Non-conformal Decoration of Semiconductor Nanowires as a Novel Route for Imparting them Stabilities Against Water- and Acid-assisted Degradation:

The aim of this project is to develop a strategy for imparting stabilities to water- and acid-assisted degradation to semiconductor nanowires useful in the fabrication of photovoltaics (Zn3P2) and thermoelectrics (Mg2Si). We anticipated that such a strategy is essential for the widespread deployment and use of nanowire-based energy conversion devices, as such devices will be exposed to rainwater during operation and use and rainwater is acidic in nature (pH of rainwater is ≈ 5.6). Our idea is to ensure that any strategy developed for imparting stabilities to semiconductor nanowires does not majorly impact their electrical (e.g., conductivity) and electronic (e.g., bandgap) properties. We also wanted to ensure that the strategy imparts stabilities to nanowires even at elevated temperatures as thermoelectrics devices operate at elevated temperatures. To operate within these constraints, we have developed a non-conformal BN decoration strategy that made the nanowires surfaces non-wettable by water and aqueous acidic solutions. The non-wettable nature ensured that the nanowires are resistant to water- and acid-assisted degradation. These non-conformal BN decorations also ensured that the bandgap of the nanowires, and the interfacial electrical conductivity between the nanowires in nanowire mats, are not altered. So far, we have demonstrated that nanowires of Zn3P2, ZnO and Mg2Si nanowires could be made very stable using this strategy.