News from industry

Solar cells that combine liquids and solids show promise for important advantages compared with all-solid cells. According to Bell Labs, developer of the liquid-junction cells, the devices are more economical than all-solid cells because they use less expensive polycrystalline materials and are more economical to make. The new cells have two electrodes immersed in a water-based solution. One of the electrodes is a semiconducting material; the other can be made of carbon or a variety of common metals. When light falls on the semiconductor, current flows from one electrode to the other via the liquid. With the polycrystalline form of cadmium selenide as the semiconductor electrode, Bell Labs has found that 5.1 percent of the light is converted to electricity. The more expensive single-crystal form of cadmium selenide gives a conversion efficiency of 7.5 percent. Chemicals in the solution for the liquid/solid cells are affected little by the conversion process. A three- to four-year life has been simulated.