Poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS) thin films on indium tin oxide and glass substrates have been fabricated and subjected to a non-adiabatic annealing process. The films showed subtle changes in their structure and optical properties as well as an increase in conductivity due to the effects of rapid thermal annealing. Through a combination of Raman spectroscopy, X-ray photoelectron spectroscopy and atomic force microscopy studies in conjunction with electrical characterization, and four-point probe measurements, material enrichment of conductive PEDOT domains at the polymer-metal interface have been demonstrated, which well explains the surface conductivity improvement of a thin film of PEDOT:PSS after annealing.

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The conjugated polymer poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS) is subjected to non-adiabatic rapid thermal processing and exhibits an increase in conductivity through the film. Electrical measurements on an ITO/PEDOT:PSS/Al diode structure display a current-voltage relationship that correlates to space charge limited conduction with the presence of an exponential trap distribution, which is commonly seen in other organic media. With careful application of this current transport theory to the obtained experimental results, the root cause of the conductivity enhancement can be attributed solely to an increase in the charge mobility of carriers in the PEDOT:PSS film. In comparison to an untreated PEDOT:PSS film, processing at 200 °C for 30 s results in a 35% increase in carrier mobility to 0.0128 cm2 V−1 s−1. Values for other material characteristics of PEDOT:PSS can also be extracted from this electrical analysis, and additionally are found to be unchanged with processing. Hole concentration, effective density of states, and total trap density are found to be 7.4 × 1014 cm−3, 1.5 × 1018 cm−3, and 3.7 × 1017 cm−3, respectively.

Oligodeoxyribonucleotides (ODNs) that have four repeats of the human telomeric sequence d(TTAGGG)(n) can assume multiple monomolecular G-quadruplex topologies. These are determined by the cation species present, the bases at the 5' or 3' end, and the sample preparation technique. In this work, we report our studies of the concentration dependence of the circular dichroism (CD) and the vibrational modes probed by Raman scattering of three previously characterized monomolecular G-quadruplexes: H-Tel, d[5'-A(GGGTTA)(3)GGG-3']; hybrid-1, d[5'-AAA(GGGTTA)(3)GGGAA-3']; and hybrid-2, d[5'-TTA(GGGTTA)(3)GGGTT-3']. At high (millimolar) ODN concentrations, we observed a transformation of the CD spectrum of H-Tel, with a relaxation time on the order of 10 h. Analysis of the kinetics of this process is consistent with the formation of an aggregated complex of folded H-Tel monomers. Upon dilution, the aggregates dissociate rapidly, yielding spectra identical to those of monomeric H-Tel. Both hybrid sequences undergo a similar transition under high-salt (1 M) conditions. The measurements suggest that for these ODN concentrations, which are typically used in high-resolution spectroscopies, the monomolecular G-quadruplex structures undergo a transition to multimolecular structures at room temperature. Guided by our findings, we propose that the terminal bases of the hybrid-1 and hybrid-2 ODNs impede the formation of these aggregates; however, in solutions containing 1 M salt, the hybrid oligonucleotides aggregate.

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Spatial control of the conductivity of poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS) is demonstrated through the use of ultraviolet (UV) exposure. With appropriate UV exposure, electrical characterization shows that the in-plane sheet resistance of PEDOT:PSS films is increased by 4 orders of magnitude compared to unexposed regions. Characterization of the films using Raman spectroscopy identifies a significant reduction of the inter-ring stretching modes between PEDOT monomers and a morphological shift from the quinoid to benzoid form of PEDOT. Additional analysis using Fourier transform infrared spectroscopy indicates a reduction in film doping and a decrease in C═C vibrational modes that are associated with PEDOT oligomer length. Height and phase images of these films obtained from atomic force microscopy exhibit a loss of phase segregation in the film between the PEDOT grains and PSS regions. Spectroscopic ellipsometry highlights an increase in both the real and imaginary components of the index upon UV exposure. This broad range of analysis consistently suggests that the increased resistivity can be attributed to a significant reduction in material doping caused by scission-driven decomposition of the conductive PEDOT chains. When flood exposure is combined with the use of an appropriate UV blocking mask, patterning in the conductivity of PEDOT:PSS films can be realized. In contrast to other patterning approaches, no resist development or etching is required for the electrical isolation of certain regions. To demonstrate the efficacy of this process, an organic light emitting diode was fabricated with UV-patterned PEDOT:PSS as a hole transport layer. The regions of unexposed PEDOT:PSS produced electroluminescence, whereas those exposed to UV remained unlit, enabling the realization of pixelated illumination with no removal of material.

Rapid thermal annealing has been applied to poly(acrylic acid)-capped CdTe nanoparticles. This annealing process has shown to provide some control over the semiconductor core properties, while preserving the capping ligand intact. The photoluminescence and absorption properties of the nanoparticles remain nominally unchanged up to annealing temperatures of 400 °C and annealing durations of 30 s. This process was found to be an effective postsynthesis means of improving the crystallinity of the semiconductor core. The crystallinity enhancement is identified by solution-based Raman spectroscopy using a hollow-core photonic crystal fiber. This novel method of detecting a crystalline change in nanoparticles is corroborated by powder X-ray diffraction measurements and X-ray photoelectron spectroscopy.

Serial block face scanning electron microscopy (SBF‐SEM), also referred to as serial block‐face electron microscopy, is an advanced ultrastructural imaging technique that enables three‐dimensional visualization that provides largerx‐ and y‐axis ranges than other volumetric EM techniques. While SEM is first introduced in the 1930s, SBF‐SEM is developed as a novel method to resolve the 3D architecture of neuronal networks across large volumes with nanometer resolution by Denk and Horstmann in 2004. Here, the authors provide an accessible overview of the advantages and challenges associated with SBF‐SEM. Beyond this, the applications of SBF‐SEM in biochemical domains as well as potential future clinical applications are briefly reviewed. Finally, the alternative forms of artificial intelligence‐based segmentation which may contribute to devising a feasible workflow involving SBF‐SEM, are also considered.