Si nanowire solar cells: Principles, device types, future aspects, and challenges

Dream of low-cost and high-efficiency Si solar cells is going to see daylight through the advent of Si nanowire (SiNW)-based solar cells due to the unique three-dimensional structures over planar solar cells. SiNW arrays are designed to increase light absorption beyond the bandgap limitations by efficient light trapping and antireflection. Junction fabrication technique has made it possible to make very short carrier collection pathways that provide the opportunity to use lower-grade Si material and also reduce material quantity while maintaining highquality photovoltaic performance. Additionally, peeling off and transfer of SiNW arrays or in situ growth of SiNWs directly on low-cost substrates can introduce another major cost reduction in photovoltaic industry. This chapter focuses on the recent progress and photovoltaic aspects of the state-of-the-art technologies for SiNW-based solar cell fabrication. Fabrication and performance of different types of photovoltaic devices based on SiNWs are summarized. The challenges face by the fabrication processes and drawbacks of these kinds of devices due to the use of SiNWs are also discussed. Several possible new techniques to face the problems of this emerging field are also included.