Carbon Paint Research Articles

Photovoltaic performance improvement in planar P3HT/CdS solar cells induced by structural, optical and electrical property modification in thermal annealed P3HT thin films

Bilayer hybrid solar cells were prepared by solution deposition of CdS thin films on conductive glass substrates (ITO), followed by spin-coating or drop-casting poly (3-hexylthiophene) (P3HT) solution on a CdS surface. After a slow drying process, the P3HT films of different thicknesses (from 100 to 725 nm) were annealed at temperatures (T1) from 110 to 190 °C, called pre-metal contact annealing. Then carbon paint was collocated on top of P3HT and gold was evaporated. The whole structure was annealed for the second time, called post-metal contact annealing, at temperature (T2) between 110 and 190 °C. The continuous increase of the (1 0 0) crystalline plane and the optical absorption coefficient of P3HT films with annealing temperatures indicates the improvement of molecular order inside the polymer films induced by the thermal annealing process. The better ordered P3HT films lead to lower series resistance and higher fill factor in the corresponding solar cells, suggesting the enlargement of charge carrier mobility in annealed P3HT films. On the other hand, the photovoltaic performance is also affected by T2 temperature; a low T2 improves the ohmic contact between P3HT and the metal contact to benefit the charge carrier extraction, whereas a high T2 may deteriorate that union. The same observation was obtained in CdS/P3HT solar cells with P3HT films of different thicknesses. The best energy conversion efficiency of 0.44% was obtained in CdS/P3HT cells with 305 nm thick P3HT annealed at T1 = 190 °C and T2 = 110 °C for 10 min each.

Very High Laser-Damage Threshold of Polymer-derived Si(B)CN- Carbon Nanotube Composite Coatings

We study the laser irradiance behavior and resulting structural evolution of polymer-derived silicon-boron-carbonitride (Si(B)CN) functionalized multiwall carbon nanotube (MWCNT) composite spray coatings on copper substrate. We report a damage threshold value of 15 kWcm(-2) and an optical absorbance of 0.97 after irradiation. This is an order of magnitude improvement over MWCNT (1.4 kWcm(-2), 0.76), SWCNT (0.8 kWcm(-2), 0.65) and carbon paint (0.1 kWcm(-2), 0.87) coatings previously tested at 10.6 μm (2.5 kW CO2 laser) exposure. Electron microscopy, Raman spectroscopy, and X-ray photoelectron spectroscopy suggests partial oxidation of Si(B)CN forming a stable protective SiO2 phase upon irradiation.

Distinguishing between Mineral Paint and Carbon Paint on Ancestral Puebloan Pottery

Archaeologists have found that the elements present in the pigments used on Ancestral Puebloan black-on-white painted pottery are an important descriptive attribute. They typically describe the pigments used to produce these painted designs as either carbon-based (containing primarily organic compounds) or mineral-based (containing primarily iron compounds), although in some cases these pigments are combined or “mixed”.

SU‐FF‐T‐373: Investigation of Humidity Effects On Beam Monitor Performance in a Proton Clinical Gantry

Purpose: To investigate the effect of ambient humidity on performance characteristics of ionization chambers used as beam monitors in two clinical proton gantry systems, and to choose optimal electrode materials. Method and Materials: Dose calibration results for two identical, vented beam monitors, with electrodes constructed of Mylar film with graphite coating, and each installed in a gantry nozzle, were analyzed for stability over a period of 1 year. Additionally, two ion chambers of similar design, but constructed using Kapton for base layer and either i) gold‐plated copper or ii) graphite paint for electrodes, were fabricated for testing purposes. The test chambers were placed in a controlled humidity environment and their performance was evaluated in a proton beam under various humidity conditions. Results: Mylar‐based electrodes of the gantry beam monitors provide a dose calibration that varied within ±2% (maximum deviation from mean), over a period of 1 year while room's relative humidity (RH) varied from 20% to 70%, with brief excursions to 15% and 80%. Kapton‐based copper gold‐plated electrodes provided linear (±1%) response in dose rates up to 180 Gy/min, and were stable within ±1% in terms of measured charge per monitor unit, in the range of 10%–90% RH. The response of Kapton‐based carbon paint electrodes was linear (±1%) in dose rate up to 8 Gy/min and showed a slight rising trend (about 3% increase) in the 50% – 80% RH range. Conclusion: Treatment room humidity may affect the performance of Mylar‐based electrodes in a beam monitor with open‐to‐atmosphere design. When humidity of 70% RH or higher is possible, copper gold‐plated electrodes on Kapton show superior performance compared with graphite paint electrodes.

Effect of photoelectric emission on blunt probe conductivity measurements in the stratosphere

Two identical planar blunt probes of stainless steel material, biased with a bipolar ramp voltage, are used to measure the stratospheric polar conductivities to altitudes of 34 km. One probe (DP) is mounted closer to the gondola, looking downwards and shielded from sunlight, while the other (SP) is mounted looking sideways, away from the gondola. The daytime observations of positive ions in the 29–34 km altitude range with SP, and of negative ions at 34 km with DP, show photoelectric contaminations induced by solar UV radiations in the 190–230 nm band. These contaminations are found to be due to photoemissions from the SP probe steel surface and from the carbon paint that coats the surface of the gondola, respectively. It is found that, a segment of the photocurrent contaminated I– V curve, recorded with SP at higher negative probe potentials, is linear, and it can give the ambient positive polar conductivity.

Exposure Programme on Atmospheric Corrosion Effects of Acidifying Pollutants in Tropical and Subtropical Climates

Many national exposure programmes have been performed in tropical and subtropical climates during the last 50 years. However, ambitious programmes involving more than a few countries are scarce. In this paper a recently formed network of test sites is described involving 12 test sites in Asia (India, Vietnam, Thailand, Malaysia and China including Hong Kong) and four test sites in Africa (South Africa, Zambia and Zimbabwe). This effort is part of the 2001–2004 Swedish International Development Agency (SIDA) funded Programme on Regional Air Pollution in Developing Countries (RAPIDC). Corrosion attack after one (2002–2003) year of exposure (carbon steel, zinc, copper, limestone and paint coated steel) are presented together with environmental data (SO2, NO2, HNO3, O3, particles, amount and pH of precipitation, temperature and relative humidity) for all the test sites. The obtained corrosion values are substantially higher than expected for limestone, higher than expected for carbon steel and lower than expected for zinc compared to values calculated using the best available dose–response functions.

New electrical potential method for measuring crack growth in nonconductive materials

DC electric potential technique has been used to monitor crack growth in conductive materials. A constant DC current is passed through these materials and the crack length is measured through the changes in the electrical voltage at the crack mouth. However, this method is not applicable in crack growth measurement in nonconductive materials or adhesively bonded joints. For these materials, a new method is developed and is shown to provide a very accurate method for measuring the crack length. The surface of these materials is coated with a thin layer of carbon paint and the crack length is measured through the changes in the electrical resistance of the carbon paint, as the crack grows both in the base material and the thin layer carbon paint. In contrast to the DC electric potential technique where the position of the probes for measuring the crack length is very important for an accurate measurement of the crack length, the new technique is little sensitive to the probe location. Crack growth is measured in adhesively bonded joints subjected to creep loadings. A modified compact tension specimen is cut in two pieces across its notch area. The pieces are then glued using an adhesive. The surface of the specimen is painted with a thin layer of carbon paint and the changes in its electrical resistance are monitored. It is shown that the carbon paint method provides a quiet sensitive method for monitoring the crack growth. The creep crack growth rate in the adhesively bonded joint is related to Mode I energy release rate, G 1. It is shown that the crack grows in the middle of the adhesive layer rather than at the interface of the joint. Micro-mechanisms of the crack growth are studied using a scanning electron microscope. The damage consists of numerous crazed regions at the crack tip. Crack grows by the linkage of the crazed region.

The “Wired” Laccase Cathode: High Current Density Electroreduction of O2 to Water at +0.7 V (NHE) at pH 5

The “Wired” Laccase Cathode: High Current Density Electroreduction of O₂ to Water at +0.7 V (NHE) at pH 5

Maxwellian Charge on Ferroelectric Domain Walls in KNBO3

Abstract Ferroelectrics are now being used as non-volatile memories, infrared detectors, phased array radar and optical switches. Although the development of commercial ferroelectric devices has advanced in recent years, we still do not have a clear understanding of the basic physics underpinning the behavior of actual ferroelectric devices. Trapped charge and oxygen vacancies are believed to strongly influence domain motion. In order to study these issues, we have designed an in situ TEM holder that can subject ferroelectric crystals to voltage, heat and UV irradiation. Preliminary results on BaTiO3 have been presented in previous reports. In this study, bulk KNbO3 crystals were mechanically polished and thinned in hot orthophosphoric acid. The resulting thin flakes were attached to copper rings with conductive carbon paint, and electrical wires were glued to the copper rings which act as electrodes. The sample was placed in the cradle of the in situ TEM holder and examined in a Hitachi H9000NAR TEM.

In Situ Observation of Ferroelectric Domain Motion in BaTiO3

Abstract Ferroelectrics are used in many applications such as non-volatile memory, infrared detectors, phased array radar and optical switches. While substantial progress has been made in the development of commercial ferroelectric devices, we still do not possess a good understanding of the fundamental processes in ferroelectrics. Trapped charge and oxygen vacancies are believed to strongly influence domain motion. In order to study these issues, we have designed an in situ TEM holder that can subject ferroelectric crystals to voltage, heat and UV irradiation. Bulk BaTi03 crystals, grown by the Remeika method, were mechanically polished and thinned in hot ophosphoric acid. The resulting thin flakes were attached to copper rings with conductive carbon paint and electrical wires were glued to the copper rings, which act as electrodes. The sample was placed in the cradle of the in situ TEM holder and examined in a Hitachi H9000NAR TEM.

Photovoltaic Properties of Sintered CdS / CdTe Solar Cells Doped with Cu

All polycrystalline solar cells doped with Cu have been prepared by a screen printing and sintering method. Cell parameters of the sintered solar cells have been investigated in an attempt to find out the optimum doping conditions and concentrations of Cu by adding various amounts of either into layer or into back contact carbon layer. Cell parameters of the sintered solar cells which contained various amounts of in the layers before sintering stay at about the same values as the amount of increases up to 25 ppm, and then decreases sharply as the amount of further increases. The Cu added in the layer diffuses into the layer during the sintering of the composite at 625°C to densify the layer and causes the decrease in the optical transmission of resulting in the degradation of the cell performance. In case the Cu dopant was dispersed in the back carbon paint and was followed by annealing, all cell parameters are improved significantly compared with those fabricated by adding in the layer before sintering. A sintered solar cell which contained 25 ppm in the carbon paste and was annealed at 350°C for 10 min shows the highest efficiency. The efficiency of this cell is 12.4% under solar irradiation with an intensity of 80.4 mW/cm2.

ChemInform Abstract: Effects of Annealing Conditions of Electrodes on the Photovoltaic Properties of Sintered Cadmium Sulfide/Cadmium Telluride Solar Cells.

AbstractPolycrystalline n‐CdS/p‐CdTe solar cells are fabricated using a commercial carbon paint as ohmic contact for the CdTe layer and a silver paint mixed with 20% In powder as contact for CdS.

Effects of Annealing Conditions of Electrodes on the Photovoltaic Properties of Sintered Cadmium Sulfide/Cadmium Telluride Solar Cells

Polycrystalline n‐CdS/p‐CdTe solar cells with a commerical carbon paint on the p‐CdTe layer and an In‐Ag paint on the n‐CdS layer were fabricated by a coating and sintering method. Electrical properties of the conducting paints and solar cell parameters of the heterojunction solar cells were investigated as a function of electrode annealing conditions. The sintered CdS/CdTe solar cells whose electrode contacts were annealed at 350°C for 10 min in nitrogen showed maximum values of short‐circuit current density, fill factor, and solar efficiency. Commercial carbon and silver paints can be used as electrodes to fabricate sintered CdS/CdTe solar cells with efficiency over 10%.

Transmitted Infrared Photography

In a recent article in Studies in Conservation [1] Mr Alec Cobbe, discussing colormen 5 canvas stamps, says that there is no way of observing these if they are covered by relining. There is a way of observing them and other inscriptions providing that the marking is done in dark or carbon ink or paint, and is behind white lead or certain other light colors which are on the front of the painting. Informally, after a conference at Boston in 1965, William J. Young in a conversation discussed the subject of transmitted infrared (IR). The whole thing seemed so impossible that I set out to prove it would reveal nothing. However I was very wrong. A relined English portrait with characteristic heavy white lead paint on the forehead (3 mm thick) was set up with its reverse to direct sunlight. Facing this I set up my camera loaded with IR sensitive film (the slow Eastman-Kodak IR film available at that time) and with the lens covered by a dark red filter. Several exposures were tried but I have no record of the exact successful one which revealed, in the area of heaviest white lead, the stamp of 'ROBERSON' and 'MILLER', this becoming less legible towards the area of darker modelling. Later, by letter, Bill Young confirmed my findings. White lead is relatively transparent to IR but opaque to X-rays while carbon black absorbs IR but is transparent to X-rays. Among other points which he made were that better results might be obtained using IR drying lamps in place of sunlight with an 88 filter on the camera, and the advisability of shielding all visible light from the camera side of the painting. When the lining was later removed the stamp was found to read 'Prepared by Roberson and Miller, 51 Long Acre, London'. Below this was a hand mark