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 CsPbI₃perovskite 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.

Solution-processed materials, including halide perovskites and newly discovered MXenes, are emerging as promising candidates for next-generation optoelectronic devices. Here, large-scale image sensor arrays (1250 pixels) based on a MXene/perovskite/MXene structure are demonstrated by utilizing top-down techniques, i.e. spin-coating and laser-scribing. The work allows processing perovskite and MXene materials into sub-millimeter photodetector arrays on a large scale with potential for further down-scaling of the device dimensions. The favorable energy level alignment and resonance enhancement of such materials enable efficient charge transfer and detection up to the near infrared region. A high responsivity of 84.77 A W⁻¹, a high specific detectivity of 3.22 × 10¹² Jones, and a large linear dynamic range (LDR) up to 82 dB in a broadband wavelength range from visible to near-infrared are achieved. In addition, the device shows an excellent image-capture capability under near infrared illumination. Given the tunability and compatibility with complementary metal–oxide–semiconductors (CMOS), the method potentially promotes the development of low-cost, high-performance, and large format photodetector arrays.

Heterogeneous integration of III–V quantum dots on Si substrates for infrared photodetection is reviewed, focusing on direct epitaxial growth and bonding techniques over the last few years.