Synthesising Perovskite Quantum Dots for Display Applications
OLED (organic light-emitting diode) and QLED (quantum dot light-emitting diode) are two of the most common marketing slogans used in today’s display market. We have discussed the competition between these two display paradigms at length, including the importance of self-emission leading to higher contrast in OLEDs but higher brightness when using QDs (quantum dots). This blog post will focus on a specific QD formulation known as perovskite quantum dots, and the various synthesis routes available for producing them.
What Are Perovskite Quantum Dots?
Perovskites, often referred to as metal halide perovskites (MHPs), are a group of compounds with a unique crystal structure which exhibit the chemical formula ABX3. Using perovskite formulations for quantum dots presents many advantages compared to other quantum dots, and researchers are keen to discover more.
Quantum dots are frequently used in optical applications such as light-emitting diodes (LEDs), displays such as TVs, surveillance cameras, spectroscopic instruments, and biomedical imaging. At Avantama, we have been researching the optoelectronic properties of perovskite quantum dots and their capabilities for years, as well as discovering ways of improving them and their stability.
Perovskite Quantum Dots in Displays
The advantages of using perovskite QDs in displays range from brightness to quick light reactions. Other benefits include:
- High-quality luminescence
- High quantum yield
- Vivid imagery
- Adjustable emission wavelength
- Wide excitation wavelength range
- Reduction of display size due to their small size
- Use in liquid crystal displays (LCDs), OLEDs and micro-scale LEDs (μLED)
When used in LCDs, perovskite QDs’ colour emissions can be fine-tuned by adjusting the size of the perovskite nanocrystals or mixing the halide anions. These characteristics make perovskite quantum dots the more popular choice over other technologies.
How Do You Synthesize Perovskite Quantum Dots?
Another benefit of using perovskite quantum dots is that they can be synthesised via easy and low-cost methods. The two main methods are hot injection and synthesis at room temperature, but some others may be used depending on the structure of the composites.
Hot Injection Method
For hot injection synthesis to be carried out, caesium oleate must be prepared by stirring caesium carbonate and oleic acid in 1-octadecene (ODE) at 150°C. Additionally, lead halide must be dried in ODE by heating in vacuo. When the caesium oleate solution reaches 150°C, it is injected into a flask containing lead halide reagent, stirred, and quenched in an ice water bath.
At Room Temperature
This method is initiated by dissolving head halide and caesium halide in a solvent like dimethyl sulfoxide. Then, capping ligands, such as oleylamine and oleic acid are added, while stirring the mixture with force. The next stage involves a small amount of the above mix combined with a poorer solvent to force the perovskite quantum dots to precipitate. Finally, the mixture can be separated by centrifuge to allow the quantum dots their beneficial properties of high quantum yields.
Avantama has been working on perovskite quantum dots for many years, and we are the first company in the world to solve the perovskite quantum dot stability problems. If you would like further information on perovskite quantum dots, get in touch with us today, and we’d be happy to help.