This PDF file contains the front matter associated with SPIE Proceedings Volume 9994 including the Title Page, Copyright information, Table of Contents, Introduction (if any), and Conference Committee listing.

In this talk, we will discuss recent progress in a range of solid-state devices, including organic light-emitting diodes (OLEDs), organic field-effect transistors (OFETs), sensors, organic solar cells, and photodetectors. We will present strategies to modify and stabilize the electronic properties of interfaces that can yield devices with improved performance and longer lifetime. Examples of recent studies to reduce the environmental footprint of this emerging technology will be provided. We will show that these advances can lead to disruptive innovations to address some of the world’s greatest challenges.

We propose ganglion cell receptive-field-type filters with the use of the photoreceptor protein bacteriorhodopsin. Visual image processing is possible with the use of only one sensing element. We also demonstrate that our difference of Gaussians (DOG) filter, which mimics on-center off-suround ganglion cell receptive fields, has the function of a Laplacian filter and can act as an edge detecor. The X-type receptive field responses obtained by the filter, for a variety of stimuli, are compared with available electrophysiological recodings.

The work reported outlines the synthesis, film formation and application of NIR-absorbing metal dithiolene and metal diimine molecules suitable for film formation with varying ligands and central metals. Formation of an electroactive film on conducting glass or mesoporous TiO₂ support can be achieved through electropolymerisation, electrodeposition, spin/drop coating or chemical attachment. In this context, we will outline the synthesis, characterisation and properties of a new family of NIR-absorbing aromatic metal diimine complexes. These complexes are shown to give rise to planar, delocalised structures with small HOMO-LUMO gaps, through the use of extended non-innocent ligands o-semibenzoquinonediimines. Herein we report the synthesis of a series of metal diimine complexes, modified to extend the electronic conjugation and shift the intense low-energy absorption from the visible to the NIR region. This study extends the range of available NIR absorping metal-complex chromophores and opens up new possibilities for wavelength tuning and application.

In the last decade a lot of interest was paid to DNA materials in view of their practical applications in photonics and in electronics. This aspect is especially due to the fact that this polymer is eco-friendly, originating from renewable resources and can be obtained from any animal or vegetable waste. In this respect many studies have shown that DNA is an intriguing biopolymer which can find applications in many fields. In this paper we will review and discuss the functionalization of DNA and some practical applications.

Several bacteria evolve in spore if the environmental conditions get to adverse e.g. for nutrient deprivation. The bacteria of genus Bacillus are Gram-positive aerobic bacteria and they are able to produce endospores (physiological inactive and resistant form), usually dispersed as aerosols. Endospores can survive for long time, until the conditions get back favourable. The genera Bacillus include pathogens, as Bacillus anthracis, used in the past as biological weapon. Prompt, accurate and sensitive detection is crucial for its control as pathogens or bioterrorism attacks. In case of the contamination with spores of B. anthracis, the time is essential to assure success in rescue. So, in this context, the early and fast analytical techniques, that need no or negligible sample preparation, is strongly required. Raman spectroscopy, and in particular Surface Enhanced Raman Spectroscopy (SERS), that can amplify nonlinearly the inherently weak Raman signal by several orders of magnitude, have become recognized and versatile analytical techniques also in microorganisms detection. These techniques can be used as sensitive tools for the detection and classification of biological threats, they can provide the chemical fingerprint of samples without complex and time-consuming pre-treatment samples preparation. Furthermore the development of in-field portable compact Raman platforms allows for using SERS for routine analysis. In the framework of the RAMBO (Rapid Air particle Monitoring against BiOlogical threats) project the feasibility of the SERS technique for the rapid identification and classification of few units of Bacillus spp (B. atrophaeus and B. thuringiensis) spores was investigated. B. atrophaeus and B. thuringiensis are harmless but genetically similar to the deadly B. anthracis. The RAMBO project purpose is the development of an advanced sensor with high performances, capable of detecting few spores or bacilli, with high selectivity and reliability, by means of two sensing techniques: SERS for early warning of bioagents dispersed in air or in water, and Polymerase Chain Reaction (PCR) technique for final recognition and validation. SERS and PCR will work in a microfluidic chip. In order to bind selectively the endospores, specific peptide receptors for B. thuringiensis have been selected to functionalize SERS substrates. To characterize the substrates, with and without spores to assess the effective immobilization of target, microscopy inspections, by optical microscope and Scanning Electron Microscope (SEM), were also carried out. The results show up the poor selectively of these peptides for B. thuringiensis, used as target, compared with the non specific Bacillus control. The performance of the system seems to be quite similar for both of them: the data processing by Principal Component Analysis and the following clustering analysis suggest the presence of indistinct answers for any bound endospore on the surface, and this is confirmed by microscope inspection. It could decrease the discrimination power of the sensor. Despite of such poor receptor selectivity, the SERS spectra of B. thuringiensis endospores show characteristic signals that can be related to DNA fragments or, much more probably, to the peptidoglycan (component of the external coat). This spectral feature could be used to detect the presence of B. thuringiensis endospores.

Organic materials that exhibit large real third-order optical nonlinearities, |Re(χ(3))|, and that also have low linear and nonlinear losses at telecommunication wavelengths may be useful for a range of all-optical signal-processing (AOSP) applications. Based on their solution linear and nonlinear optical characteristics, polymethine dyes in general, and chalcogenopyrylium-terminated heptamethines in particular, are a promising class of materials for AOSP, but the translation of their microscopic nonlinearity to device-relevant materials is hindered by significant aggregation of the molecules in high-chromophore density films.[1] An approach to minimize aggregation these dyes, in which bulky and rigidly out-of-plane groups are introduced both in the center of the polymethine bridge and on the heterocyclic end groups, has been developed and can lead to thin-film materials exhibiting combinations of large |Re(χ(3))|, large two-photon figure-of-merit, and low linear loss that are suitable for AOSP.[2] [1] Hales J. M., Matichak J., Barlow S., Ohira S., Yesudas K., Brédas J.-L., Perry J. W. and S. R. Marder, Science, 2010, 327, 1485. [2] Barlow S., Brédas J.-L., Getmanenko Y. A., Gieseking R. L., Hales J.M., Kim H., Marder S.R., Perry J. W., Risko C., Zhang Y., Materials Horizons, 2014, 1, 17.

In combination with optical cavities, organic semiconductor crystals are powerful candidates for current-injected organic laser devices. For such cavities diffraction gratings are applicable. In common with external diffraction gratings made of dielectrics and oxides, built-in ones are effective for producing narrow linewidth emissions. However, direct fabrication of the diffraction gratings on the surfaces of the organic crystals is still challenging. In the present studies, we directly engraved one-dimensional (1D) diffraction gratings on the flat surfaces of organic semiconductor crystals by using focused ion beam (FIB) lithography, and shaped a distributed feedback resonator (DFB) structure. We chose as the organic semiconductor material 5,5'''''-diphenyl-2,2':5',2'':5'',2''':5''',2'''':5'''',2'''''-sexithiophene (P6T) from among thiophene/phenylene co-oligomers. We grew plate-like crystals of P6T in a vapor phase. The P6T crystals showed emissions with a maximum intensity around 630 nm. We laminated them on Si wafer substrates covered with 300-nm-thick silicon dioxide and 160-nm-thick Al-doped ZnO (AZO) layers. The AZO layer was used to prevent the crystals from being charged during the FIB lithography. We precisely controlled FIB process conditions and obtained the gratings having the equally-spaced 200 (400) grooves with the periods of 240 (200) nm. When we observed the emissions perpendicular to the grating grooves as well as parallel to the crystal surface under ultraviolet light from a mercury lamp, these crystals with the 1D diffraction gratings indicated narrowed emission peaks at 745 (670) nm. From the grating period and the emission peak position, we estimated an order of diffraction and an effective refractive index. We related the effective refractive index with a phase refractive index of the crystal and decided the optimum grating period to be 190 nm to produce the narrowed peak at 630 nm. We fabricated the diffraction grating having the optimum grating period on the P6T crystal by engraving 400 grooves, and succeeded in observing strong single peak at 629 nm. Using the present method, we can design the diffraction grating periods for the optical devices of organic oligomer crystals that show the narrow linewidth emissions.

Our recent research involves the design, characterization and testing of devices constituting low bandgap conjugated polymers, surface-engineered quantum dots (QDs), carbon nanotube (CNT)-QDs, QDs decorated nanowires, and QD coupled conjugated polymers. The resulting hybrid materials can be used for facilitating the charge/energy transfer and enhancing the charge carrier mobility in highly efficient optoelectronic and photonic devices. Exploiting the full potential of quantum dots (QDs) in optoelectronic devices require efficient mechanisms for transfer of energy or electrons produced in the optically excited QDs. We propose semiconducting π-conjugated molecules as ligands 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. QDs and π-conjugated molecule hybrids with controlled luminescent properties can be used for new active materials for light-emitting diodes and flexible displays. In addition, such hybrid systems with enhanced charge transfer efficiency can be used for nanoscale photovoltaic devices. We have also explored single nanoparticle based electronics using QDs and π-conjugated molecule hybrids with molecular-scale n–p or n-insulating (ins)–p-heterojunction structures.

The results of calculation of nitrogen vacancy geometry in GaN/AlN heterointerface and its comparison with experimental data are discussed in the paper. The methods of calculation of point defects geometry in the GaN/AlN interface within the frameworks of self-consistent field and density functional theory are compared.

In order to find eco-friendly materials for different applications an important research effort was devoted to the materials science in the last decade. A particular attention attracted the deoxyribonucleic acid (DNA). The interest is due to its versatility, biodegradability, abundance and their origin from renewable sources. DNA based new materials, functionalized with hexadecyltrimethylammonium chloride (CTMA) and aromatic compounds were prepared. Solutions with two different concentrations of aromatic compounds were obtained in butanol. The obtained, new complexes were processed into good optical quality thin films by spin coating method. Films were deposited on glass substrates and characterized for their spectroscopic, linear and nonlinear optical properties. The third-order nonlinear optical (NLO) properties of thin films were determined by the optical third-harmonic generation technique at 1 064.2 nm fundamental wavelength. The obtained materials, with improved fluorescence efficiency, present a potential interest for application in photonics.

The technology of Fiber Bragg grating (FBG) belongs to the most widespread fiber-optic sensors. They are used for measuring a large number of physical and chemical quantities. Small size, immunity to electromagnetic interference, high sensitivity and a principle of information encoding about the measurement value into spectral characteristics causes usability of FBG sensors in medicine for monitoring vital signs such as temperature, blood pressure, pulse, and respiration. An important factor is the use of an inert material for the encapsulation of Bragg gratings in this area. A suitable choice is a polydimethylsiloxane (PDMS) elastomer having excellent thermal and elastic properties. Experimental results describe the creation of FBG sensory prototype for monitoring breathing in this paper. The sensor is realized by encapsulation of Bragg grating into PDMS. The FBG sensor is mounted on the elastic contact strap which encircles the chest of the patient. This tension leads to a spectral shift of the reflected light from the FBG. For measurement, we used a broadband light source Light-Emitting Diode (LED) with central wavelength 1550 nm and optical spectrum analyzer.

The paper describes the use of fiber-optic interferometer as a security sensor, which was built in a prototype of a plastic window. Its primary function is detecting the vibration and acoustic impulses, which affect the transparent glass part of the window prototype. The presented results are focused on the analysis of the frequency characteristic of the created prototype to verify of the sensitivity of the sensor. The knowledge of the frequency characteristic of the proposed window sensor is necessary due to the correct interpretation of the measured data. The interferometer is a Mach-Zehnder type and operates with an optical fibers G.652.D. As a radiation source, we used DFB laser with the wavelength of 1550 nm. The input optical power is 1 mW. Optical signal was detected by PbSe photodetector. The generator of the harmonic signal with fixed amplitude of the signal and digital sound level meter were used to the analysis of the frequency characteristic of the prototype. The analyzed frequency spectrum was in a range of 35 Hz to 8 kHz. The paper showed that this system is suitable for measurements of vibration impulses and acoustic waves in the audible range from 40 Hz up to 3 kHz.

Fiber-optic sensors are one of the dynamically developing areas of photonics and photonic applications. This group of sensors can also include fiber-optic interferometers which enable very sensitive sensing. They are entirely passive regarding power supply, and immune to electromagnetic interference. This type of sensor is dependent on the phase change. It mostly used in the field which requires high measurement accuracy. We can achieve a change of sensitivity in the order of 10-8. The fundamental problem of fiber-optic interferometry is a design and imposition (encapsulation) of the measuring arm and reference arm of the interferometer. Polydimethylsiloxane elastomer (PDMS) is one of the possibilities to encapsulation of the sensory arm. Two-component PDMS Sylgard 184 is used type. The article analyzes the effect of encapsulation into a PDMS of the measuring arm of the interferometer to frequency response and sensitivity of the Mach-Zehnder interferometer with the division of power in a ratio of 1:1 (measuring arm and reference arm). Input power set to a reference value of 1 mW, this value was constant for all performed experimental measurements. The generator of a harmonic signal with fixed amplitude signal used for analysis of the frequency characteristic of the interferometer. The application written in LabView development environment, evaluated the amplitude-frequency spectra of the signal. Repeated test of assembled prototype verified the measured results.