Effect of Solvent Exchange at the Biphasic Dip-Coating Interface on the Formation of Polythiophene Thin Films

The biphasic dip-coating method reduces the amount of solution required for coating by using a phase-separated biphasic solvent system and is highly promising for the preparation of large-area thin films with applications in electronic devices. We studied the effects of varying the miscibility of the low-lying secondary solvent and the high-lying polymer-dissolving solvent on polymer crystallization and on the resulting films. We systematically chose three kinds of solvents with high density for use as the low-lying solvent phase and compared the miscibilities of the low-lying solvents and the high-lying polymer solution in terms of their Hansen solubility parameters (HSPs). We demonstrated that the HSP distance is correlated with the degree of intermixing of the low-lying and high-lying solvents and determined the effects of intermixing on polymer aggregation and stability in the solution state for various aging times. The degree of solvent exchange at the interface also determines the film morphology and charge carrier mobility of the resulting dip-coated P3HT thin film. This study confirms the potential of biphasic dip-coating as a scalable film preparation method for use in large-area flexible electronics

Simultaneously Enhancing the Cohesion and Electrical Conductivity of PEDOT:PSS Conductive Polymer Films using DMSO Additives

Conductive polymer poly­(3,4-ethylene­dioxy­thiophene):­poly­(styrene­sulfonate) (PEDOT:PSS) has attracted significant attention as a hole transport and electrode layer that substitutes metal electrodes in flexible organic devices. However, its weak cohesion critically limits the reliable integration of PEDOT:PSS in flexible electronics, which highlights the importance of further investigation of the cohesion of PEDOT:PSS. Furthermore, the electrical conductivity of PEDOT:PSS is insufficient for high current-carrying devices such as organic photovoltaics (OPVs) and organic light emitting diodes (OLEDs). In this study, we improve the cohesion and electrical conductivity through adding dimethyl sulfoxide (DMSO), and we demonstrate the significant changes in the properties that are dependent on the wt % of DMSO. In particular, with the addition of 3 wt % DMSO, the maximum enhancements for cohesion and electrical conductivity are observed where the values increase by 470% and 6050%, respectively, due to the inter-PEDOT bridging mechanism. Furthermore, when OLED devices using the PEDOT:PSS films are fabricated using the 3 wt % DMSO, the display exhibits 18% increased current efficiency

Chitosan Oligosaccharide-Stabilized Ferrimagnetic Iron Oxide Nanocubes for Magnetically Modulated Cancer Hyperthermia

Magnetic nanoparticles have gained significant attention as a therapeutic agent for cancer treatment. Herein, we developed chitosan oligosaccharide-stabilized ferrimagnetic iron oxide nanocubes (Chito-FIONs) as an effective heat nanomediator for cancer hyperthermia. Dynamic light scattering and transmission electron microscopic analyses revealed that Chito-FIONs were composed of multiple 30-nm-sized FIONs encapsulated by a chitosan polymer shell. Multiple FIONs in an interior increased the total magnetic moments, which leads to localized accumulation under an applied magnetic field. Chito-FIONs also exhibited superior magnetic heating ability with a high specific loss power value (2614 W/g) compared with commercial superparamagnetic Feridex nanoparticles (83 W/g). The magnetically guided Chito-FIONs successfully eradicated target cancer cells through caspase-mediated apoptosis. Furthermore, Chito-FIONs showed excellent antitumor efficacy on an animal tumor model without any severe toxicity