Designing High-Efficiency Thin Silicon Solar Cells Using Parabolic-Pore Photonic Crystals

A flexible thin-film silicon solar cell with power conversion efficiency approaching 30% would be a game-changer for the photovoltaics industry. This dream has been considered unattainable, though, due to Si's indirect band gap. Also, silicon solar cells are typically thick, inflexible, and limited in efficiency by nonradiative charge-carrier losses in the large bulk volume of the cell. This research demonstrates how light trapping based on wave interference in photonic crystals could raise conversion efficiency to ~28%, over a large wavelength range of 300---1100 nm. This would set a new record for silicon-based photovoltaic technology.