Energetically Autonomous, Wearable, and Multifunctional Sensor

Self-powered tactile sensing is the upcoming technological orientation for developing compact, robust, and energy-saving devices in human-machine interfacing and electronic skin. Here, we report an intriguing type of sensing device composed of a Pt crack-based sensor in series with a polymer solar cell as a building block for energetically autonomous, wearable, and tactile sensor. This coplanar device enables human activity and physiological monitoring under indoor light illumination (2 mW/cm²) with acceptable and readible output signals. Additionally, the device can also function as a photodetector and a thermometer owing to the rapid response of the solar cell made from polymers. Consequently, the proposed device is multifuntional, mechanically robust, flexible, stretchable, and eco-friendly, which makes it suitable for long-term medical healthcare and wearable technology as well as environmental indication. Our designed green energy powered device therefore opens up a new route of developing renewable energy based portable and wearable systems

Ultrafast and Ultrasensitive Gas Sensors Derived from a Large Fermi-Level Shift in the Schottky Junction with Sieve-Layer Modulation

Gas sensors play an important role in numerous fields, covering a wide range of applications, including intelligent systems and detection of harmful and toxic gases. Even though they have attracted much attention, the response time on the order of seconds to minutes is still very slow. To circumvent the existing problems, here, we provide a seminal attempt with the integration of graphene, semiconductor, and an addition sieve layer forming a nanocomposite gas sensor with ultrahigh sensitivity and ultrafast response. The designed sieve layer has a suitable band structure that can serve as a blocking layer to prevent transfer of the charges induced by adsorbed gas molecules into the underlying semiconductor layer. We found that the sensitivity can be reduced to the parts per million level, and the ultrafast response of around 60 ms is unprecedented compared with published graphene-based gas sensors. The achieved high performance can be interpreted well by the large change of the Fermi level of graphene due to its inherent nature of the low density of states and blocking of the sieve layer to prevent charge transfer from graphene to the underlying semiconductor layer. Accordingly, our work is very useful and timely for the development of gas sensors with high performance for practical applications

Electrically Driven White Light Emission from Intrinsic Metal–Organic Framework

Light-emitting diodes (LEDs) have drawn tremendous potential as a replacement of traditional lighting due to its low-power consumption and longer lifetime. Nowadays, the practical white LEDs (WLED) are contingent on the photon down-conversion of phosphors containing rare-earth elements, which limits its utility, energy, and cost efficiency. In order to resolve the energy crisis and to address the environmental concerns, designing a direct WLED is highly desirable and remains a challenging issue. To circumvent the existing difficulties, in this report, we have designed and demonstrated a direct WLED consisting of a strontium-based metal–organic framework (MOF), {[Sr­(ntca)­(H₂O)₂]·H₂O}_<i>n</i> (<b>1</b>), graphene, and inorganic semiconductors, which can generate a bright white light emission. In addition to the suitable design of a MOF structure, the demonstration of electrically driven white light emission based on a MOF is made possible by the combination of several factors including the unique properties of graphene and the appropriate band alignment between the MOF and semiconductor layer. Because electroluminescence using a MOF as an active material is very rare and intriguing and a direct WLED is also not commonly seen, our work here therefore represents a major discovery which should be very useful and timely for the development of solid-state lighting

”Får jag också fråga en varför-fråga?” En studie om elevers upplevelse av ett skolprojekt

Syftet med detta arbete är att få syn på och försöka förstå elevers perspektiv gällande ett skolprojekt som de varit delaktiga i under höstterminen 2011. Skolprojektets tema var ”Människan och samhället” och dess syfte var att ge eleverna möjlighet att uttrycka sig med hjälp av och prova på olika estetiska gestaltningsformer. Skolprojektet avslutades i en hybridutställning. Vår emperi består av material insamlat under skolprojektets gång, så som filmade klassrumssituationer, elevers loggboksanteckningar och elevutvärderingar. Dessutom genomförde vi efteråt fem kvalitativa semi-strukturerade intervjuer med elevinformanter som deltagit i skolprojektet. Det empiriska materialet kommer vi sätta i relation till begrepp som estetik, kreativitet och deltagar- och åskådarkultur. I vårt arbete kan vi se att de flesta eleverna upplever det som något lustfullt och roligt att jobba med estetiska uttrycksformer – så länge det inte betyder att de behöver reflektera eller diskutera sina produktioner. Detta ser vi som en direkt konsekvens av den skolkontext de är vana vid, där ett prövande och ifrågassättande arbetssätt inte präglar elevernas uppfattning om vad skolan kräver av dem. I vårt arbete analyserar vi också denna uppfattning och hur den kan tyckas vara ett resultat av ”de rätta svarens pedagogik”. Det vi kommer fram till är att det är komplext att kartlägga elevers upplevelser; begreppen räcker kanske inte till för att få syn på elevers perspektiv

Application of Supramolecular Assembly of Porphyrin Dimers for Bulk Heterojunction Solar Cells

Recently, there has been a growing interest in developing porphyrin derivatives as electron donor materials in solution-processed organic solar cells. In contrast to the traditional synthesis route, we adopt a ligand-mediated supramolecular assembly approach to produce a new soluble porphyrin derivative. The complexation of nitrogen lone pairs in the bidentate ligands to the axial orbitals of both zinc atoms in zinc-metalated porphyrin dimers (KC2s) form KC2-duplex. The UV–vis absorbance of KC2-duplex displays a red-shift of the Q-band compared with that of KC2, indicating an improvement of intermolecular interaction. By blending KC2-duplex with [6,6]-phenyl-C₇₁-butyric acid methyl ester (PC₇₁BM) as the photoactive material for fabricating organic bulk heterojunction solar cells, the devices demonstrate a 38.7% enhancement of short-circuit current density (<i>J</i>_sc) as compared to those made from dimers. The largely enhanced <i>J</i>_sc is attributed to the improved charge transport dynamics of KC2-duplex:PC₇₁BM blend, including the hole and effective mobilities and exciton dissociation probability. When the photoactive film is processed from solvent containing 3% v/v 1-chloronaphthalene, <i>J</i>_sc is further enhanced (∼64.5%) as well as the fill factor (16.7%) for a power conversion efficiency of 3.06% from 1.63%. Our approach shown here can be generalized to other porphyrin-related systems to advance the development of porphyrin-based optoelectronic devices

Electrically Driven White Light Emission from Intrinsic Metal–Organic Framework

Light-emitting diodes (LEDs) have drawn tremendous potential as a replacement of traditional lighting due to its low-power consumption and longer lifetime. Nowadays, the practical white LEDs (WLED) are contingent on the photon down-conversion of phosphors containing rare-earth elements, which limits its utility, energy, and cost efficiency. In order to resolve the energy crisis and to address the environmental concerns, designing a direct WLED is highly desirable and remains a challenging issue. To circumvent the existing difficulties, in this report, we have designed and demonstrated a direct WLED consisting of a strontium-based metal–organic framework (MOF), {[Sr­(ntca)­(H₂O)₂]·H₂O}_<i>n</i> (<b>1</b>), graphene, and inorganic semiconductors, which can generate a bright white light emission. In addition to the suitable design of a MOF structure, the demonstration of electrically driven white light emission based on a MOF is made possible by the combination of several factors including the unique properties of graphene and the appropriate band alignment between the MOF and semiconductor layer. Because electroluminescence using a MOF as an active material is very rare and intriguing and a direct WLED is also not commonly seen, our work here therefore represents a major discovery which should be very useful and timely for the development of solid-state lighting

Media 3: Optically tunable and detectable magnetoelectric effects in the composite consisting of magnetic thin films and InGaN/GaN multiple quantum wells

Originally published in Optics Express on 26 August 2013 (oe-21-17-19934

Media 1: Optically tunable and detectable magnetoelectric effects in the composite consisting of magnetic thin films and InGaN/GaN multiple quantum wells

Originally published in Optics Express on 26 August 2013 (oe-21-17-19934

Media 6: Optically tunable and detectable magnetoelectric effects in the composite consisting of magnetic thin films and InGaN/GaN multiple quantum wells

Originally published in Optics Express on 26 August 2013 (oe-21-17-19934

Media 2: Optically tunable and detectable magnetoelectric effects in the composite consisting of magnetic thin films and InGaN/GaN multiple quantum wells

Originally published in Optics Express on 26 August 2013 (oe-21-17-19934