Inverse Opal Photonic Crystal Structured Bifacial‐Iridescent Efficient Perovskite Solar Cells and Modules

Colorful perovskite solar cells exhibit excellent potential for building-integrated photovoltaics (BIPVs), which increase the utilization of clean power. However, their efficiencies are lower than those of uncolored devices. Moreover, traditional mono-facial colored devices cannot satisfy diverse BIPV scenarios. Here a bifacial iridescent solar cell (BFI-SC) is developed, constructed by inverse opal (IO) perovskite photonic crystals and transparent front and rear electrodes. The developed BFI-SC exhibited bright vivid colors on both sides, which originate from the reflection at the photonic stop band of the IO perovskite photonic crystal. Moreover, this unique IO photonic crystal decreased the interfacial Fresnel reflection and generated a slow-photon effect, which increases the material light absorption and utilization to obtain high efficiency. Furthermore, the BFI-SC can harvest light from both sides, considerably enhancing the device efficiency. Thus, the BFI-SC achieved an impressive bifacial equivalent efficiency (η_eq) of 18.00%, which is the highest value achieved for the reported multicolored (or iridescent) solar cell. A larger-scale BFI-SC module is successfully assembled, achieving a champion η_eq of 12.77%. In addition, another perovskite material with an IO structure and wide-bandgap components exhibited vivid colors on both sides, indicating the universality of this coloring strategy and its independence of the perovskite components.