Colorful Efficient Moiré‐Perovskite Solar Cells

Abstract Light harvesting is crucial for thin‐film solar cells. To substantially reduce optical loss in perovskite solar cells (PSCs), hierarchical light‐trapping nano‐architectures enable absorption enhancement to exceed the conventional upper limit and have great potential for achieving state‐of‐the art optoelectronic performances. However, it remains a great challenge to design and fabricate a superior hierarchical light‐trapping nano‐architecture, which exhibits extraordinary light‐harvesting ability and simultaneously avoids deteriorating the electrical performance of PSCs. Herein, colorful efficient moiré‐PSCs are designed and fabricated incorporating moiré interference structures by the imprinting method with the aid of a commercial DVD disc. It is experimentally and theoretically demonstrated that the light harvesting ability of the moiré interference structure can be well manipulated through changing the rotation angle (0°–90°). The boosted short‐circuit current is credited to augment light diffraction channels, leading to elongated optical paths, and fold sunlight into the perovskite layer. Moreover, the imprinting process suppresses the trap sites and voids at the active‐layer interfaces with eliminated hysteresis. The moiré‐PSC with an optimized 30° rotation angle achieves the best enhancement of light harvesting (28.5% higher than the pristine), resulting in efficiencies over 20.17% (MAPbI₃) and 21.76% ((FAPbI₃)_1‐x (MAPbBr₃)_x).