A “Phase Separation” Molecular Design Strategy Towards Large‐Area 2D Molecular Crystals

2D molecular crystals (2DMCs) have attracted considerable attention because of their unique optoelectronic properties and potential applications. Taking advantage of the solution processability of organic semiconductors, solution self‐assembly is considered an effective way to grow large‐area 2DMCs. However, this route is largely blocked because a precise molecular design towards 2DMCs is missing and little is known about the relationship between 2D solution self‐assembly and molecular structure. A “phase separation” molecular design strategy towards 2DMCs is proposed and layer‐by‐layer growth of millimeter‐sized monolayer or few‐layer 2DMCs is realized. High‐performance organic phototransistors are constructed based on the 2DMCs with unprecedented photosensitivity (2.58 × 10⁷), high responsivity (1.91 × 10⁴ A W^?1), and high detectivity (4.93 × 10¹⁵ Jones). This “phase separation” molecular design strategy provides a guide for the design and synthesis of novel organic semiconductors that self‐assemble into large‐area 2DMCs for advanced organic (opto)electronics.     

An Efficient, “Burn in” Free Organic Solar Cell Employing a Nonfullerene Electron Acceptor

A comparison of the efficiency, stability, and photophysics of organic solar cells employing poly[(5,6‐difluoro‐2,1,3‐benzothiadiazol‐4,7‐diyl)‐alt‐(3,3′″‐di(2‐octyldodecyl)‐2,2′;5′,2″;5″,2′″‐quaterthiophen‐5,5′″‐diyl)] (PffBT4T‐2OD) as a donor polymer blended with either the nonfullerene acceptor EH‐IDTBR or the fullerene derivative, [6,6]‐phenyl C₇₁ butyric acid methyl ester (PC₇₁BM) as electron acceptors is reported. Inverted PffBT4T‐2OD:EH‐IDTBR blend solar cell fabricated without any processing additive achieves power conversion efficiencies (PCEs) of 9.5 ± 0.2%. The devices exhibit a high open circuit voltage of 1.08 ± 0.01 V, attributed to the high lowest unoccupied molecular orbital (LUMO) level of EH‐IDTBR. Photoluminescence quenching and transient absorption data are employed to elucidate the ultrafast kinetics and efficiencies of charge separation in both blends, with PffBT4T‐2OD exciton diffusion kinetics within polymer domains, and geminate recombination losses following exciton separation being identified as key factors determining the efficiency of photocurrent generation. Remarkably, while encapsulated PffBT4T‐2OD:PC₇₁BM solar cells show significant efficiency loss under simulated solar irradiation (“burn in” degradation) due to the trap‐assisted recombination through increased photoinduced trap states, PffBT4T‐2OD:EH‐IDTBR solar cell shows negligible burn in efficiency loss. Furthermore, PffBT4T‐2OD:EH‐IDTBR solar cells are found to be substantially more stable under 85 °C thermal stress than PffBT4T‐2OD:PC₇₁BM devices.     

Guides “bimorphes” d''ondes ultrasoniques “bimorph” ultrasonic wave guides”

An analysis of the dispersion of elastic waves is presented for two types of long ultrasonics wave-guides that we qualify of “bimorph”: (i) a “three-layer” guide made of two different materials and (ii) a “clad core” guide built up of a rectangular core surrounded by a cladding, the materials of the rod and cladding having different properties. An analytical model is proposed to describe the extensional, flexural and torsional motions in “bimorph” wave guides having two geometrical and material symmetry axes. The asymptotic behaviour of the model allows one to select the material properties which lead to modes guided essentially either in the central layer or in the core of the bimorph guide. Moreover, the dispersive properties of a “bimorph” can be controlled through the choice of geometrical and material parameters.     

“Quasi‐freestanding” Graphene‐on‐Single Walled Carbon Nanotube Electrode for Applications in Organic Light‐emitting Diode

An air‐stable transparent conductive film with “quasi‐freestanding” graphene supported on horizontal single walled carbon nanotubes (SWCNTs) arrays is fabricated. The sheet resistance of graphene films stacked via layer‐by‐layer transfer (LBL) on quartz, and modified by 1‐Pyrenebutyric acid N‐hydroxysuccinimide ester (PBASE), is reduced from 273 Ω/sq to about 76 Ω/sq. The electrical properties are stable to heat treatment (up to 200 ºC) and ambient exposure. Organic light‐emitting diodes (OLEDs) constructed of this carbon anode (T ≈ 89.13% at 550 nm) exhibit ≈88% power efficiency of OLEDs fabricated on an ITO anode (low turn on voltage ≈3.1 eV, high luminance up to ≈29 490 cd/m², current efficiency ≈14.7 cd/A). Most importantly, the entire graphene‐on‐SWCNT hybrid electrodes can be transferred onto plastic (PET) forming a highly‐flexible OLED device, which continues to function without degradation in performance at bending angles >60°.     

“Low-Tech” Innovations

This paper is about an industrial sector which, according to the usual socio-scientific indicators, is referred to as “low-tech”, respectively as non-research intensive and which mostly comprises “traditional” industries. The interest in this sector is motivated by the contradictory situation that, on the one hand, the debate about the perspectives of modern societies focuses on the rapidly growing importance of technological innovations, knowledge and research-intensive economic sectors while, on the other hand, traditional industries make up a considerable fraction of employment and production, especially also in developed economies. On the basis of the results of extensive empirical research, this contribution tries to find answers to the basic question, whether one can speak of an innovation mode typical of the low-tech sector. The institutional based innovation systems approach forms the categorical basis of the analysis. In order to elucidate the specific features of low-tech innovations, they are, in conclusion, compared to the general characteristics of high-tech-based innovation processes.     

Differentiation between the terms ”confined masonry“ and ”infill masonry“

This publication concerns the differentiation between the terms ”confined masonry“ and ”infill masonry“ using the example of the national technical approval Z‐17.1‐1145 – POROTON S9 MW –vertically perforated clay units with integrated thermal insulation using thin layer mortar [1].     

Sniffing the Unique “Odor Print” of Non‐Small‐Cell Lung Cancer with Gold Nanoparticles

A highly sensitive and fast‐response array of sensors based on gold nanoparticles, in combination with pattern recognition methods, can distinguish between the odor prints of non‐small‐cell lung cancer and negative controls with 100% accuracy, with no need for preconcentration techniques. Additionally, preliminary results indicate that the same array of sensors might serve as a better tool for understanding the biochemical source of volatile organic compounds that might occur in cancer cells and appear in the exhaled breath, as compared to traditional spectrometry techniques. The reported results provide a launching pad to initiate a bedside tool that might be able to screen for early stages of lung cancer and allow higher cure rates. In addition, such a tool might be used for the immediate diagnosis of fresh (frozen) tissues of lung cancer in operating rooms, where a dichotomic diagnosis is crucial to guide surgeons.