Enhancing Flexible Perovskite Photovoltaic Cells and Modules Through Light-Trapping and Light-Shifting Strategies

Flexible perovskite photovoltaic devices are typically constructed on flexible polyethylene naphthalate (PEN) substrates, which exhibit near-ultraviolet absorption and high visible-light reflection, leading to significant optical losses. To address this issue, a reusable optical-management sticker tailored for flexible substrates has been proposed in this work. The sticker incorporates a light-shifting material that converts near-ultraviolet light into visible light, enabling photoelectric conversion of near-ultraviolet light. Additionally, the sticker features a light-trapping microstructure that creates a refractive index gradient from PEN to air, thereby achieving a significant anti-reflection effect. As a result, the efficiency of a flexible perovskite solar cell reached 23.05% (certified 22.46%) under 1 sun AM1.5G illumination and 36.65% (certified 34.03%) under 1000 lux artificial light illumination. Furthermore, scaling this solution to large-area modules has yielded remarkable improvements, achieving a breakthrough certified efficiency of 20.48% (aperture area 21 cm²) in flexible perovskite photovoltaic modules.