Enhancement of Si-Based Solar Cell Efficiency via Nanostructure Integration

Abstract

Solar cells are considered one of the most promising clean and renewable energy sources. Si wafer-based solar cells currently dominate the photovoltaic (PV) market with over 80% of the market share, largely owing to the available and rich manufacturing processes developed for the integrated circuit industry. However, the relatively high cost of the PV modules using Si wafer solar cells compared to conventional fossil fuels-based energy restricts its wide adoption for the civil electricity supply. How to effectively lower the costs of PV modules becomes one of the most important scientific and technical topics, especially considering the current world-wide efforts to combat climate change due to the "greenhouse" gas emissions when consuming carbon-based fossil energy. Two methodologies are generally pursued to realize this goal: one is to utilize low-grade raw materials and the other is by increasing the power conversion efficiency (PCE). In this chapter, the approaches to lower the costs and enhance the PCE of the Si-based solar cells by incorporating various Si nanostructures (e.g., nanodots, nanowires, nanocones and nanoholes) are presented, with details on the preparation techniques and their optical and electrical characteristics. The possible mechanisms of PCE improvement using these Si nanostructures are discussed in terms of enhanced light absorption and photogenerated carrier collection.