Solid‐State Photochromic Transparent Photovoltaics with Bisthienylethene‐Based Molecules

Photochromic transparent photovoltaic is a promising candidate for developing smart windows in the building‐integrated photovoltaic field. However, most reported photochromic solar cells must employ liquid electrolyte in the device to achieve the photochromic function. Herein, solid‐state photochromic semitransparent organic photovoltaics (ST‐OPVs) based on a photochromic molecule with bisthienylethene (BTE) unit are reported. ST‐OPVs show a transmittance change of up to 6.10% under light irradiation, demonstrating a power conversion efficiency (PCE) of 5.21% and an average visible transmission of over 50%. The coloration–decoloration process is reversible under UV irradiation and thermal annealing. After five coloration–decoloration cycles, the photochromic ST‐OPVs can maintain 66.6% of the initial PCE. This work presents a promising application of photochromic molecules in ST‐OPVs, providing a feasible strategy for photochromic photovoltaics.