Semitransparent Blue, Green, and Red Organic Solar Cells Using Color Filtering Electrodes

Colorful, semitransparent organic photovoltaic cells (OPVs) are increasing in demand due to their applicability in aesthetically fashioned power-generating windows. The traditional method of generating different colors in OPVs has been through employing different active materials exhibiting distinct absorption spectra. This can complicate fabrication processes for production and cause deviations in device performance among differently colored OPVs. Herein, semitransparent and colorful OPVs with a single broadband-absorbing active material of fixed thickness are demonstrated using Ag–TiO_x–Ag color filters (CFs). The CF enables the OPV to transmit spectrally pure colors with peak transmission efficiencies surpassing 25%, and allows the colors to be freely tuned without disturbing the charge transport properties such that the device performance stays consistent. The CF not only functions as an effective electrode but as a mirror for light outside of the spectral transparency window. It is shown that when compared to a transparent OPV consisting of the same active layer material and thickness, CF-integrated OPVs generate 32.38(±0.03)–34.10(±0.02)% more short-circuit current. Such results point to a simple and convenient solution to achieving spectrally pure colors, moderate transmission efficiencies, decoupled optical and charge transport properties, and enhanced charge generation relative to a transparent OPV in semitransparent, colorful power-generating windows.