hydrothermal synthesis allowed to prepare and study phase purity and crystallinity of sample series, accelerating and facilitating the comparison between the synthesis parameters. Infrared absorption spectroscopy, elemental and thermogravimetric analysis, scanning electron microscopy and energy-dispersive X-ray spectroscopy, as well as powder X-ray diffraction and the Le Bail refinement of the compounds indicated that doping did not affect the structure, crystallinity, morphology and thermal stability of the matrix. The study of the spectroscopic luminescence properties of the nondoped and doped [Bi(HPyr)] allowed the investigation of the sensitization processes of dopant RE3+ ions. The characteristic spectroscopic properties of the Eu3+ ion were used to study the incorporation site and coordination environment of the dopant by the calculation of the experimental intensity parameters Ωλ (λ: 2 and 4), besides the intrinsic quantum yield (QEUEU) of the Eu3+ single-doped [Bi(HPyr)]. Straightforward emission color tuning by changing the relative concentrations of the dopant ions is possible and has been studied for the systems double-doped with Tb3+:Eu3+, Tb3+:Sm3+, Dy3+:Eu3+ and Dy3+:Sm3+ ions. The Dy-containing systems show different shades of white emission and a wide range of correlated color temperatures (CCT - 2500 to 7500 K), hence being a promising candidate for the development of single-phase white light emitting devices.

A rede de coordenação constituída por íons bismuto trivalente e ácido piromelítico (H4Pyr), [Bi(HPyr)], foi utilizada com sucesso como matriz hospedeira para a incorporação in situ dos íons terras raras trivalentes TR3+: Sm3+, Eu3+, Tb3+ e Dy3+. O método de alto rendimento para a síntese permitiu preparar e estudar a pureza de fase e cristalinidade das séries de amostras, acelerando e facilitando a comparação entre os parâmetros de síntese. As técnicas de espectroscopia de absorção no infravermelho, análise elementar e termogravimétrica, microscopia eletrônica de varredura e espectroscopia de energia dispersiva de raios X, bem como a difração de raios X de pó e o refinamento de Le Bail dos compostos indicaram que a dopagem não afetou a estrutura, cristalinidade, morfologia e estabilidade térmica da matriz. O estudo das propriedades espectroscópicas da matriz [Bi(HPyr)] não dopada e dopada com íons TR3+ permitiu a investigação dos processos de sensibilização do íons ativadores TR3+. As propriedades espectroscópicas características do íon Eu3+ foi utilizada para estudar o sítio e ambiente de coordenação dos dopantes por meio dos parâmetros de intensidades experimentais Ωλ (λ: 2 and 4), além do rendimento quântico intrínseco (QEUEU ) do material [Bi(HPyr)] mono dopado com Eu3+. A sintonização da cor de emissão pela mudança da concentração relativa dos íons dopantes é investigada para os sistemas duplamente dopados com os íons Tb3+:Eu3+, Tb3+:Sm3+, Dy3+:Eu3+ e Dy3+:Sm3+. Os sistemas contendo íons Dy3+ apresentam diferentes tonalidades de emissão branca e ampla faixa de temperatura de cor correlata (CCT - 2500 a 7500 K), sendo promissores para o desenvolvimento de dispositivos emissores de luz branca de fase única. / The coordination network consisting of trivalent bismuth ions and pyromellitic acid (H4Pyr), [Bi(HPyr)], was successfully applied as host matrix for in situ incorporation of the trivalent rare earth ions RE3+: Sm3+, Eu3+, Tb3+ and Dy3+. The high-throughput methods for hydrothermal synthesis allowed to prepare and study phase purity and crystallinity of sample series, accelerating and facilitating the comparison between the synthesis parameters. Infrared absorption spectroscopy, elemental and thermogravimetric analysis, scanning electron microscopy and energy-dispersive X-ray spectroscopy, as well as powder X-ray diffraction and the Le Bail refinement of the compounds indicated that doping did not affect the structure, crystallinity, morphology and thermal stability of the matrix. The study of the spectroscopic luminescence properties of the nondoped and doped [Bi(HPyr)] allowed the investigation of the sensitization processes of dopant RE3+ ions. The characteristic spectroscopic properties of the Eu3+ ion were used to study the incorporation site and coordination environment of the dopant by the calculation of the experimental intensity parameters Ωλ (λ: 2 and 4), besides the intrinsic quantum yield (QEUEU) of the Eu3+ single-doped [Bi(HPyr)]. Straightforward emission color tuning by changing the relative concentrations of the dopant ions is possible and has been studied for the systems double-doped with Tb3+:Eu3+, Tb3+:Sm3+, Dy3+:Eu3+ and Dy3+:Sm3+ ions. The Dy-containing systems show different shades of white emission and a wide range of correlated color temperatures (CCT - 2500 to 7500 K), hence being a promising candidate for the development of single-phase white light emitting devices.

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.

White organic light-emitting diodes (OLEDs) are promising candidates for future solid-state lighting applications and backplane illumination in large-area displays. One very specific feature of OLEDs, which is currently gaining momentum, is that they can enable tunable white light emission. This feature is conventionally realized either through the vertical stacking of independent OLEDs emitting different colors or in lateral arrangement of OLEDs. The vertical design is optically difficult to optimize and often results in efficiency compromises between the units. In contrast, the lateral concept introduces severe area losses to dark regions between the subunits, which requires a significantly larger overall device area to achieve equal brightness. Here we demonstrate a color-tunable, two-color OLED device realized by side-by-side alignment of yellow and blue p-i-n OLEDs structured down to 20 μm by a simple and up-scalable orthogonal photolithography technique. This layout eliminates the problems of conventional lateral approaches by utilizing all area for light emission. The corresponding emission of the photo-patterned two-unit OLED can be tuned over a wide range from yellow to white to blue colors. The independent control of the different units allows the desired overall spectrum to be set at any given brightness level. Operated as a white light source, the microstructured OLED reaches a luminous efficacy of 13 lm W−1 at 1000 cd m−2 without an additional light outcoupling enhancement and reaches a color rendering index of 68 when operated near the color point E. Finally, we demonstrate an improved device lifetime by means of size variation of the subunits.

White organic light-emitting diodes (OLEDs) are promising candidates for future solid-state lighting applications and backplane illumination in large-area displays. One very specific feature of OLEDs, which is currently gaining momentum, is that they can enable tunable white light emission. This feature is conventionally realized either through the vertical stacking of independent OLEDs emitting different colors or in lateral arrangement of OLEDs. The vertical design is optically difficult to optimize and often results in efficiency compromises between the units. In contrast, the lateral concept introduces severe area losses to dark regions between the subunits, which requires a significantly larger overall device area to achieve equal brightness. Here we demonstrate a color-tunable, two-color OLED device realized by side-by-side alignment of yellow and blue p-i-n OLEDs structured down to 20 μm by a simple and up-scalable orthogonal photolithography technique. This layout eliminates the problems of conventional lateral approaches by utilizing all area for light emission. The corresponding emission of the photo-patterned two-unit OLED can be tuned over a wide range from yellow to white to blue colors. The independent control of the different units allows the desired overall spectrum to be set at any given brightness level. Operated as a white light source, the microstructured OLED reaches a luminous efficacy of 13 lm W−1 at 1000 cd m−2 without an additional light outcoupling enhancement and reaches a color rendering index of 68 when operated near the color point E. Finally, we demonstrate an improved device lifetime by means of size variation of the subunits.

A straightforward, rapid method to create colloidally stable and brightly luminescent core/shell CdSe-based nanoplatelets (NPLs) with fluorescence quantum yields (QYs) up to 50% is demonstrated. A layer-by-layer deposition technique based on a two-phase mixture ‒ consisting of a nonpolar phase which includes the NPLs, and a saturated ionic polar phase ‒ to separate the reagents and hinder the nucleation of the shell material is used. The deposition of the first sulfur layer leads to a significant red-shift (by more than 100 nm) of the optical absorption and emission of the NPLs. Hence, by varying either the sulfur precursor content or the reaction time one can precisely and continuously tune the absorption and emission maxima from 520 to 630 nm. This evolution of the absorption onset during the shell growth is explained quantitatively using density-functional theory and atomistic statistical simulations. The emission can be further enhanced by exposure of the NPL solution to ambient sunlight. Finally, it is demonstrated that the core/shell NPLs can be transferred from the organic solution to aqueous media with no reduction of their QY that opens the door to a broad range of practical applications.

Kanalrhodopsine (ChRs) sind lichtaktivierte Ionenkanäle motiler Algen. Heterolog exprimiert erlauben sie es, Ionenflüsse durch Licht zu steuern. Bevorzugt geleitet werden von den meisten ChRs Protonen. Ausprägung und Wirkung lichtaktivierter Protonenflüsse sowie der molekulare Mechanismus protonenselektiver ChRs werden in vorliegender Arbeit untersucht und zur Entwicklung neuer optogenetischer Werkzeuge genutzt. Eine besonders hohe Protonenselektivität zeigten die grün- und rotlicht-aktivierten Kanäle CsChR und Chrimson aus den Algen Chloromonas subdivisa und Chlamydomonas noctigama. Im spektroskopisch detailliert untersuchten CrChR2 aus Chlamydomonas reinhardtii änderte sich die Protonenselektivität nach Anregung mit einem ns-Laserblitz sogar innerhalb eines Aktivierungszyklus und war insbesondere nach Öffnung des Kanals sowie in Folge der Lichtadaptation hoch. Als unentbehrlich für eine effiziente Protonenleitung erwiesen sich in allen drei Kanälen konservierte, titrierbare Reste entlang der Pore, deren individuelle Bedeutung für die Protonenleitung sich je nach Protein wesentlich unterschied. Entsprechend genügte in Chrimson der Austausch einzelner Glutaminsäuren des extrazellulären Halbkanals, dieses in einen grün- oder rotlichtaktivierten Natriumkanal zu transformieren. Aminosäuresubstitutionen der unmittelbaren Retinalumgebung verschoben hingegen das Aktionsmaximum von Chrimson röter als 600 nm und damit röter als in allen bisher beschriebenen ChRs. In Chrimson versperrt hierbei ein zusätzliches äußeres Tor den extrazellulär Halbkanal, während die Retinalbindetasche in Struktur und funktionaler Bedeutung der einzelnen Reste wesentlich jener der Protonenpumpe Bacteriorhodopsin ähnelt. Als Zwei-Komponenten-Optogenetik wurden schließlich protonen-, kationen- und anionenleitende ChRs unterschiedlicher Farbsensitivität fusioniert sowie lichtgetriebene Protonenpumpen mit protonenaktivierten Ionenkanälen kombiniert und neue optogenetische Perspektiven eröffnet. / Channelrhodopsins (ChRs) are light-gated ion channels from green algae. Expressed in host cells they are used to control ion fluxes by light and are widely applied in Neurosciences. Although generally classified as either cation or anion channels, most ChRs preferentially conduct protons. This thesis compares proton conductance of different ChRs, examines the molecular mechanism of proton selective ChRs and explores the usage of light regulated proton fluxes in two-component-optogenetics. Proton selectivity varied strongly among different ChRs and was most pronounced for the green- and red-light activated channels CsChR and Chrimson from the algae Chloromonas subdivisa and Chlamydomonas noctigama, that conducted predominantly protons even at high pH. In CrChR2 from Chlamydomonas reinhardtii proton selectivity also changed during a single activation cycle and was especially high directly after channel opening and later on following light adaptation. In all three channels efficient proton conductance depended on conserved titratable residues along the pore with different contribution of the individual side chains in each protein. The substitution of single glutamic acids in the extracellular half pore converted Chrimson into a green or red-light activated sodium channel. A single point mutation close to the retinal chromophore shifted peak absorption of Chrimson beyond 600 nm - further red than all other cation conducting ChRs. Whereas the retinal binding pocket of Chrimson resembles the proton pump Bacteriorhodpsin, the overall pore structure corresponds to other ChRs, but features an additional outer gate, that occludes the extracellular half pore and is important for both, proton selectivity and red light absorption. Finally different Two-Component-Optogenetic approaches combined proton and anion selective ChRs of distinct colour as well as light-driven proton pumps and proton-activated ion channels with major prospect for future optogenetic applications.