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.