Improved room-temperature thermoelectric characteristics in F4TCNQ-doped CNT yarn/P3HT composite by controlled doping

High room-temperature thermoelectric performance is important for low-grade waste heat power generation as there are plenty of heat thrown away uselessly in our daily life, most of which are below 100 °C. However, most of the thermoelectric materials are limited to high temperature application. In this work, room-temperature thermoelectric power factor of carbon nanotube (CNT) yarn is improved by controlled doping, which is achieved by making composite with poly 3-hexylthiophene −2, 5-diyl (P3HT) followed by doping with 2, 3, 5, 6-tetrafluo-7, 7, 8, 8-tetracyanoquinodimethane (F4TCNQ). The temperature-dependent Seebeck coefficient based on power–law model suggests that P3HT shifts the Fermi energy of CNT yarn towards the valence band edge, and reduces the ionic scattering and carrier relaxation time. As a result, the Seebeck coefficient is increased while the variation of Seebeck coefficient with temperature is reduced, and hence, the room-temperature thermoelectric power factor is improved. With controlled doping, the power factor of CNT yarn/P3HT composite reaches to 1640–2160 μW m⁻¹K⁻² at the temperature range of 25–100 °C, which is higher than that of CNT yarn alone.     

The role of solvent and morphology on miscibility of methanofullerene and poly(3-hexylthiophene)

A bicontinuous, percolating bulk heterojunction morphology is integral to organic polymer solar cells. Understanding the factors affecting the miscibility of photovoltaic polymers with a fullerene electron acceptor molecule is a key to controlling the morphology. Starting from discreet pure phases - a poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl-C₆₁-butyric acid methyl ester (PCBM) bilayer film - the evolution of the P3HT-PCBM interface was studied with particular attention to the role of residual solvent in P3HT on PCBM interdiffusion. This investigation shows that in the bilayer geometry PCBM can rapidly diffuse into amorphous P3HT, but phase separation is maintained if the P3HT layer is cast from a very volatile solvent or if it is annealed prior to casting the PCBM overlayer to complete the bilayer geometry.     

Temperature treatment of semiconducting polymers: An X-ray reflectivity study

The influence of temperature treatment on three types of conjugated polymer thin films, named poly(3-hexylthiophene) (P3HT), polyarylamine (PAA) and octylfluorene-bithiophene copolymer (F8T2) is studied. A detailed knowledge of the film morphology and crystalline structure is important since the performance of organic thin film transistors is extremely sensitive to small changes of morphology and structure. Samples are prepared via a spin-casting process on thermal oxidized silicon wafers. The influence of heat treatment in the range from ambient temperatures to 600 K is studied with specular X-ray reflectivity, X-ray diffraction and differential scanning calorimetry. The morphological parameters like layer thicknesses, electron densities and roughnesses of the interface and of the surface are calculated from the XRR measurements. The maximum change of layer thickness due to heat treatment is 15% of the initial layer thicknesses. The maximum variation of the mean electron densities are about 20% and the rms surface roughness vary from 2 Å up to 20 Å as a result of annealing. Interface roughness show variation of about 1 Å. Strong variations of the morphological parameters next to phase transition temperatures are observed as well.     

用异步收发器HT6720设计RFID系统

HT6720是可在射频识别系统中制作电子标签的专用集成电路，工作频率为13．56MHz，属于中频识别芯片。该芯片内置96bit OPT存储器，且为只读型。由于HT6720所需要的数据载体结构简单，因此，通过HT6720可用极低的成本生产只读标签和设计射频识别系统。     

Biindene-C60 adducts for the application as acceptor in polymer solar cells with higher open-circuit-voltage

Two C₆₀ derivatives, biindene-C₆₀ monoadduct (BC₆₀MA) and biindene-C₆₀ bisadduct (BC₆₀BA), were synthesized by an one-pot reaction of 1, 1′-biindene and C₆₀, for the application as acceptor materials in Polymer Solar Cells (PSCs). The two C₆₀ derivatives possess good solubility in toluene and o-dichlorobenzene, and the solubility of BC₆₀BA is even better than that of BC₆₀MA. The electrochemical properties and the LUMO energy levels of the two fullerene derivatives were investigated by cyclic voltammetry. The LUMO energy levels of BC₆₀MA and BC₆₀BA were 0.06 and 0.17 eV higher (up-shifted) than that of PCBM, respectively. The PSCs based on P3HT as donor and BC₆₀MA or BC₆₀BA as acceptor exhibited higher V_oc of 0.68 and 0.82 V, respectively, which is benefited from the higher LUMO energy levels of the C₆₀ derivatives. The power conversion efficiency of the PSC based on P3HT/BC₆₀MA was 2.21% after annealing at 140 °C for 5 min.     

Gravure printing for three subsequent solar cell layers of inverted structures on flexible substrates

Inverted organic photovoltaic devices have been fabricated by gravure printing on a flexible substrate. In order to enable printing of multiple layers sequentially, a systematic study of wetting behaviour of each layer in the device is performed. Successful wetting of a hydrophobic P3HT:PCBM surface by a hydrophilic PEDOT:PSS ink is achieved with the addition of a surfactant/alcohol to the PEDOT:PSS ink and with oxygen plasma treatment. We are therefore able to print titanium oxide, poly(3-hexylthiophene) (P3HT) blended with [6,6]-phenyl C61 butyric acid methyl ester (PCBM) and poly-3,4-ethylenedioxythiophene:poly(styrene sulphonic acid) (PEDOT:PSS). As result we get for three printed layers a 0.6% power conversion efficiency.     

An experimental aluminum-fueled power plant

An experimental co-generation power plant (CGPP-10) using aluminum micron powder (with average particle size up to 70 μm) as primary fuel and water as primary oxidant was developed and tested. Power plant can work in autonomous (unconnected from industrial network) nonstop regime producing hydrogen, electrical energy and heat. One of the key components of experimental plant is aluminum-water high-pressure reactor projected for hydrogen production rate of ∼10 nm³ h⁻¹. Hydrogen from the reactor goes through condenser and dehumidifier and with −25 °C dew-point temperature enters into the air-hydrogen fuel cell 16 kW-battery. From 1 kg of aluminum the experimental plant produces 1 kWh of electrical energy and 5-7 kWh of heat. Power consumer gets about 10 kW of electrical power. Plant electrical and total efficiencies are 12% and 72%, respectively.     

Nano-scale mechanical properties of polymer/fullerene bulk hetero-junction films and their influence on photovoltaic cells

Mechanical properties of poly(3-hexylthiophene) (P3HT)/[6,6]-phenyl-C61-butyric acid methyl ester (PCBM) blend films, prepared under different processing conditions, were evaluated by nanoindentation. Photovoltaic devices fabricated using above active layers presented the highest power conversion efficiencies for blend films having lowest Young’s modulus (20.73 GPa) and hardness (649 MPa), as measured by a nanoidentator under optimized conditions of blend proportion (1:1), film drying rate (slow) and annealing temperature and time (110 °C and 10 min). It implies that the degree of nano-scale phase separation for the P3HT:PCBM blend is strongly correlated with the mechanical properties in the nanodimension. The nanoindentation is a method to estimate nano-scale mechanical properties of blend films and the performance of photovoltaic cells.     

Poly‐3‐hexylthiophene doped with iron disulfide nanoparticles for hybrid solar cells

In this work, the pyrite crystalline phase of iron disulfide nanoparticles (FeS₂) about 20 to 30 nm was obtained by a two‐pot thermal method at 220°C. Subsequently, different concentrations of these nanoparticles were used as a doping agent for the conjugated poly‐3‐hexylthiophene (P3HT). The electrical resistivity of P3HT was decreased almost three orders of magnitude while adding FeS₂ nanoparticles as doping, and dichlorobenzene solvent was a determinant factor for the dispersion of polymer with nanoparticles. Doped‐P3HT dichlorobenzene solution was spin coated onto the FTO/TiO₂ substrate to fabricate the FTO/TiO₂/P3HT:FeS₂/C‐Au hybrid solar cells. Moreover, the power conversion efficiency (PCE) of hybrid devices was studied as a function of pyrite FeS₂ nanoparticle concentration. The highest efficiency of 0.83% was obtained at 1% concentration of FeS₂ nanoparticles. Hence, the results revealed that the FeS₂ nanoparticles could be considered as an alternative charge carrier to develop the bulk hybrid solar cells.