InP Nanowire Array Solar Cells Achieving 13.8% Efficiency by Exceeding the Ray Optics Limit.

Solid State Physics, Lund University, Box 118, 22100 Lund, Sweden.
Science (Impact Factor: 31.48). 01/2013; DOI: 10.1126/science.1230969
Source: PubMed

ABSTRACT Photovoltaics based on nanowire arrays could reduce cost and materials consumption compared to planar devices, but have exhibited low efficiency of light absorption and carrier collection. We fabricated a variety of millimeter-sized arrays of p-i-n doped InP nanowires and found that the nanowire diameter and the length of the top n-segment were critical for cell performance. Efficiencies up to 13.8% (comparable to the record planar InP cell) were achieved using resonant light trapping in 180-nanometer-diameter nanowires that only covered 12% of the surface. The share of sunlight converted into photocurrent (71%) was six times the limit in a simple ray optics description. Furthermore, the highest open circuit voltage of 0.906 volt exceeds that of its planar counterpart, despite about 30 times higher surface-to-volume ratio of the nanowire cell.

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Jesper Wallentin