[IEEE 2019 IEEE 8th International Conference on Advanced Optoelectronics and Lasers (CAOL) - Sozopol, Bulgaria (2019.9.6-2019.9.8)] 2019 IEEE 8th International Conference on Advanced Optoelectronics and Lasers (CAOL) - Some Problems of Modeling the Shock Processes of Relaxed Optics

摘要： Transient interactions on conductive dielectric scatterers are analyzed by solving the Poggio–Miller–Chan–Harrington–Wu–Tsai (PMCHWT) surface integral equation with a marching on-in-time (MOT) scheme. The proposed scheme, unlike the previously developed ones, permits the analysis on scatterers with multiple volumes of different conductivity. This is achieved by maintaining an extra temporal convolution that only depends on permittivity and conductivity of these volumes. Its discretization and computation come at almost no additional cost and do not change the computational complexity of the resulting MOT solver. Accuracy and applicability of the MOT-PMCHWT solver are demonstrated by numerical examples.

Laser sintering of Cu@Ag core-shell nanoparticles for printed electronics applications

摘要： Bimetallic Cu@Ag core-shell nanoparticles (NPs) were synthesized by the reduction of copper 2-[2-(2-methoxyethoxy)ethoxy]acetate with hydrazine hydrate in benzyl alcohol followed by the reduction of silver ions on the copper surface using a galvanic replacement reaction. Ink consisting of the as-synthesized Cu@Ag NPs dispersed in a mixture of nontoxic solvents with different boiling temperatures (butanol and propylene glycol ethers) was prepared. Thin layers were spin coated on polyimide films using the developed ink. The conductive layer formed in air in the optimized conditions showed an electrical resistivity of 28.5 lX·cm.

Direct Observation of Crystal Engineering in Perovskite Solar Cells in a Moisture-Free Environment using Conductive Atomic Force Microscopy and Friction Force Microscopy

摘要： The origin of the increased efficiency of perovskite solar cells by control of environmental humidity was investigated using conductive atomic force microscopy (C-AFM) and friction force microscopy (FFM). The perovskite thin films fabricated in a humidity-free environment exhibited better crystallinity and lower number of trap sites than the films fabricated in a high-humidity environment. Through in-depth analysis using C-AFM and FFM, we found that there was locally decrystallized area in the perovskite structure fabricated in a high-humidity environment. By suppressing local decrystallization in a humidity-free environment, the power conversion efficiency (PCE) was increased by about 122%. This was mainly attributed to increase of the current density that elimination of the locally decrystallized area increase the effective active area. From this perspective, mapping local current and friction force using C-AFM and FFM could be new techniques for visualizing the effect of crystal engineering of perovskite solar cells in a humidity-free environment.

Enhancing fully printable mesoscopic perovskite solar cell performance using integrated metallic grids to improve carbon electrode conductivity

摘要： Carbon based Perovskite Solar cells (C-PSCs) have emerged as the most promising candidates for commercialisation in the field of perovskite photovoltaics, as they are highly stable, low cost and make use of easily scaled manufacturing techniques. However, the limited conductivity of the carbon electrode inhibits performance and represents a significant barrier to commercial application. Τhis work presents a scalable method for enhancing the carbon electrode conductivity through the integration of aluminium and copper grids into prefabricated C-PSCs. Adhered to the cells using an additional low temperature carbon ink, the metallic grids were found to dramatically reduce top electrode series resistance, leading to a large improvement in fill factor and efficiency. After grid integration, the 1 cm2 C-PSCs yielded power conversion efficiency (PCE) of 13.4% and 13% for copper and aluminium respectively, while standard C-PSCs obtained PCE of 11.3%. Performance is also significantly augmented in the case of larger-scale 11.7 cm2 modules, where PCEs went from 7.7% to 10% and 11% for aluminium and copper grids respectively. This technique offers a fast and low temperature route to high-performance, large-area C-PSCs and could therefore have serious potential for application to the high-volume manufacture of perovskite cells and modules.

Effect of purification on the electrical properties of transparent conductive films fabricated from single-walled carbon nanotubes

摘要： Transparent conductive films (TCFs) made of single-walled carbon nanotubes (SWCNTs) are usually fabricated using highly pure SWCNTs. Obtaining pure SWCNTs is an important step for harnessing their excellent electrical properties. Herein, we studied the effect of purification of SWCNTs by thermal and acid processes on the electrical properties of TCFs. These purification processes also affected the length and diameter of the SWCNT bundles. The purity of SWCNTs was determined by UV–visible-near-infrared spectroscopy and the metal content by thermogravimetric analysis. TCFs were made by spraying aqueous suspensions of SWCNTs having different purities onto polyethylene terephthalate substrates, and the ratios of dc to optical conductivities of the films were compared. Thermally purified (TP) SWCNT TCFs had a higher ratio than thermally and acid-purified (TAP) ones even though the purity of the TP-SWCNTs was lower than that of the TAP-SWCNTs. The conducting paths of the SWCNT bundle networks in the TP-SWCNT TCFs were well organized, because nanosized graphitic nanoparticles and metal catalysts occupied the spaces between the CNT bundles or networks without hindering the network connections. Although the SWCNT purity affected the conductivity of the SWCNT TCFs, the network property of lower junction resistance with smaller bundle diameter was more influential on film conductivity.

Full Solution-Processed Fabrication of Conductive Hybrid Paper Electrodes for Organic Optoelectronics

摘要： There is growing interest in the development of “green” electronics fabricated from “natural” materials, which could lead to renewable, sustainable and potential inexpensive organic optoelectronics. In this paper, a novel, facile and full-solution processed approach has been successfully demonstrated to fabricate a highly flexible and conductive paper electrode by electroless deposition with the dopamine molecules as an adhesion layer on the newly hybrid paper. The novel paper substrate was prepared through simple hot-press with commercial paper and polypropylene (PP) film. And it has smooth surface and improved mechanical property. Importantly, it is flexible and highly resistant to water, which was important for solution process. The obtained highly conductive paper exhibited smooth and hydrophobic surface with high reflection. In addition, these conductive papers also showed excellent mechanical flexibility and stability, indicating the strong adhesion between metal and hybrid paper, which facilitates the roll-to-roll process of the device. As a possible application, this paper electrode can be effectively used as a mechanical support and electrode in organic light-emitting diode (OLED), showing the potential possibility in future electronics.

Design of ultrathin OLEDs having oxide-based transparent electrodes and encapsulation with sub-mm bending radius

摘要： Highly flexible ultrathin organic light emitting diodes (OLEDs) hold vast potential as light sources particularly for wearable and imperceptible electronics. Most of the work demonstrated to date for highly flexible OLEDs, however, has relied on non-conventional transparent conductors such as conjugated polymers and has had no proper encapsulation or, if any, simple polymer-based encapsulation. We here demonstrate OLEDs that can be bent at a sub-mm radius even with conventional transparent conductive oxides (TCOs) and full encapsulation based on a multilayer gas barrier containing aluminum oxides, both of which are prone to strain-induced fracture. We realize such a small bending radius not only by adopting ultrathin substrates but also by exploiting the beneficial neutral plane shift toward the top of substrates identified in a system consisting of a ultrathin substrate and a multilayer device structure on its top. The proposed OLEDs exhibit stable performance after 1,000 bending iterations even at a bending radius far smaller than 1 mm and show similar reliability to that of glass-based reference devices even after two weeks in the acceleration test chamber.

An electrospun polymer composite with fullerene-multiwalled carbon nanotube exohedral complexes can act as memory device

摘要： Functional polymer nanocomposites with distinctive electrical properties made of nanocarbon structures and biodegradable polymers are promising materials for the development of flexible and eco-friendly smart systems. In this work, a novel electrospun conductive polymer nanocomposite made of polycaprolactone with an exohedral complex made of multiwalled carbon nanotubes and fullerene C60 was prepared and characterized. The preparation was straightforward and the complexes self-assembled within the nanocomposite fibers. The nanocomposite showed electrical switching behavior due to charge accumulation of fullerene C60 upon electrical stimulation. Write-once read-many memory devices were fabricated by electrospinning a nanocomposite with 0.8%wt. fullerene C60 onto interdigitated coplanar electrodes. The device retained the ON state for more than 60 days and could be thermally reset, reprogrammed and erased with subsequent electrical and thermal cycling. Moreover, the electrical resistance of the device could be modulated by applying different programming voltage amplitudes and programming times, which revealed its adaptive behavior and potential application to neuromorphic systems.

Ligand-Controlled DArP for n-Type and Ambipolar Mesopolymers

The mechanism of filament formation in Ag doped Ge–Se resistive switching cell

摘要： The AgGeSe2 solid state electrolyte has been studied in resistive switching. According to the I–V relationship, the possible mechanisms, including the SCLC (space-charge-limited current) model is applied to explain the result of experiments. The conductive filament formation is found to be related to the Schottky barrier between the electrode and electrolyte.