Solar cells are an increasingly important energy source for meeting growing energy demands. Organic photovoltaics in particular have potential in this area due to their low cost and the relative abundance of their constituents. One concern with the inverted configuration (a type of OPV with increased long-term stability) is their reliance on activation by ultraviolet (UV) light. Here we examine the incorporation of a new electron transport layer (ETL) material, zinc tin oxide (ZTO), in order to assess its interaction with UV light. Current-voltage characteristics were analyzed using a 420 nm cutoff filter to control UV light exposure. ZTO proved to be an adequate alternative to ZnO when comparing photovoltaic response. However, no improvement was found in terms of UV light activation. In addition, recent works show that oxygen plasma treatment of metal oxides used for hole transport layers modifies the work function and yields higher efficiency devices. Spin cast benzyl phosphonic acid self-assembled monolayers (BPA SAMs) provide similar results without the need for plasma treatment. Here we examine the use of BPA SAMs in standard devices utilizing PV2000, a proprietary active layer blend made by Plextronics. The use of BPA SAMs on a nickel oxide hole transport layer deepened the work function significantly, yielding greater device performance.

The horizontal desalination units belonging to the humidification-dehumidification family purify water using air as a carrier gas. The temperature required for separation can vary from ambient to 99 °C so waste heat, fuel combustion, or solar collectors can drive the process. A unit in which air flows horizontally affords several advantages over similar vertical “Dewvaporation” towers (as an example), including ease of construction and potentially increased efficiency. The objective was to build and test horizontal units and identify areas of potential efficiency improvements. The desalination units consisted of: 1.) A series of aligned, corrugated, polypropylene sheets covered on the outside with absorbent, water-wettable cloth. 2.) A basin that caught saline water flowing downward from the absorbent cloth. 3.) Ten pumps to cycle the basin water back onto the cloth. 4.) An air blower on the front of the unit that drove air horizontally across the cloth, increasing the humidity of the air. 5.) A steam generator on the back of the unit producing steam that mixed with the incoming air to increase the temperature and humidity. 6) A steam box that caused the air to mix with the steam and return to flow inside the corrugations in the plastic sheets, creating a countercurrent heat exchanger as the exiting air transferred its heat to the incoming air and causing purified water to condense from the cooling, oversaturated air. The tested unit produced distillate at a rate of 0.87 gallons per hour with 13 parts per million total dissolved solids and an energy reuse factor of 2.5. Recommendations include the implementation of a continuous longitudinal pump design, a modification of the basin to accommodate top and bottom unit center dividers, increase in insulation coverage, and optimization of air flow rate.