This PDF file contains the front matter associated with SPIE Proceedings Volume 10915, including the Title Page, Copyright information, Table of Contents, Author and Conference Committee lists.

Multi-photon lithography (MPL) is a laser-based method for 3D printing nanoscale devices. Since its introduction in the late 1990's, researchers across many disciplines have made exciting contributions toward its development that include extending the range of material systems available for MPL, improving the achievable resolution, and using it to create functional devices for optics, MEMS, microfluidics, sensing, and bio-engineering. MPL has been used to create conventional micro-optics, like waveguides and micro-lenses. It has also been used to fabricate devices onto novel platforms, such as the tips of optical fibers, which greatly extends the functionality of conventional optics and the range of applications they may serve. MPL is unique among existing fabrication methods in its potential for creating truly 3D structures having arbitrary shape and complexity. This is particularly well illustrated in recent reports of using MPL to create spatially-variant photonic crystals (SVPCs). SVPCs unlock new physical mechanisms to control light, particularly using self-collimation to flow beams through exceptionally sharp bends, which cannot be achieved with waveguides and other technologies based on refraction. MPL and SVPCs open new routes to integrated photonics and opto-electronic circuits.

Photonic components responsive to external optical stimuli are attracting increasing interest, because their properties can be manipulated by light with fast switching times, high spatial definition, and potentially remote control. These aspects can be further enhanced by novel architectures, which have been recently enabled by the availability of 3D printing and additive manufacturing technologies. However, current methods are still limited to passive optical materials, whereas photo-responsive materials would require the development of 3D printing techniques able to preserve the optical properties of photoactive compounds and to achieve high spatial resolution to precisely control the propagation of light. Also, optical losses in 3D printed materials are an issue to be addressed. Here we report on advanced additive manufacturing technologies, specifically designed to embed photo-responsive compounds in 3D optical devices. The properties of 3D printed devices can be controlled by external UV and visible light beams, with characteristic switching times in the range 1-10 s.

The demand for disposable optics, especially in biomedical fields involving point of care testing systems has led to navigation for new low-cost and high quality optics fabrication processes. We demonstrate that 3D-printing of optics allows on-demand fabrication of polymer lenses at a low price, when no expensive initial tooling expenses are required. However, achieving high surface quality imaging optics has been challenging primarily when the lens diameter is greater than fivefold of a millimeter. In this work, we demonstrate an imaging quality 3D-printed polymer lens with high surface quality of RMS = 0.92 ± 0.33 nm (δ, N=25) and surface profile deviation of ± 500 nm within 0.5 inch aperture diameter. The 3D-printing method is based on Luxexcel’s Printoptical® Technology, using modified ink-jet printheads, by depositing micro-droplets of Opticlear, which is a UV-curable polymer with an inhomogeneity index of 1.1-1.3×10^-5 for 0.5 mm plate. We demonstrate a spatial resolution limit below 5 μm using a USAF1951-1x imaging resolution target for the 3D-printed singlet lens that is comparable to an off-the shelf commercial LA1509 N-BK7 plano-convex lens with the same specification parameters. Another application area of the inch-scale printed lens is in low-cost DSLR cameras. Experimental photos taken with a 3D-printed singlet lens and a commercial glass lens are nearly identical. As a result, manufacturing of 3D-printed singlet lenses with repeatability of ±200 nm for small or medium volume production at once becomes feasible by placing the printheads in parallel. We expect further developments towards achromatic optics by development of new 3D-printable polymers.

Additive Manufacturing (AM) is full of opportunities when it comes to fabrication of optical elements whether it be manufacturing complex design systems or precise fabrication of micro structures. In addition, there exists the possibility of introducing optical properties of interest (e.g. photoluminescence) or altering already existing properties (e.g. refractive index) of elements, with the corresponding alteration of raw materials used for fabrication. This possibility is being explored in our research group, to produce optical elements that can be ‘activated’ with respect to a specific property. Our current focus is on the introduction of narrow spectrum photo-luminescence of different wavelengths emitted simultaneously from a single 3D sample. Previously, we demonstrated the use of a photopolymer matrix embedded with quantum dots capable of emission in a specific wavelength, as the raw material to fabricate monolithic samples using DLP based 3D printing system. In this paper, we present the first 3D printed model that includes four different quantum dots in different spatial locations within the sample (printed with multiple quantum dot mixtures), capable of generating photoluminescence simultaneously in four different wavelengths in response to ultra violet excitation. Analysis was done to investigate the effect of nanocomposite mixture variations, printing, and photoluminescence from the samples, in terms of wavelength and emission intensity. The nanocomposites used for manufacturing the prototype were synthesized with a unique hydrophobic resin matrix (ORMOCER®) embedded with quantum dot nanoparticles.

Organometallic iridium(III) complexes have seen widespread use over the past two decades, particularly as phosphorescent dopants in organic light emitting diodes (OLEDs) due to their large spin-orbit coupling and metal-toligand charge transfer (MLCT) excited states. Interest in the non-linear optical (NLO) applications of these materials has increased recently with reports of both two-photon absorption (2PA) and reverse saturable absorption (RSA). A family of materials of the form [Ir^III(NO₂piq)₂(acac)] were synthesized and characterized, where acac is acetylacetonate and NO₂piq is a nitrophenylisoquinoline ligand. In order to assess structure-property relationships for the photophysics of these complexes, the placement of the nitro group was altered on the phenyl ring. Systematic control over the maxima of the absorption and photoluminescence bands attributed to the MLCT excited states was achieved through the ligand variation. The photophysical properties of this family of materials are discussed in detail and include their linear absorption spectra, photoluminescence measurements at 298 and 77K, excited state lifetimes, and CIE color chromaticity coordinates.

Here we present two techniques, which have advantages in the perovskite single crystal devices. First, we demonstrate modulation-doped layer growth and double heterostructure using a millimeter-sized hybrid halide perovskite crystal as a substrate. We show that previously known limiting factor of halide ion inter-diffusion can be constrained to few microns by (1) using low halide composition gradient and (2) adjusting solution concentrations just above the critical super saturation. In the solvo-thermal growth process, our layer growth time could be conveniently extended as necessary to grow a uniform layer, with only ~5 µm inter-diffusion region. This is a significant improvement compared to few seconds dipping time previously reported for a rapid ion exchange process without any layer growth. The growth of CH3NH3PbBr3 layer on top of CH3NH3Pb(Br0.85Cl0.15)3 bulk substrate is studied for different growth times to obtain up to 30µm layer thickness. Ion diffusion profile, layer thickness and crystallographic orientation have been characterized by cross sectional characterization using Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDS), and Electron Back-Scattering Diffraction (EBSD) . With this advancement, we are able to grow two consecutive perovskite layers to create a double heterostructure for the first time. Second, we demonstrate an as-grown milliliter-sized perovskite bulk crystal light emitting device. This device can be easily lighten up at low voltage (6-20 V) and at slightly low temperatures than room temperature (160-230 K). We are aiming to integrate both technologies with further optimization to produce efficient, pure-color perovskite light emitting devices for entire visible spectrum with low-cost and simple infrastructure.

Purified DNA was blended with hexadecyltrimethylammonium chloride (CTMA) in a 50/50 ratio to form DNA-CTMA. Next, 8 wt% silver (Ag) nanoparticles of ~1 micron diameter was blended with a 10/90 ratio of DNA-CTMA/butanol to form the nanocomposite solution. The solution was then cast in a Teflon dish to dry, forming an 80/20 Ag/DNA-CTMA nanocomposite thin film. The thickness of the samples measured 650 microns and were very flexible. EMI shielding effectiveness versus frequency measurements were then made using an Agilent E8362A performance network analyzer, calibrated for a frequency range of 8.2 GHz to 12.4 GHz using an Agilent X11644 mechanical calibration kit. Shielding effectiveness was found to be about -80 dB over the frequency range from 8 GHz to 12 GHz. Ag/DNA-CTMA nanocomposites have proven to provide excellent EMI shielding and are a promising alternative to existing EMI shielding materials. They have the potential to simply be painted on and Ag/DNA-CTMA EMI shielding requires no grounding.

In the last decade an important interest for green materials is observed. This interest is due either to the pollution caused by the organic plastic materials on one hand and to the interest for using natural products with new properties. Chromophores (dyes) are used in almost all fields of our life and activity: food, construction, textiles, automotives, photonics, etc. The presently developed optoelectronic materials exploit molecules with a large pi electron conjugation, which provides them an enhanced nonlinear optical response. This kind of molecules can be found also in many natural products. Their color is provided by the absorption of pi electrons. We have studied several types of extracts we obtained from spices made of molecules with a large pi electron conjugation in view of their application in photonics The extracts were then used to dope a well known biopolymer: DNA, giving in this way natural photoresponsive complexes. The obtained materials were processed into good optical quality thin films by spin coating technique, which we characterized for their spectroscopic, room temperature and high intensity laser pulses resistance. An enhanced fluorescence, low degradation kinetics and high optical damage thresholds were observed. All results obtained results obtained in this study will be presented and discussed. They are promising and suggest that in the near future we will be able to obtain functional, fully green materials for application in photonics. Acknowledgement This work was supported by a grant of Ministry of Research and Innovation, CNCS - UEFISCDI, project number PN-III-P4-ID-PCE-2016-0674, within PNCDI III.

Vapor coating methods allow for rough and/or fragile substrates to be nondestructively coated with a variety of polymer films. To date, various off-the-shelf garments, commercial textiles, threads/yarns, plant leaves, flower petals, porous membranes, and micropatterned Si/SiO2 substrates have been conformally coated with either electronic-polymer or polyacrylate films. Selected technologies created using vapor-coated fibers, textile and plant matter will be described, including touch-sensitive textiles for interactive electronics; smart elbow braces for movement sensing; textile triboelectric generators that convert small body motions into stored energy; wear-, wash- and ironing-resistant conductive cloths that generate heat with a small applied voltage; thread/yarn supercapacitors that can be sewed or knitted into garments for wearable and portable energy storage; and flexible electrodes for bioimpedance spectroscopy.

Interlacing is commonly used in textile industries producing multi-filament yarn. The post processing of this yarn for the fabric production, such as weaving and knitting, requires the yarn to possess some periodic cohesion points, otherwise it would separate and break. In an interlacer, a continuous jet of compressed air impinges on a running yarn and the interaction of the yarn with the swirling air intermingles periodically the filaments of the yarn creating the desired entanglement regions, also called knots. A regular distance between knots is required to guarantee a homogeneous appearance of the final fabric. However, textile industries report an irregularity in the interlaced yarn: not-interlaced segments occur without a clear reason. Hence, industries are interested in monitoring on-line the process, in order to check and improve its regularity. A high speed imaging analysis of the yarn motion in an interlacer allowed us to better understand the process dynamics and we found out that the interaction of the yarn with the air vortexes plays a key role. In addition, we developed, tested and optimized an on-line cheap sensing technique using a photodiode, that allows to monitor the yarn regularity during the production at high yarn speed (2000 m/min). We evaluated also the stability of the sensor, employing it in an industrial environment. Initially, we performed an average analysis of the interlacing frequency considering some meters of yarn at a time, then we moved towards a punctual analysis, to evaluate the regularity, the strength and the shape of each knot.

Waveguides with Bragg gratings realized on a flat polymer foil are promising candidates for advanced strain sensors since such a planar approach allows precise positioning of multiple sensors in various well-defined directions, in the same foil. As such, an optical version of an electrical strain gage can be realized. Herein, several parameters are discussed which define the behaviour of such sensor foils, in particular the grating design, including the wavelength of operation and mechanical and optical properties of the used polymers. Epoxy and Ormocer®-based Bragg grating sensors operating at 850 nm and 1550 nm wavelength were realized using nano-imprint lithography and laser direct-write lithography and their strain and temperature sensitivities were compared. Finally, it is demonstrated that optical strain gage rosettes can be realized by multiplexing 3 angularly displaced sensors in the same waveguide on a single foil.

Electro-optic (EO) polymers have been extensively considered as promising organic materials providing adjustable EO coefficient according to their designs. In addition, EO polymers comprehensively show well compatibility toward other optical components. However, thermal resistance of organic EO polymers still remains challenging for a range of application. To overcome this issue, we have selected norbornene-dicarboximide (NDI) to be utilized as based backbone for our EO polymer. This is because NDI polymer showed excellent properties toward EO applications, such as high glass transitional temperature and good optical transparency. Therefore, by attaching distinct EO chromophores to NDI backbone, both effective EO coefficient and thermal stable EO polymer could be adequately modified. In this study, the polymerisation was performed by ring opening metathesis polymerisation (ROMP). Grubbs catalyst was used to mildly initiate propagation. As the main NDI derivative was linked to cyclohexyl as it offers high thermal properties, NDI with phenyl vinylene thiophene (FTC) chromophore pendant was necessarily investigated to accomplish high chromophore loading density. Moreover, several conditions were considerably performed to afford polymer in high yield and excellent characteristics without unexpected side-reactions. Preliminary results showed that the obtained EO polymer prepared by ROMP at room temperature showed high chromophore loading density over 30% and yield more than 80%. Further investigations remain to be discussed to afford appropriate quality EO polymer for device fabrication.

It is well known in the literature that for a two photon nonlinear absorbing dye to be the most effective, high concentrations are needed. The problem is that most photophysical studies in solution are done at low concentration and in a solution. These low concentration studies are important for understanding inherent materials properties but it is also important to understand what happens in a material at high concentration. In addition to this, efforts have been made to study the effects of incorporating a dye into a solid matrix environment to better understand the constraints this environment has to a given material. Preliminary results for an epoxy system reveal the formation of excimers (excited state dimers) with an increase in concentration. Excimers are forming from the triplet excited state of the E1-BTF. A rate constant for this formation is 2.6 × 10⁵ M^-1 s^-1. While rather slow, at greater than 50 mM concentration the excimer is readily formed with <90% efficiency. This must be considered when making nonlinear absorption measurements since the excimer will certainly contribute to the overall nonlinearity.

We demonstrate an efficient ENZ response in the visible spectral range using organic molecular ultrathin films possessing a Lorentz-type dispersion. For this purpose, two polymethine dyes: sodium [5,6-dichloro-2-[[5,6-dichloro-1-ethyl-3-(4-sulphobutyl)- benzimidazol-2-ylidene]-propenyl]-1-ethyl-3-(4-sulphobutyl)-benzimidazolium hydroxide] (TDBC), and [2,4-bis[8-hydroxy-1,1,7,7-tetramethyljulolidin-9-yl]squaraine] (HTJSq) were used in spin-coated polymer films at different doping concentrations. By varying the doping concentration in thin films, the real part of highly dispersive permittivity ε1 can be manipulated and tuned such that the spectral width of ENZ region -1 < ε1 <1 resides in the visible spectral range. These results are not only extremely relevant for applications requiring a custom-tailored ENZ region in the visible but also provide important novel information on how molecular aggregation affects the ENZ properties. In particular, based on our findings, we stress that J-aggregate is not always a mandatory molecular assembly for obtaining a strong ENZ response. Instead, molecular aggregates with the size of a few nanometers resulting in strong molecular interactions (i.e. Davydov splitting of the lowest transition in energy) are required to achieve a strong ENZ response. The ENZ-enhanced optical Kerr nonlinearity is then investigated in the optimum concentration films of TDBC and HTJSq. Both nonlinear refractive index and nonlinear absorption coefficient are found to be strongly enhanced in the ENZ region originating from the coupling of excitonic transition dipoles associated with large molecular aggregates.

Methylammonium lead iodide (CH3NH3PbI3 or MAPI) is an organohalide lead perovskite, a promising material for optoelectronic application, e.g. in solar cells and photodetectors. It has a number of advantages over more traditional photovoltaics materials such as CIGS, GaAs, and even silicon due to facile solution processing, direct bandgap, high optical absorption, sufficiently high, balanced carrier mobilities, shallow trap defects and low-cost synthesis. At present moment there are number of article which reported measurement of second-harmonic generation in MAPI single crystals and presented contradictory results demonstrating the presence or absence of second-harmonic signal from MAPI. In this work, the second-harmonic generation (SHG) is observed in MAPI thin film that can be used as a base of high efficient solar sell. The SHG intensity from MAPI is measured to be at least three orders of magnitude more than one from substrate and encapsulation glasses. The MAPI nonlinear second-order susceptibility is estimated as compared to reference sample of y-cut quartz. In case of bulk contribution, the MAPI second-order susceptibility of 10-15 m/V is achieved. The polarization of SHG signal is experimentally studied in MAPI samples. The fraction of linearly polarized SHG signal is different for p- and s-polarization of fundamental wave and increases in case of p-polarized pump. The large non-polarized background of SHG signal is partly corresponded to SHG hyper-Rayleigh scattering. The hyper-Rayleigh scattering angle is experimentally estimated using the diaphragm behind the collimating objective lens and found to be less then 11 degrees.

We have been developing optical adhesives and resins suitable for optical communication field for many years. So far, we have developed many optical adhesives and resins, such as adhesives for optical path coupling, high refractive index resins with 1.6 or more and so on. With recent progress of optical application technology, various kinds of optical materials which enable flexible optical control in various fields have been needed. Especially, higher refractive index resins have been attracted particular attention because the performance of optical devices, such as diffraction gratings, imaging sensors, LEDs and so on can be improved. We have been studying to realize characteristics that are difficult to realize with only organic materials by combining with inorganic filler. By applying the method, we also have been studying to increase the refractive index of the resin. In this paper, we report to realize photo-curable high refractive index resin with refractive index of 1.7 or more which has good optical transparency for near IR and visible wavelengths by mixing resins and inorganic nanofillers. Because the resin is composed of UV curable resins and inorganic nanofillers, it is also easy to obtain thin films with good optical characteristics by spin-coating and UV curing process. The high refractive index resin of 1.7 or more will become a promising one in various optical fields because of its good optical characteristics and easy processability.

The chemical and photophysical properties of metal dithiolene compounds have been studied since the 1960’s due to the noninnocent nature of the dithiolene ligands and their rich, reversible electrochemistry. This class of materials have been utilized as biomimetic catalysts, sensitizers for solar energy conversion, laser dyes, and non-linear optical materials thanks in part due to their large photostability. We synthesized a series of nickel (II) and gold (III) dithiolenes with different functional groups in the para positions of the benzene rings to study the structure-property relationships in comparison to those that are commercially available. We will present spectroelectrochemistry data, femtosecond transient difference absorption spectra, and Z-scans in an effort to quantify the ground and excited-state photophysical properties of these compounds.

The reversible photoisomerization and consequent molecular orientation of azobenzene dyes are observed when these compounds are irradiated by specific wavelengths. Due to these attractive properties, these organic dyes have been the subject of several studies, aiming applications in optics and photonics devices. In this work, we functionalized acrylate resins with a series of azobenzene dyes to fabricate optically active devices which are sculpted via multiphoton absorption polymerization (MAP). For the experiments reported here, the host resin consists in two acrylate monomers namely tris(2-hydroxyethyl)isocyanurate triacrylate and ethoxylated(6) trimethylolpropane triacrylate, combined in equal proportion. These monomers are then mixed to a variety of azobenzene dyes: Disperse Red 1, Disperse Red 13, Disperse Red 19 and Disperse Orange 03. These dyes were added in weight percentages ranging from 0.05 to 1 wt%. In our experiment, a small amount of dye also works as a photoinitiator to start the polymerization process. In this case, the dominant reaction usually involves the loss of a molecule of N2 followed by reactions with the monomers. However, the remaining dye is unaffected by the laser beam, maintaining its optical properties, as can be observed after the complete fabrication procedure. Using a dedicated system we evaluate the photoinduced birefringence of these structures. To observe the light transmission through the device, placed between crossed polarizer and analyzer, we used a 0.25-NA microscope objective and a CCD camera. Through the analysis of the birefringence time-evolution curves, we observed significant residual optical memory, essential feature for micro-optical storage devices.

We investigate bulk heterojunction organic photodetectors with unbalanced charge carrier mobilities in the active layer. We present an experimental example of an organic photodetector with external quantum efficiency exceeding 75% (at illumination 638 nm), and bandwidth over 1 MHz, utilizing a 50 nm thick active layer with electron mobility ≈ 10−4 −10−3 cm2/(Vs) and low hole mobility ≈ 5 × 10−7 cm2/(Vs). The presented drift-diffusion simulation of bulk heterojunction photodiodes with Langevin recombination indicates that the bandwidth of photodiode is approximately independent of the mobility of slower charge carriers in the blend. The negative effect of low mobility on the responsivity can be compensated by increasing the reverse bias. Our study shows that well performing organic photodetectors can be fabricated using organic semiconductors having too low mobility for photovoltaic applications. Moreover, when optimizing the bandwidth of bulk heterojunction photodetectors, attention should be focused on the semiconductor with higher mobility.

Lasing action in Random Lasers made of polymers is usually achieved with a spatially distributed feedback, where scattering elements are spread over the active medium as a whole, yet some studies have shown that positive feedback may be provided from diffuse reflections at a scattering surface. Even though the latter has been demonstrated in polymeric films, it has not been shown to occur in on-chip integrated microstructures. Thus, in this paper, we demonstrate lasing action in Rhodamine B-doped polymeric microstructures whose feedback is based on diffuse reflections at the structure sidewall surfaces. The microlasers, produced by means of two-photon polymerization, are polygon-shaped on-chip microstructures featuring good structural quality and low shrinkage. The active material is Rhodamine B, which is homogeneously distributed throughout the structures. By pumping the structures with a ps-laser at 532 nm, a multi-peak emission with no evident spectral periodicity was observed. The peaks are a result of successive diffuse reflections of light at the structure sidewall surfaces that re-enters the gain medium and closes feedback loops with different perimeters and Q-factors. In spite of their omnidirectional emission, the microstructures lasing threshold was found to be on the order of nanojoules, which is comparable to what had been reported for microlasers based on optical resonators. This work therefore provides an easy way of realizing low-threshold random microlasers that hold potential as a solid-state laser source for integrated optics applications

A plethora of various colour TADF emitters was reported during the recent years. However, only few deep blue emitters possessing good colour purity as well as relevant stability were introduced [1-3]. For efficient TADF to take place, the occurrence of strong charge transfer is required. In turn, charge transfer demands the presence of fairly strong donor and acceptor units, which usually have a rigid molecular skeleton. However, the involvement of strong chromophores is known to lower the values of 1CT and 3LE states, which makes it difficult to obtain deep blue emission, even though vanishing ∆EST can be reached. Therefore, in order to design a deep blue TADF emitter, more flexible units have to be involved. Hence, in this work we show how by manipulation of the rigidity of the donor unit it is possible to find the trade-off between the properties of deep blue TADF emitters. Thus, here we present four derivatives of 9,9-dimethylthioxanthene-S,S-dioxide featuring 10,11-dihydro-5H-dibenz[b,f]azepine and diphenylamine donors attached in different fashion. Thorough photophysical investigation is provided. Theoretical approach is involved for better understanding of the observed results. [1] J. Mater. Chem. C 2014, 2 (3), 421–424. [2] Chem. Mater. 2015, 27 (19), 6675–6681. [3] Chem. Mater. 2017, 29 (21), 9154–9161.

The charge carrier mobility is an important parameter to characterize the performance of organic semiconductors based optoelectronic devices. In a given organic semiconductor, the mobility is often calculated based on the space-charge-limited (SCL) current measurement by fitting the corresponding current-voltage (J-V) data with a range of available space-charge-limited transport models to achieve the best fit, however, the accuracy of extracted mobility parameter relies on the correctness of model being used. Here, we present a fractional-dimensional SCL transport model for organic semiconductors with spatial disorder based on the fractional-dimensional calculus approach. We show that the thickness scaling of the SCL current is related to the spatial disorder in organic devices. The fractional-dimensional SCL transport model agrees well with the measured current density of several organic diode devices. The reported model is able to extract mobility values in organic devices with better accuracy as compared to existing models in the literature.

Semiconducting quantum dots (QDs) have unique optical properties such as high quantum yields and broad emission spectral wavelengths that are tunable by the quantum confinement effect. Considerable effort directed at modifying the surface of QDs using capping agents have led to a simple solution-based process, the stabilization of QDs, and their uniform dispersion in solvent. Due to these unique properties, quantum dots are of increasing importance in the fundamental studies and in a wide range of technological applications such as optical power limiters, light emitting devices, photovoltaics, lasers, and fluorescent labels for bioimaging. Tacking the full potential of QDs in optoelectronic devices require efficient mechanisms for transfer of energy or electrons produced in the optically excited QDs. We have investigated various organic-inorganic hybrids based on QD-decorated and QD-coupled systems on semiconducting substrates or molecules to achieve energy or charge transfer. The hybridization of p-type π-conjugated molecules to the surface of n-type QDs can induce distinct luminescence and charge transport characteristics due to energy and/or charge transfer effects. These kinds of energy/charge transporting properties are also observable in the perovskite QDs. The novel properties of hybrids consisting of QDs decorated or attached to conducting materials could find applications in molecular electronics and optoelectronics, including luminescent displays and energy harvesting cells.

Grayscale lithography is an important process for structuring polymeric materials for many applications in microsystem engineering. However, until now grayscale lithography is mostly used for patterning structures of the same height and remains largely unsuitable for generating more complex surfaces. Here, we present a novel method which enhances the accessible height ranges and surface topographies from one to a total of three discrete structure heights which can be accessed independently. This allows generating microstructures for, e.g., microfluidics and microoptics, with significantly enhanced structural complexity. The method does not require complex preprocessing steps. It is based on the varying absorption parameters of wavelength-selective absorbers mixed into a photocurable material. While the actual photoinitiator used covers all spectra, the absorbers are wavelength-dependent. These absorbers are chosen such that they absorb light in a narrow wavelengths regime while affecting the other processing wavelengths significantly less. We designed a photoresist with three distinct wavelengths: 365 nm, 415 nm, and 440 nm using polyethylene glycol diacrylate (PEGDA) as main resin material. Microfluidic channel structures were fabricated by transferring the generated structure into polydimethylsiloxane (PDMS).

We present plasmonics-enhanced organic solar cells (OSCs) containing nanostructures of plasmonic metals in the hole transport layer extending to the active layer of the solar cell. Finite-difference time-domain (FDTD) modeling was employed to simulate the interaction of incident light with the plasmonic nanostructures, leading to a broadband absorption enhancement in the OSCs. We studied the effect of employing nanostructures of different sizes and materials on the absorption enhancement in the OSCs. In some OSCs, we demonstrate 32% increase in the short circuit current density due to the presence of plasmonic nanostructures.

In our previous study, we demonstrated that a surface supported rapid evaporation crystallization (SSREC) method can be utilized to effectively prepare single nanometer nanocrystals (NCs) of 4-N, N-dimethylamino-4’-N’-methylstilbazolium tosylate (DAST), a bench mark of organic nonlinear optical (NLO) crystal. In this study, first, we extend the SSREC method to DAST single crystal nanowires (NWs) preparation by using a polymer-type surfactant. With one-drop of DAST-methanol solution, millimeter-scale the DAST NWs can be attained within one minute. We presume that this highly efficient driving forces of the fast self-assembling process originate from Coulombic interactions of the DAST nanocrystals. In order to further increase the crystal quality of the NWs, we propose a one-drop self-assembly process which separates the SSREC self-assembling process into two steps: SSREC process for NCs preparation and static cultivation process for NWs self-assembly. By this method, we successfully attain 4-N, N-dimethylamino-4'-N'-methylstilbazolium 2-naphthalenesulfonate (DSNS-2) NWs. The obtained DSNS-2 NWs have very high surface quality with surface roughness <150 pm, which is highly beneficial for fabricating integrated optical devices. Furthermore, the onedrop self-assembly method only requires reagents in microgram quantities, and thus this method is extremely environment-friendly.

Coupling of light to surface plasmons at metal cathode represents a significant light loss in organic light-emitting diode. The newly discovered graded photonic super-crystals with dual periodicity and dual basis, present great opportunity to improve the light out-coupling (The light extraction efficiency) from organic light-emitting diodes. These graded photonic super-crystals can be holographically fabricated by eight beam interference lithography. In this paper, we have computed, through electrodynamic simulation, the light extraction efficiency of planar, organic light-emitting diodes where the Al cathode is patterned with the graded photonic super-crystals. When the cathode of an organic light-emitting device is patterned in the graded photonic super-crystals, a light extraction efficiency up to 70% in the visible range can be achieved.

It is known that polarization holography uses photoanisotropic materials to record the state of light polarization. The polarization-holographic method of storage, transformation, transmission and processing of information is one of the most promising directions not only in optical but also in general among information technologies. The potential of increasing sensitivity of certain types of materials to light polarization is not yet fully mastered. In this paper, azodyecontaining photoanisotropic polymers are represented as a result of the study of polarization-sensitive materials, which are distinguished from their predecessors by outstanding photosensitivity. The report shows results of improving the foreground photoanisotropic characteristics, such as: increasing the degree of light-inducible birefringence and the rate of acceleration of this process. Which is the main measuring criterion of photosensitivity and effectiveness of the studied materials. The efficiency of azodye based polarization-sensitive materials is based on integration of their components by forces of electrostatic interactions or covalent bonds. In our previous works we have repeatedly shown clearly all the advantages of the results achieved by the molecular electrostatic integration of the material components. The presented paper shows different advantages of photoanisotropic materials consisting of alternative, covalent bonds, from which the increased velocity of photoanisotrophy and significantly improved magnitude of photosensitivity are worth noting on the first hand. Based on the experiences accumulated as a result of the conducted recent research and the developed recommendations, the new polarization-sensitive materials have deliberately been synthesized and studied.

In this paper, we introduce an alternative fabrication method to build a Polydimethylsiloxane (PDMS) waveguide system for bio-sensing applications. The sensor is based on the fact that the refractive index (RI) of PDMS can be manipulated by changing the ratio between the base and the curing agent, as well as the curing temperature. We further increase the RI difference between the core and cladding by adding a microstructure in the cladding. The microstructure is a periodic array of holes that can be filled with a liquid (each hole is 500 μm in diameter). The holes have the effect of decreasing the effective refractive index (eRI) of the cladding and thus helping the confinement of an electromagnetic wave in the core. As a fluid fill the holes the eRI of the cladding increases and thus the wave confinement is reduced.

Due to unique properties such as low vapor pressure and high ionic conductivity, room-temperature ionic liquids (RTILs) are very attractive not only for the chemical industry, but also for nano- and microstructures fabrication. The fabrication process conventionally involves usage of radiation sensitive polymer-based solutions (resists). We propose to replace those resists with eco-friendly solvent-free RTILs, which are polymerized by electron beam or UV light. Ionic liquids are also promising material for passive and active photonics components fabrication since their properties can be tuned in many ways by introducing special functionalities to the chemical structure of ions. In the present study, it is shown that different ionic liquids (with allyl or vinylbenzyl substituent) can be solidified on solid substrates (e.g. silicon or glass) by standard patterning lithography methods such as electron beam lithography in vacuum chamber and optical lithography with UV lamp. The thickness of the layer can be modified with ionic liquids mixture or by modified spin coating technique. By using patterning techniques, microstructures of different geometrical shapes are obtained from polymerizable RTILs containing fluorescein dianions. The shapes of obtained polymerized microstructures are also related to properties of the material including viscosities of selected ionic liquids. Various properties of polymerizable ionic liquids, such as thermal stability, viscosity, refractive index and light absorption can be adapted depending on the final application. Due to good optical properties, the fabricated microstructures can be used as photonic components, such as optical microresonators and waveguides.