Despite intense efforts, the performance of silicon nanowire (SiNW)-based solar cells remains significantly lower than what has been achieved for bulk Si or micrometer-scale wires. Dunwei Wang and colleagues, Boston College, USA, have investigated why this is.

They find that the poor performance is not a result of the nanowire morphology, but is intrinsic to how they are produced. SiNWs made by two methods, chemical growth and electroless etching (EE), were similar in morphology, dimension, crystallinity, and doping level. Yet chemically grown SiNWs had efficiencies two orders of magnitude lower than those of EE SiNWs.

The chemical growth of SiNWs was shown to introduce mid-gap traps which reduce their performance efficiency. The finding suggests that close attention should be paid to the optimization of the synthesis of SiNWs to enable them to reach their full potential for energy conversion purposes.

• Understanding the Origin of the Low Performance of Chemically Grown Silicon Nanowires for Solar Energy Conversion
  G. Yuan, K. Aruda, S. Zhou, A. Levine, J. Xie, D. Wang,
  Angew. Chem. Int. Ed. 2011.
  DOI: 10.1002/anie.201006617