Perovskites are a family of materials with the same basic structure that can have an impressive array of interesting properties, including unique optical properties. Metal halide perovskites offer several advantages for use as components of LEDs and displays. They are direct-bandgap semiconductor materials that possess high photoluminescence quantum yield (PL QY) reaching 100%, they have narrow and symmetric PL peaks (full width at half-maximum about 15–30 nm, which is even better than for the traditional QDs) that enables wide color gamuts and they can easily be synthesized and processed at room temperature, or vapor-processed at low temperatures (typically <180°C) using inexpensive precursors.
Perovskite materials can benefit the MicroLED industry in two ways: as materials for color conversion (using perovskite-based QDs) and in perovskite-based LED emitters. Much R&D work is taking place on both these fronts, and interest seems to be growing.
Perovskite QDs possess outstanding photoluminescence efficiency of up to 100%, high color purity and a high absorption coefficient. These materials demonstrate superb light photo- and electrical- conversion and are promising not only for applications in displays, but also UV and X-ray sensors, and lighting devices.
Perovskite QDs have a greater tolerance to imperfections than traditional metal chalcogenide quantum dots, and have excellent quantum yields of photoluminescence and high color purity that have already surpassed those of metal chalcogenide QDs. The bandgap in perovskite QDs is 3-5 times less sensitive to nanocrystal size change than in traditional quantum dots. The big advantage of this is that the optical properties of perovskite QDs are more reproducible from batch to batch in their synthesis. It is possible to scale up the production in large volumes, maintaining precise control of emission peaks (±1-3 nm) and achieving the best color purity (FWHM < 18-20 nm). The perovskite material nanocrystals are easy to synthesize in a colloidal suspension, and are also easily incorporated into optoelectronic devices using readily available processing techniques.
Perovskites also hold great promise as a platform for light-emitting diode (LED) applications. The external quantum efficiency (EQE) of perovskite LEDs (PeLEDs) has rapidly improved compared to state-of-the-art organic and quantum-dot LEDs. Using PeLEDs can also be a strategy to improve the cost burden of commercial microLEDs, as perovskite production processes are relatively low cost and simple.
Research on PeLEDs has gained strong momentum since the demonstration of room-temperature electroluminescence (EL) from halide perovskites in 2014. After only a few years of rapid development, researchers have succeeded in demonstrating external quantum efficiencies (EQEs) of over 20%, and internal quantum efficiencies (IQEs) of almost 100%. This is still an early stage effort, but a highly promising one.
As perovskite materials get ready to claim their place in the display industry, members of the display industry should keep a close eye on their development. Don’t miss out on the recent news! stay updated at Perovskite-Info and subscribe to the Perovskite-Info weekly newsletter.
