Optical characterization of selectively transparent and conducting photonic crystals for use in thin crystalline silicon photovoltaics

The potential use of selectively transparent and conducting photonic crystals (STCPCs) made of ITO and silica nanoparticles as rear reflectors in 10 μm crystalline silicon (c-Si) photovoltaics (PV) have been explored. Optical simulations comparing the performance of STCPC-reflectors and aluminum reflectors have been performed. The STCPCs outperform aluminum reflectors deposited on the crystalline silicon surface, but exhibit significantly lower reflectivity than the case where a substantial silica film layer is included between the aluminum reflector and the c-Si absorber. However, solar cells using STCPCs as the rear-reflector are capable of generating a significant amount of photocurrent from rear illumination in bifacial PV. An STCPC has been fabricated on a 10 μm c-Si membrane and the reflection and transmission spectral measurements demonstrate the expected increase in absorption in the red-to-NIR range.