A Boost For Nanowire Solar Cells

A new design of solar cells made from indium phosphide nanowires boasts an efficiency of up to 13.8%, on par with that of traditional flat solar cells (Science, DOI: 10.1126/science.1230969). The work, from Magnus T. Borgström and Jesper Wallentin at Lund University, in Sweden, and their colleagues, is a promising step for development of nanowire array photovoltaics. Those devices are potentially cheaper and more environmentally friendly than traditional flat solar cell materials. Previous nanowire solar cells were plagued by low efficiencies. Borgström’s team designed InP nanowires that are only 180 nm wide—a diameter at which theory predicts efficient light-gathering properties. The nanowires are topped with a conductive and transparent indium tin oxide coating. Arrays of the new nanowires cover only 12% of a surface, yet they convert 71% of sunlight into photocurrent. “This design should be readily scalable to wafer-sized cells and be useful for similar opto-electronic devices such as photodetectors,” the researchers write.