Microscale light-emitting diodes (micro-LEDs) are emerging as a next-generation display technology for optical communications, augmented and virtual reality, and wearable devices. Metal-halide perovskites show great potential for efficient light emission, long-range carrier transport, and scalable manufacturing, making them potentially ideal candidates for bright LED displays.

However, manufacturing thin-film perovskites suitable for micro-LED displays faces serious challenges. For example, thin-film perovskites may exhibit inhomogeneous light emission, and their surfaces may be unstable when subjected to lithography. For these reasons, solutions are needed to make thin-film perovskites compatible with micro-LED devices.

Recently, a team of Chinese researchers led by Professor WU Yuchen at the Technical Institute of Physics and Chemistry of the Chinese Academy of Sciences has made significant strides in overcoming these challenges. The team has developed a novel method for the remote epitaxial growth of continuous crystalline perovskite thin films. This advance allows for seamless integration into ultrahigh-resolution micro-LEDs with pixels less than 5 μm.

The results of their research, published in Nature Nanotechnology on Jan. 15, describe a remote epitaxial growth technique that utilizes a graphene interlayer to create continuous crystalline perovskite thin films over an area of 4 cm². This method effectively eliminates grain boundaries and achieves a pure out-of-plane crystallographic orientation.

Using these single-crystalline, freestanding perovskite thin films, the researchers achieved remarkable results for micro-LEDs, including electroluminescence efficiency of 16.1%, brightness of 4 × 105 cd m-2, and ultrahigh resolution with a pixel size of 4 μm.

The free-standing perovskites can be easily integrated with commercial electronic platforms, enabling independent and dynamic control of each pixel. This capability can be applied to both static images and video displays.

This method makes it possible to construct full-color micro-LED displays by integrating multiple perovskite components. Additionally, the perovskite films can be monolithically integrated with nanophotonic structures, such as resonant metasurfaces and photonic crystals, paving the way for the development of ultracompact photonic devices.

This work was supported by the Ministry of Science and Technology of China, the National Natural Science Foundation of China, and the Youth Innovation Promotion Association of CAS.

Remote epitaxial crystalline perovskites for ultrahigh resolution micro-LED displays (Image by Prof. WU Yuchen’s group)