MIT’s Innovative Technique Enables Precise Growth of NanoLED Arrays through Optoelectronics Nanotechnology

Researchers at MIT have developed a revolutionary technique for growing halide perovskite nanocrystals, offering precise control over their location and size. This breakthrough method eliminates the need for damaging fabrication techniques, making it possible to integrate these delicate materials into nanoscale devices.

Halide perovskites have gained significant attention for their outstanding optoelectronic properties, holding promise for applications in high-performance solar cells, light-emitting diodes, lasers, and more. While these materials have been used in thin-film or micron-sized devices, achieving integration at the nanoscale opens up new possibilities, such as on-chip light sources, photodetectors, and memristors. However, conventional fabrication and patterning techniques often damage the fragile material, making precise integration challenging.

To overcome this hurdle, MIT researchers devised a technique that allows halide perovskite nanocrystals to be grown precisely at the desired location with control to within less than 50 nanometers. The size of the nanocrystals can also be precisely controlled through this technique, as size greatly influences their characteristics. By locally growing the material with desired features, there is no need for conventional lithographic patterning, which could potentially cause damage.

The scalability, versatility, and compatibility of this technique with conventional fabrication steps enable the integration of nanocrystals into functional nanoscale devices. The researchers utilized this approach to fabricate arrays of nanoscale light-emitting diodes (nanoLEDs). These tiny crystals emit light when electrically activated and hold potential for applications in optical communication, computing, lensless microscopes, quantum light sources, and high-density, high-resolution displays for augmented and virtual reality.

Farnaz Niroui, the EE Landsman Career Development Assistant Professor of Electrical Engineering and Computer Science and senior author of the research paper, emphasized the importance of developing new engineering frameworks for integrating nanomaterials into functional nanodevices. By surpassing the traditional boundaries of nanofabrication, materials engineering, and device design, these techniques allow for the manipulation of matter at extreme nanoscale dimensions, supporting the realization of unconventional device platforms crucial for addressing emerging technological needs.

The researchers’ method involves growing halide perovskite crystals directly onto the desired surface, where nanodevices will be fabricated. They utilize a nanoscale template with small wells that contain the chemical process responsible for crystal growth. By modifying the template’s surface and the wells’ interior, they control a property called “wettability,” ensuring that the perovskite solution remains confined within the wells.

With this approach, the solution containing halide perovskite growth material is applied to the template, and as the solvent evaporates, tiny crystals form within each well. The researchers found that the shape of the wells plays a critical role in determining the nanocrystal positioning. By altering the well’s shape, nanoscale forces can be engineered to precisely place the crystals at desired locations.

Moreover, the researchers discovered that they could control the crystal size by adjusting the well size to allow more or less growth solution. To demonstrate the effectiveness of their technique, they fabricated precise arrays of nanoLEDs, which emit light at the nanopixel level. These high-density arrays have potential applications in on-chip optical communication and computing, quantum light sources, microscopy, and high-resolution displays for augmented and virtual reality.

The researchers aim to explore further applications for these miniature light sources and investigate the limits of their size, as well as effectively integrating them into quantum systems. In addition to nanoscale light sources, this process opens up opportunities for developing on-chip nanodevices based on halide perovskites.

The technique not only facilitates the study of materials at the individual nanocrystal level but also inspires researchers to investigate and fine-tune material properties for diverse applications. It offers a highly controlled and deterministic method for synthesizing individual perovskite nanocrystals on substrates, paving the way for highly efficient, nanoscale LEDs based on single nanocrystals.

The research was published in the journal Nature Communications and was supported, in part, by the National Science Foundation and the MIT Center for Quantum Engineering.

Frequently Asked Questions (FAQs) about nanocrystal growth

More about nanocrystal growth

• MIT News: Optoelectronics Nanotechnology Innovation
• Nature Communications: On-site growth of perovskite nanocrystal arrays for integrated nanodevices