The University of Delaware has inched up the record for solar cell efficiency with a new device that can convert 42.8 percent of the light that strikes it into electricity. That beats the old record of 40.7 percent hit in December. The Defense Advanced Research Projects Agency, or DARPA, has been funding research to get efficiency up to 50 percent.
The cell, created by Christina Honsberg and Allan Barnett of UD, splits incoming light into three buckets: high energy, low energy, and medium energy light. The light is then directed to different materials, which then extract electrons out of the photons that make up sunlight.
Various materials (silicon, germanium, etc.) react differently to different parts of the solar spectrum. Crystalline solar cells, for instance, can currently convert 22 percent of light into electricity (without concentrators). The theoretical maximum is 29 percent sans concentration. Combining different materials into multi-junction cells or adding concentrators helps get around the limitations of the materials.