Perovskite quantum dots (PQDs) have been one of the most exciting research topics recently because of their excellent photophysical properties and low cost fabrication. Besides, one can tune the emission colors of PQDs by changing the chemical compositions. In contrast, the traditional III-V or II-VI semiconductor QDs can only tune their emission colors by sieving the QD sizes. However, the PQDs which were synthesized by injection method usually show a poor crystallinity, relatively low photoluminescence quantum yield (PLQY), and poor stability. These limitations have hindered PQDs to be used in practical applications and mass productions. In order to solve these problems, Dr. Hao-Wu Lin, a Professor at National Tsing Hua University, has successfully developed an innovative spray synthesis technique to fabricate multi-color PQDs with excellent emission properties. A simple and cost-effective spray synthesis process was created to realize perovskite quantum dots with near-unity PLQYs, high color purity, excellent uniformity, and good emission stability. This process not only breaks through the previously-thought instability of PQDs, but also extends the feasibility of PQD mass production. The emission spectra of the PQDs perfectly reach the next-generation criterion of displays, Rec. 2020, which possesses an ultra-broad color gamut. Such that this technique is very appropriate to be applied to various display technologies. This technique has successfully protected by a Taiwan patent (US patent pending), and attracted broad attention from international community. Moreover, these innovative research results has been highlighted in the back cover of high-impact journal Advanced Materials.
In this research, Prof. Lin’s group utilized a novel spray synthesis method to fabricate nanometer-sized perovskite crystals. The PQDs fabricated by this process can reach near-unity PLQYs for both solutions and neat films. In addition, by adjusting the compositions of perovskite precursors, they can realize the emission wavelengths of PQDs from deep blue to near infrared, all with very high PLQYs. As the results, the PQDs are one of the most promising emitters to be utilized with MicroLEDs as next-generation display technology. Furthermore, by multidisciplinary collaborating with Prof. Chih-Sung Chuu at the department of physics, together they recently found that these PQDs also exhibit unique photophysical properties which make them promising quantum emitters at room temperature. Prof. Lin’s group believes these PQDs can one day be used in quantum computing or quantum communication without the dependency on the energy-consuming cryogenic system.
Following the rapid progresses of the display technology, from CRT, LCD, OLED, and now to MicroLED, people demand perfect displays more than ever. There’s still much room for improvement in current display technology. Although MicroLEDs have been regarded as one of the most promising technology for next-generation display, there are still many issues that needed to be solved, such as difficulty of multi-color mass transfer and poor color uniformity of CVD-fabricated dies. In this research, the emissions of PQDs show ultra-high color purity, good uniformity, high PLQYs, and good stability. As a result, they can reach wide-color-gamut, high color purity, high uniformity, and high stability display when the PQDs are applied as color-conversion layers with MicroLEDs. With such promising properties of spray-synthesized PQDs, Prof. Lin believe that these PQDs are very competitive and are widely applicable in various future optoelectronics.
Dr. Po-Hsin Huang
Department of Engineering and Technologies