Close-Space Sublimation-Deposited Ultra-Thin CdSeTe/CdTe Solar Cells for Enhanced Short-Circuit Current Density and Photoluminescence.

Developments in photovoltaic device architectures are necessary to make solar energy a cost-effective and reliable source of renewable energy amidst growing global energy demands and climate change. Thin film CdTe technology has demonstrated cost-competitiveness and increasing efficiencies due partially to rapid fabrication times, minimal material usage, and introduction of a CdSeTe alloy into a ~3 µm absorber layer. This work presents the close-space sublimation fabrication of thin, 1.5 µm CdSeTe/CdTe bilayer devices using an automated in-line vacuum deposition system. The thin bilayer structure and fabrication technique minimize deposition time, increase device efficiency, and facilitate future thin absorber-based device architecture development. Three fabrication parameters appear to be the most impactful for optimizing thin CdSeTe/CdTe absorber devices: substrate preheat temperature, CdSeTe:CdTe thickness ratio, and CdCl2 passivation. For proper sublimation of the CdSeTe, the substrate temperature prior to deposition must be ~540 °C (higher than that for CdTe) as controlled by dwell time in a preheat source. Variation in the CdSeTe:CdTe thickness ratio reveals a strong dependence of device performance on this ratio. The optimal absorber thicknesses are 0.5 µm CdSeTe/1.0 µm CdTe, and non-optimized thickness ratios reduce efficiency through back-barrier effects. Thin absorbers are sensitive to CdCl2 passivation variation; a much less aggressive CdCl2 treatment (compared to thicker absorbers) regarding both temperature and time yields optimal device performance. With optimized fabrication conditions, CdSeTe/CdTe increases device short-circuit current density and photoluminescence intensity compared to single-absorber CdTe. Additionally, an in-line close-space sublimation vacuum deposition system offers material and time reduction, scalability, and attainability of future ultra-thin absorber architectures.

Improving inpatient pneumococcal and influenza vaccination rates.

Since 2004, pharmacists at the University of Wisconsin Hospital and Clinics have screened all adult inpatients for pneumococcal and influenza vaccination. Rates of screening patients improved to nearly 100% between 2004 and 2009, but the rate of actual administration of the vaccines hovered around 45%. A review of the process identified failure modes. This prompted a collaborative effort between pharmacy and nursing for improvement that focused on ensuring that the ordered vaccinations were actually administered. The rates of administration improved from approximately 45% in June 2009 to approximately 78% by mid-2010.