Polarized light is critical for a wide range of applications, but is usually generated by filtering unpolarized light, which leads to substantial energy losses and requires additional optics. Here we demonstrate the direct emission of linearly polarized light from light-emitting diodes made of CsPbI₃ perovskite nanoplatelet superlattices. The use of solvents with different vapour pressures enables the self-assembly of the nanoplatelets with fine control over their orientation (either face-up or edge-up) and therefore their transition dipole moment. As a result of the highly uniform alignment of the nanoplatelets, as well as their strong quantum and dielectric confinement, large exciton fine-structure splitting is achieved at the film level, leading to pure red light-emitting diodes with linearly polarized electroluminescence exhibiting a high degree of polarization of 74.4% without any photonic structures. This work demonstrates the potential of perovskite nanoplatelets as a promising source of linearly polarized light, opening up the development of next-generation three-dimensional displays and optical communications from a highly versatile, solution-processable system.

偏振光对于广泛的应用至关重要，但通常是通过过滤非偏振光产生的，这会导致大量的能量损失，并且需要额外的光学器件。_{在这里，我们演示了由 CsPbI 3}钙钛矿纳米片超晶格制成的发光二极管直接发射线偏振光。使用具有不同蒸气压的溶剂可以实现纳米片的自组装，并可以精细控制它们的方向（面朝上或边缘朝上）以及它们的转变偶极矩。由于纳米片的高度均匀排列，以及它们强大的量子和介电限制，在薄膜水平上实现了大的激子精细结构分裂，从而导致具有线性偏振电致发光的纯红色发光二极管表现出高偏振度为 74.4%，没有任何光子结构。这项工作展示了钙钛矿纳米片作为一种有前途的线偏振光光源的潜力，开启了从高度通用、可溶液处理的系统开发下一代三维显示器和光通信的大门。