Remote epitaxial crystalline perovskites for ultrahigh-resolution micro-LED displays

The miniaturization of light-emitting diodes (LEDs) is pivotal in ultrahigh-resolution displays. Metal-halide perovskites promise efficient light emission, long-range carrier transport and scalable manufacturing for bright microscale LED (micro-LED) displays. However, thin-film perovskites with inhomogeneous spatial distribution of light emission and unstable surface under lithography are incompatible with the micro-LED devices. Continuous single-crystalline perovskite films with eliminated grain boundaries, stable surfaces and optical homogeneity are highly demanded for micro-LEDs, but their growth and device integration remain challenging. Here we realize the remote-epitaxy growth of crystalline perovskite films, enabling their seamless integration into micro-LEDs with a pixel size down to 4 μm. By incorporating a subnanometre graphene interlayer, we enable remote epitaxy and transfer of perovskites with relaxed strain. These micro-LEDs exhibit a high electroluminescence efficiency of 16.7% and a high brightness of 4.0 × 10⁵ cd m^-2. Such high performance stems from suppressed defects and efficient carrier transport in epitaxial perovskites with high crystallinity, relaxed strain and hundreds-of-nanometres thickness. The free-standing perovskites can be integrated with commercial electronic planes for independent and dynamic control of each pixel, thus facilitating both static image and video display. With these findings, we envision on-chip perovskite photonic sources such as ultracompact lasers and ultrafast LEDs.