Bidirectional Voltage Regulation for Integrated Photovoltachromic Device Based on P3HT‐Electrochromic Unit and Perovskite/Organic Tandem Solar Cells

Abstract Integrated electrochromic devices powered by photovoltaic cells have evoked a lot of interest due to their promising commercial prospects. However, their application has been restricted by the voltage adaption between the self‐powered voltage and the color‐changing threshold voltage ( V t ). Herein, a strategy of bidirectional voltage regulating is proposed to develop a novel stand‐alone integrated photovoltachromic device (I‐PVCD), which integrates perovskite/organic tandem solar cells (P/O‐TSCs) to drive color‐changing process of conjugated poly(3‐hexylthiophene) (P3HT) films. To lower the driving‐voltage of electrochromic layer, C 60 is introduced to decrease the onset oxidation potential of P3HT film, and thus leading to a reduced V t of 0.70 V benefiting from the enhanced highest occupied molecular orbital level and decreased charge transfer resistance from 67.46 to 49.89 Ω. Simultaneously, PBDB‐T is utilized as the hole transport layer in the interconnecting layer of CsPbI 2 Br/PTB7‐Th:IEICO‐4F P/O‐TSC to improve its open‐circuit voltage ( V oc ) to 1.85 V. Under their synergetic merits, a I‐PVCD with a wider self‐adaptive voltage range is achieved. This device can undergo fast and reversible chromic transition from beautiful magenta to transparent only under the solar radiation, and demonstrates a coloration efficiency of 351.90 cm 2 C −1 and a switching time of 2 s besides its excellent operating reliability.