Photovoltaic Counter Electrodes: An Alternative Approach to Extend Light Absorption Spectra and Enhance Performance of Dye-Sensitized Solar Cells.

If counter electrodes (CEs) could also contribute to light harvesting in dye-sensitized solar cells (DSSCs), then the power conversion efficiency (PCE) of DSSCs would be further boosted without changing the device structure. Nearly monodispersed Ag2 Se nanocrystals with a bandgap of 1.62 eV (∼765 nm) were synthesized via a one-pot process, and Ag2 Se CEs were fabricated by using a spin-coating and annealing process. Incident photon-to-current conversion efficiency and photocurrent spectra indicated that Ag2 Se CEs can generate the electricity by harvesting more visible light, which could not be absorbed by dye-sensitized photoanodes. Thus, compared to Pt CE (7.57 %), the DSSC based on Ag2 Se CE exerted a higher PCE of 8.06 %. The development of photovoltaic CEs may offer an alternative way to promote the performance and competitiveness of DSSCs.