Peter James Maroulis

Life-Cycle Nitrogen Trifluoride Emissions from Photovoltaics

Amorphous- and nanocrystalline-silicon thin-film photovoltaic modules are made in high-throughput manufacturing lines that necessitate quickly cleaning the reactor. Using NF₃, a potent greenhouse gas, as the cleaning agent triggered concerns as recent reports reveal that the atmospheric concentrations of this gas have increased significantly. We quantified the life-cycle emissions of NF₃ in photovoltaic (PV) manufacturing, on the basis of actual measurements at the facilities of a major producer of NF₃ and of a manufacturer of PV end-use equipment. From these, we defined the best practices and technologies that are the most likely to keep worldwide atmospheric concentrations of NF₃ at very low radiative forcing levels. For the average U.S. insolation and electricity-grid conditions, the greenhouse gas (GHG) emissions from manufacturing and using NF₃ in current PV a-Si and tandem a-Si/nc-Si facilities add 2 and 7 g CO₂(eq)/kWh, which can be displaced within the first 1-4 months of the PV system life.

Determination of toluene diisocyanates in polyurethane prepolymers using capillary supercritical fluid chromatography

Abstract A method has been developed for the quantitative determination of toluene diisocyanates (TDI) in polyurethane prepolymers using capillary supercritical fluid chromatography. Quantitation was achieved by using an internal standard. The precision of the method was determined to be ±3%. Chromatographic conditions producing various degrees of TDI isomer resolution are reported. Results from the determination of TDI in six prepolymers are compared to results obtained using high-performance liquid chromatography for the same six prepolymers.

Reduction of PFC emissions to the environment through advances in CVD and etch processes

One the most focused environmental health and safety (EHS) goals for the semiconductor industry has been to reduce perfluorocompound (PFC) emissions because of their high global warming potentials and long residence times in the atmosphere. During the last decade, significant achievements have been reached in attaining this goal. Chemical vapor deposition (CVD) chamber cleaning and plasma etch are two processes that use PFCs in which studies have been conducted to reduce emissions. Two successful strategies for reducing PFC emissions and enhancing process performance are described.