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O2 Plasma (o2 + plasma)
Selected AbstractsAnode Interfacial Tuning via Electron-Blocking/Hole-Transport Layers and Indium Tin Oxide Surface Treatment in Bulk-Heterojunction Organic Photovoltaic CellsADVANCED FUNCTIONAL MATERIALS, Issue 4 2010Alexander W. Hains Abstract The effects of anode/active layer interface modification in bulk-heterojunction organic photovoltaic (OPV) cells is investigated using poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) and/or a hole-transporting/electron-blocking blend of 4,4,-bis[(p -trichlorosilylpropylphenyl)-phenylamino]biphenyl (TPDSi2) and poly[9,9-dioctylfluorene- co - N -[4-(3-methylpropyl)]-diphenylamine] (TFB) as interfacial layers (IFLs). Current,voltage data in the dark and AM1.5G light show that the TPDSi2:TFB IFL yields MDMO-PPV:PCBM OPVs with substantially increased open-circuit voltage (Voc), power conversion efficiency, and thermal stability versus devices having no IFL or PEDOT:PSS. Using PEDOT:PSS and TPDSi2:TFB together in the same cell greatly reduces dark current and produces the highest Voc (0.91,V) by combining the electron-blocking effects of both layers. ITO anode pre-treatment was investigated by X-ray photoelectron spectroscopy to understand why oxygen plasma, UV ozone, and solvent cleaning markedly affect cell response in combination with each IFL. O2 plasma and UV ozone treatment most effectively clean the ITO surface and are found most effective in preparing the surface for PEDOT:PSS deposition; UV ozone produces optimum solar cells with the TPDSi2:TFB IFL. Solvent cleaning leaves significant residual carbon contamination on the ITO and is best followed by O2 plasma or UV ozone treatment. [source] Surface Modification of Poly(propylene) Microporous Membrane to Improve Its Antifouling Characteristics in an SMBR: O2 Plasma TreatmentPLASMA PROCESSES AND POLYMERS, Issue 1 2008Hai-Yin Yu Abstract Fouling is the major obstacle in membrane processes applied in water and wastewater treatment. To improve the antifouling characteristics of PPHFMMs in an SMBR for wastewater treatment, the PPHFMMs were surface-modified by O2 low temperature plasma treatment. Structural and morphological changes on the membrane surface were characterized by XPS and FE-SEM. The change of surface wettability was monitored by contact angle measurements. Results of XPS clearly indicated that the plasma treatment introduced oxygen containing polar groups on the membrane surface. The static water contact angle of the modified membrane reduced obviously with the increase of plasma treatment time. The relative pure water flux for the modified membranes increased with plasma treatment time up to 1 min, then it decreased with further increase of plasma treatment time. Decreases in the tensile strength and the tensile elongation at break of the modified membranes were also observed. To assess the relation between the plasma treatment and the membrane fouling in an SMBR, filtration for activated sludge was carried out by using synthetic wastewater. After continuous operation in the SMBR for about 75 h, flux recovery were 8.7 and 12.3%, reduction of flux were 91.6 and 87.4% for the nascent and O2 plasma treated PPHFMM for 1 min, relative flux ratio for O2 plasma treated PPHFMM for 1 min was 49.9% higher than that of the nascent PPHFMM. [source] Impact of Low-Temperature Plasmas on Deinococcusradiodurans and BiomoleculesBIOTECHNOLOGY PROGRESS, Issue 3 2003Rakesh Mogul The effects of cold plasma on Deinococcus radiodurans, plasmid DNA, and model proteins were assessed using microbiological, spectrometric, and biochemical techniques. In low power O2 plasma (,25 W, ,45 mTorr, 90 min), D. radiodurans, a radiation-resistant bacterium, showed a 99.999% reduction in bioburden. In higher power O2 plasma (100 W and 500 mTorr), the reduction rate increased about 10-fold and observation by atomic force microscopy showed significant damage to the cell. Damage to cellular lipids, proteins, and chromosome was indicated by losses of infrared spectroscopic peaks at 2930, 1651, 1538, and 1245 cm - 1, respectively. In vitro experiments show that O2 plasmas induce DNA strand scissions and cross-linking as well as reduction of enzyme activity. The observed degradation and removal of biomolecules was power-dependent. Exposures to 200 W at 500 mTorr removed biomolecules to below detection limits in 60 s. Emission spectroscopy indicated that D. radiodurans cells were volatilized into CO2, CO, N2, and H2O, confirming that these plasmas were removing complex biological matter from surfaces. A CO2 plasma was not as effective as the O2 plasma, indicating the importance of plasma composition and the dominant role of chemical degradation. Together, these findings have implications for NASA planetary protection schemes and for the contamination of Mars. [source] Plasmas for texturing, cleaning, and deposition: towards a one pump down process for heterojunction solar cellsPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 3-4 2010Mario Moreno Abstract Low temperature plasma deposition of a-Si:H thin films has emerged as a promising alternative for high efficiency hetero junction (HJ) solar cells. In this work we study plasma processes for texturing and cleaning c-Si wafers pursuing a low cost dry fabrication process of HJ solar cells. We have studied two independent plasma processes: i) Texturing of c-Si wafers using SF6 - O2 plasmas in a RIE system, in order to reduce the surface reflectance and therefore improve the light trapping. The effects of the RF power and gas ratio on the c-Si surface texture have been studied in detail. Highly textured surfaces, with very low reflectance values (around 6% in the range of 300 , 1000 nm) have been achieved. ii) Etching of the native oxide and passivation of the c-Si surface by plasma, in a standard RF PECVD system. We used SiF4 plasma with optimized conditions for an efficient native oxide removal, and without breaking the vacuum, 40 nm of a-Si:H were deposited in order to passivate the c-Si surface. High effective lifetime values were obtained (,eff , 1.5 ms), providing high implicit open circuit voltages (Voc , 0.713 V) and low surface recombination velocities (Seff < 9 cm s -1). (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Impact of Low-Temperature Plasmas on Deinococcusradiodurans and BiomoleculesBIOTECHNOLOGY PROGRESS, Issue 3 2003Rakesh Mogul The effects of cold plasma on Deinococcus radiodurans, plasmid DNA, and model proteins were assessed using microbiological, spectrometric, and biochemical techniques. In low power O2 plasma (,25 W, ,45 mTorr, 90 min), D. radiodurans, a radiation-resistant bacterium, showed a 99.999% reduction in bioburden. In higher power O2 plasma (100 W and 500 mTorr), the reduction rate increased about 10-fold and observation by atomic force microscopy showed significant damage to the cell. Damage to cellular lipids, proteins, and chromosome was indicated by losses of infrared spectroscopic peaks at 2930, 1651, 1538, and 1245 cm - 1, respectively. In vitro experiments show that O2 plasmas induce DNA strand scissions and cross-linking as well as reduction of enzyme activity. The observed degradation and removal of biomolecules was power-dependent. Exposures to 200 W at 500 mTorr removed biomolecules to below detection limits in 60 s. Emission spectroscopy indicated that D. radiodurans cells were volatilized into CO2, CO, N2, and H2O, confirming that these plasmas were removing complex biological matter from surfaces. A CO2 plasma was not as effective as the O2 plasma, indicating the importance of plasma composition and the dominant role of chemical degradation. Together, these findings have implications for NASA planetary protection schemes and for the contamination of Mars. [source] | ||||||||||