The article says: "The silicon-wire arrays absorb up to 96 percent of incident sunlight at a single wavelength and 85 percent of total collectible sunlight."
The trick is:
1. The "a single wavelength" limit: this is because the bandgap of semiconductor materials and typically one type of semiconductor only matches one frequency. However, sun light does not come at one frequency, and this 17% may be the portion of the that light color among the total light colors;
2. The "total collectible sunlight" spin: that really depends on how many devices for different frequencies. If there is only one device, it is ok to claim the same efficiency as that of the single frequency (i.e., 96%).
To improve solar cell efficiency, the real difficulty is to find or engineer a wide bandgap material. Any other improvements have to use adjactive "collectable".
Correct me if I am wrong, for I took the solar cell class
