Planar Coupled Nanocavities for Efficient Solar Spectrum Engineering

Abstract Tailoring the solar spectrum is critical for energy devices including solar cells and colorful radiative coolers, requiring additional photonic structures with manipulation capabilities adaptable to different application circumstances. However, existing photonic structures cannot effectively balance the trade‐offs between these energy devices' primary functionality, coloration, and visible transparency. Here, a series of planar coupled nanocavities (PCNs) are designed and fabricated, which can manipulate the solar spectrum of energy devices more versatilely than conventional planar multilayers. By judiciously designing and tailoring the coupling effect in the PCNs, the transmissive colors of the PCNs can occupy 99.9% of the sRGB area provided the benchmark for window applications is achieved (average visible transmittance, AVT > 25%), while 25.4% of the sRGB area can be covered by the reflective colors of sub‐ambient radiative coolers with PCNs. Moreover, when serving as the semitransparent electrodes of colorful organic solar cells (OSCs), the PCNs can provide a significantly larger color gamut than commonly used multilayered electrodes under different performance benchmarks. Remarkably, the PCNs can even locally break the trade‐offs between the power conversion efficiency (PCE) and AVT and electrode conductivity of the OSCs. The proposed PCNs provide a promising route for delicately tailoring the solar spectrum with simple multilayered structures.