Solution processable double layer organic light emitting diodes (OLEDs) based on 6-N,N-arylsubstituted-1H-pyrazolo[3,4-b]quinolines

Three 1H-pyrazolo[3,4-b]quinolines (PQs) with N,N-diarylamine moiety were synthesized. They were used as dopants in poly(9-N-vinylcarbazole) (PVK) matrice. An additional star burst oligoquinoline TRI-Q electron transporting layer was deposited on emission layer from solution. The devices with configuration ITO/PEDOT:PSS/PVK-PQ/TRI-Q/Ca/Al show bright green emission with luminance L = 355–806 cd m−2

Trifluoromethyl substituted derivatives of pyrazoles as materials for photovoltaic and electroluminescent applications

New 6-CF3-1H-pyrazolo[3,4-b]quinolines with a methyl and/or phenyl group attached to the pyrazole core (Molx (x = 1, 2, 3, 4)) were synthesized and characterized in terms of their optoelectronic applications: photovoltaic and electroluminescence. The fluorescence emissions of the investigated phenyl-decorated pyrazoloquinolines is caused by the photoinduced charge transfer p process occurring between the phenyl substituent and the pyrazoloquinoline core, while 1,3-dimethyl-6-CF3-1H-pyrazolo[3,4-b]quinoline exhibits an π,π*-type emission. The number of phenyls and their substitution positions modulate both emission properties and HOMO energy levels. Next, the bulk heterojunction BHJ solar cells based on 1H-pyrazolo[3,4-b] quinoline derivatives with architecture ITO/PEDOT:PSS/PDT + Molx/Al were fabricated. The organic active layer was a blend of Molx and poly(3-decylthiophene-2,5-diyl). The complex refractive index and the layer thickness of the organic solar cells were determined using a spectroscopic ellipsometer Woollam M2000 (J.A. Woollam Co., Inc., Lincoln, NE, USA) and CompleteEASE software. For solar devices with the best value of power efficiency of approximately 0.38%, the thickness of the active layer (Mol3 + PDT) was 111 nm, with a short-circuit current density of JSC = 32.81 μA/cm2 and an open–circuit voltage of VOC = 0.78 V. Finally, we demonstrated double-layer light-emitting diodes with an organic active layer (Molx + PVK) and an electron transporting material layer, ETM (2-[3,5-bis(4-phenyl-2-quinolyl)phenyl]-4-phenylquinoline (Tris-Q). Bright bluish-green light originating from the active layer was observed in the double-layer device, ITO/PEDOT:PSS/active layer/ETM/Ca/A. The active layer was a mixture of PV-doped 1H-pyrazolo[3, 4-b]quinoline dyes. An OLED device was constructed by employing Molx as an emitter, which gave a deep bluish-green emission with the spectra range of 481–506 nm. The best value of the maximum brightness at approximately 1436.0 cd/m2 was achieved for a diode based on Mol3 (1-phenyl-3-phenyl-6-CF3-1H-pyrazolo[3,4-b]quinoline) and [R1 = Ph, R3 = Ph and R6 = CF3]. The current efficiency was up to 1.26 cd/A at 506 nm with a CIE of 0.007, 0.692

Highly Sensitive Sensor Structure Based on Sol-Gel Waveguide Films and Grating Couplers

The technologies of optical planar evanescent wave chemical and biochemical sensors require chemically resistant, high refractive index waveguide films having very good optical transmission properties. In this paper we present such two-compound SiOx:TiOy waveguide films fabricated by using the sol-gel method and the dip-coating technique. These films not only have high optical quality and low propagation losses but also an extremely high refractive index of >1.90 (λ = 632.8 nm). Further we demonstrate efficient and simple sensing structures, designed and fabricated based on these films. For this purpose, grating couplers with a period of Λ = 417 nm were fabricated on the interface between a waveguide film and cover using the single-step nanoimprint method. These sensing structures were tested as planar refractometers. The results of the theoretical analysis on the basis of which the structures were designed as well as results of their experimental characterization are presented in this work. Consequently, the relationship between parameters and the sensitivity of investigated sensing structures is discussed. As a result, the profitable properties of the designed grating coupler sensors are verified and excellent consistency between the results of the theoretical analysis and experimental results is achieved

Mode Sensitivity Exploration of Silica–Titania Waveguide for Refractive Index Sensing Applications

In this paper, a novel and cost-effective photonic platform based on silica–titania material is discussed. The silica–titania thin films were grown utilizing the sol–gel dip-coating method and characterized with the help of the prism-insertion technique. Afterwards, the mode sensitivity analysis of the silica–titania ridge waveguide is investigated via the finite element method. Silica–titania waveguide systems are highly attractive due to their ease of development, low fabrication cost, low propagation losses and operation in both visible and near-infrared wavelength ranges. Finally, a ring resonator (RR) sensor device was modelled for refractive index sensing applications, offering a sensitivity of 230 nm/RIU, a figure of merit (FOM) of 418.2 RIU−1, and Q-factor of 2247.5 at the improved geometric parameters. We believe that the abovementioned integrated photonics platform is highly suitable for high-performance and economically reasonable optical sensing devices

Laser Modified Glass for High-Performance Photovoltaic Module

The solar module output power is the power generated by all individual cells in their specific electrical circuit configuration, multiplied by the cell-to-module power ratio. The cell-to-module power ratio thus reflects the sum of the losses and gains produced by the structure of the module. The biggest process change in module design during the last few years was the introduction of half cells. Another important trend is the use of bifacial cells to build bifacial modules. These two trends increase parts of the module that correspond to the intercell gaps, and the light does not meet the cell in its path. This part of the radiation is therefore not used efficiently. Scientific efforts focus on the texturing surface of covering glass and cells, and the introduction of narrower ribbons and encapsulation materials with improved UV performance, etc. The concept of a diffusor that actively redirects light from the intercell space into the cell was proposed in the past, in the form of a micro-structured prismatic film, but this is not applicable for bifacial modules. The conclusion is that losses caused by the incidence of light on the areas of the photovoltaic panel not covered with solar cells yet are to be explored further. A sawtooth-shaped reflecting diffusor placed between cells is proposed. This article addresses the issue in a novel way, primarily because the theoretical range of the optimum sawtooth profile is defined. In the experimental part of the study, the possibility of producing such a profile directly on glass using a CO2 laser is demonstrated. The theoretical model enables discrimination between advantageous and disadvantageous sawtooth profiles. As a proof of concept, minimodules based on the optimum parameters were built and tested for their electrical performance. The result confirms that the proposed sawtooth-shaped reflecting diffusor placed between cells creates cell-to-module power gain. The proposed laser technology can be incorporated into existing production lines, and can increase the output of any photovoltaic technology, including and beyond silicon

Laser Modified Glass for High-Performance Photovoltaic Module

The solar module output power is the power generated by all individual cells in their specific electrical circuit configuration, multiplied by the cell-to-module power ratio. The cell-to-module power ratio thus reflects the sum of the losses and gains produced by the structure of the module. The biggest process change in module design during the last few years was the introduction of half cells. Another important trend is the use of bifacial cells to build bifacial modules. These two trends increase parts of the module that correspond to the intercell gaps, and the light does not meet the cell in its path. This part of the radiation is therefore not used efficiently. Scientific efforts focus on the texturing surface of covering glass and cells, and the introduction of narrower ribbons and encapsulation materials with improved UV performance, etc. The concept of a diffusor that actively redirects light from the intercell space into the cell was proposed in the past, in the form of a micro-structured prismatic film, but this is not applicable for bifacial modules. The conclusion is that losses caused by the incidence of light on the areas of the photovoltaic panel not covered with solar cells yet are to be explored further. A sawtooth-shaped reflecting diffusor placed between cells is proposed. This article addresses the issue in a novel way, primarily because the theoretical range of the optimum sawtooth profile is defined. In the experimental part of the study, the possibility of producing such a profile directly on glass using a CO2 laser is demonstrated. The theoretical model enables discrimination between advantageous and disadvantageous sawtooth profiles. As a proof of concept, minimodules based on the optimum parameters were built and tested for their electrical performance. The result confirms that the proposed sawtooth-shaped reflecting diffusor placed between cells creates cell-to-module power gain. The proposed laser technology can be incorporated into existing production lines, and can increase the output of any photovoltaic technology, including and beyond silicon