The ultimate target of molecular electronics is to combine different types of functional molecules into integrated circuits, preferably through an autonomous self-assembly process. Charge transport through self-assembled monolayers has been investigated previously, but problems remain with reliability, stability and yield, preventing further progress in the integration of discrete molecular junctions. Here we present a technology to simultaneously fabricate over 20,000 molecular junctions-each consisting of a gold bottom electrode, a self-assembled alkanethiol monolayer, a conducting polymer layer and a gold top electrode-on a single 150-mm wafer. Their integration is demonstrated in strings where up to 200 junctions are connected in series with a yield of unity. The statistical analysis on these molecular junctions, for which the processing parameters were varied and the influence on the junction resistance was measured, allows for the tentative interpretation that the perpendicular electrical transport through these monolayer junctions is factorized.

We report a low-temperature colloidal synthesis of single-layer, five-atom-thick, β-In2Se3 nanosheets with lateral sizes tunable from ∼300 to ∼900 nm, using short aminonitriles (dicyandiamide or cyanamide) as shape controlling agents. The phase and the monolayer nature of the nanosheets were ascertained by analyzing the intensity ratio between two diffraction peaks from two-dimensional slabs of the various phases, determined by diffraction simulations. These findings were further backed-up by comparing and fitting the experimental X-ray diffraction pattern with Debye formula simulated patterns and with side-view high-resolution transmission electron microscopy imaging and simulation. The β-In2Se3 nanosheets were found to be indirect band gap semiconductors (Eg = 1.55 eV), and single nanosheet photodetectors demonstrated high photoresponsivity and fast response times.

In this work studies on photochromism for optics and photonics are reviewed. The versatility of organic chemistry gives photochromic materials wide opportunities for several applications that range from tunable filters and gratings, to refractive-index modulators for optical fibers and communications, to optical memories and sensors. Moreover, novel results on efficient modulation of amplified emission in a conjugated polymer/photochromic system are presented. Credit for the background image (WR 25 and Tr16-244, open cluster Trumpler 16): NASA, ESA and Jesús Maíz Apellániz

It is common knowledge that poly(3-hexylthiophene) (P3HT)/[6,6]-phenyl-C61-butyric acid methyl ester (PCBM) blend, a prototype system for bulk heterojunction (BHJ) solar cells, consists of a network of tens of nanometers-large donor-rich and acceptor-rich phases separated by extended finely intermixed border regions where PCBM diffuse into P3HT. Here we specifically address the photo-induced dynamics in a 10 nm thin P3HT/PCBM blend that consists of the intermixed region only. Using the multi-pass transient absorption technique (TrAMP) that enables us to perform ultra high sensitive measurements, we find that the primary process upon photoexcitation is ultrafast energy transfer from P3HT to PCBM. The expected charge separation due to hole transfer from PCBM to P3HT occurs in the 100 ps timescale. The derived picture is much different from the accepted view of ultra-fast electron transfer at the polymer/PCBM interface and provides new directions for the development of efficient devices.

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This paper presents a laboratory-scale experimental investigation of laser cleaning of diagnostic First Mirrors (FMs). Redeposition of contaminants sputtered from tokamak first wall onto FMs surface could dramatically decrease their reflectivity in an unacceptable way for the functioning of the plasma diagnostic systems. Laser cleaning is a promising solution to tackle this issue. In this work, pulsed laser deposition was exploited to produce rhodium films functional as FMs and to deposit onto them carbon contaminants with tailored features, resembling those found in tokamaks. The same laser system was also used to perform laser cleaning experiments by means of a sample handling procedure that allows to clean some cm 2 in few minutes. The cleaning effectiveness was evaluated in terms of specular reflectivity recovery and mirror surface integrity. The effect of different laser wavelengths (λ = 1064, 266 nm) on the cleaning process is also addressed.

We present gain and lasing results from a polyrotaxane consisting of a conjugated polymer (polyfluorene-alt-biphenylene) threaded through sugar macrocycles (β-cyclodextrin). Encapsulation suppresses interchain charge separation, leading to lasing emission not observed in the unthreaded polymer, and enlargement of the stimulated emission in threaded polymer is observed. We demonstrate all-optical switching distributed feedback laser.

The authors study laser dynamics in a polymer distributed feedback resonator by performing pump-probe experiments. They measured the population kinetics in the device under lasing operation with subpicosecond time resolution. By modeling the system with a set of coupled rate equations, which account for stimulated emission and nonradiative decays, they extract quantitative information on buildup time, photon lifetime, and pulse duration and give evidence of the feedback and loss mechanisms. They also investigate the influence of the grating length in the feedback and loss processes, and they show that lower pump energy thresholds can be achieved with short devices.