Abstract:
Band edge effects slowing light in photonic crystals and internal scattering in disordered films can lead to amplification of light energy conversion. Inverse TiO 2 opals (i-TiO 2-o) with stop-band maxima at 560 and 700 nm were fabricated by replication of polystyrene (PS) opals, and were sensitized with Q-CdSe using successive ionic layer adsorption and reaction (SILAR) while tuning the Q-CdSe absorption to the red and the blue of the stop-band. Inverse disordered TiO 2 films with a single void size were replicated from disordered PS templates assembled from colloidal suspensions with increasing ionic strength. A significant gain in the photon-to-current conversion efficiency per adsorbed nanoparticle was measured in Se 2- electrolyte relative to nc-TiO 2 to the blue of the 700-i-TiO 2-o stop-band when sensitized with Q-CdSe with an absorbance edge at 600 nm, and reached a maximum average greater than 4-fold. An appreciable amplification in energy conversion was also measured in inverse disordered films.