Optics manufacturing technology is predicted to play a major role in the future production of integrated photonic circuits. One of the major drawbacks in the realization of photonic circuits is the damage of optical materials by intense laser pulses. Here, we report on the preparation of a series of organic–inorganic hybrid photoresists that exhibit enhanced laser-induced damage threshold. These photoresists showed to be candidates for the fabrication of micro-optical elements (MOEs) using three-dimensional multiphoton lithography. Moreover, they demonstrate pattern ability by nanoimprint lithography, making them suitable for future mass production of MOEs.

Microalgae are an ideal source for next-generation biofuels due to their high photosynthetic rate. However, a key process limitation in microalgal biofuel production is harvesting of biomass and extraction of lipids in a cost-effective manner. The harvesting of the algal biomass amounts to approximately 20 to 30% of the total cost of the cultivation; hence, developing an efficient and universal harvesting method will make the commercialization of microalgal bio-cultures sustainable. In this study, we developed, demonstrated, and evaluated a novel harvesting method based on Glass Reinforced Fiber Polymer (GFRP) panels, suitable for industrial-scale installations. The proposed method was based on previous observations of preferential micro-algae development on glass surfaces, as well as in the assumption that the microalgae cells would prefer to attach to and grow on substrates with a similar size as them. At first, we developed a laser micromachining protocol for removing the resin and revealing the glass fibers of the GFRP, available for algal adhesion, thus acting as a microalgae biomass harvesting center. Surface micromachining was realized using a ns pulsed ultraviolet laser emitting at 355 nm. This laser ensured high machining quality of the GFRP, because of its selective material ablation, precise energy deposition, and narrow heat affected zone. A specially built open pond system was used for the cultivation of the microalgae species Scenedesmus rubescens, which was suitable for biofuel production. The cultivation was used for the experimental evaluation of the proposed harvesting method. The cultivation duration was set to 16 days in order for the culture to operate at the exponential growth phase. The biomass maximum recovery due to microalgae attachment on the GFRP surface was 13.54 g/m2, a yield comparable to other studies in the literature. Furthermore, the GFRP surfaces could be upscaled to industrial dimensions and positioned in any geometry dictated by the photobioreactor design. In this study, the glass fiber reinforced polymer used was suitable for the adhesion of Scenedesmus rubescens due to its fiber thickness. Other microalgae species could be cultivated, adhere, and harvested using GFRP of different fiber sizes and/or with a modified laser treatment. These very encouraging results validated GFRPs’ harvesting capabilities as an attachment substrate for microalgae. Additional studies with more algae species will further strengthen the method.

Further advancements in organic light emitting diodes (OLEDs) using commercially available, low-cost materials is of high significance. Here, we report the application of commercially available chromophores as room temperature processed electron injection layers (EILs) in the conventional OLED architecture. The facile solution-processing of these chromophores, namely, 4‐dimethylamino‐4'‐nitrostilbene (DANS) and 1‐(4‐(dimethylamino)phenyl)‐6‐phenyl‐1,3,5‐hexatriene (DMA-DPH), along with the presence of nitrogen atom in their structure, which is expected to induce the formation of a negative interfacial dipole at the cathode interface, have motivated their use as EILs. Improved performance of the OLEDs using these chromophores was obtained. Especially, the OLED using DANS exhibited the highest luminous efficiency (LE), power efficiency (PE) and external quantum efficiency (EQE) values of 8.7 cd A-1, 6.75 lm W-1 and 2.9%, respectively, which represented a significant improvement compared to the reference device without the EIL (1.2 cd A-1, 0.7 lm W-1 and 0.4%, respectively). A variety of experimental and simulated results demonstrated that this enhancement is attributed to increased electron injection leading to balanced electron and hole currents, especially in the DANS embedding device. Additionally, we calculated significant broadening of the emission zone profile across the entire organic emitter in the devices using the chromophores, thus increasing the probability of radiative recombination and photon emission.

We report for the first time to our knowledge nanosecond laser welding of glass to aluminum using an industrial nanosecond IR fiber laser source with weld strength of 12.01 Nmm-2.

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