Scientists discover warm light-emitting by utilising quantum dots

 

Using ligand modified CsPbBr3 quantum dots, a research team from Chongqing University in China developed warm white light-emitting with high, efficient emission and good colour rendering index.

What impact does this have on global energy consumption?

Lighting accounts for nearly one-fifth of global electricity usage, resulting in a significant increase in carbon dioxide emissions (CO2). Solid-state white light-emitting diodes (WLEDs) are becoming the most capable illumination sources in order to lower the existing energy requirement for lighting.

Furthermore, WLEDs are a far more energy-efficient and environmentally friendly source of light than standard bulbs or fluorescent lighting sources.

What are the typical drawbacks of WLEDs?

Near-UV or blue LEDs with a coating of either down-conversion materials, such as YAG: Ce3+ phosphors, or a combination of red and green phosphors are commonly used to produce white light.

Unfortunately, due to the varying degradation rates of the blue LEDs and phosphors, WLEDs made using this technology have poor white light performance after extensive use.

Furthermore, because to the lack of red or green emission, WLEDs typically have an unacceptable high correlated colour temperature (CCT) value and a low colour rendering index (CRI 80).

As a result, an ideal white light generating system requires a light source with a CCT of between 2500 and 6500 K and a CRI of at least 80. Due to their remarkable optoelectronic capabilities, CsPbBr3 perovskite quantum dots (QDs) have been identified as one of the most promising options for WLEDs among the luminous materials discovered thus far.

How did scientists make enough WLEDs with quantum dots?

Professor Zhigang Zang of Chongqing University provides a simple technique for achieving outstanding CsPbBr3 quantum dot stability and high WLED performance by replacing the OA ligand with a shorter 2-hexyldecanoic acid (DA) ligand for CsPbBr3 quantum dots.

Even when exposed to ethanol and water, the ligand modified CsPbBr3 quantum dots had a high PLQY of 96 percent and greatly improved stability. As a result, WLEDs are used to synthesise modified CsPbBr3 quantum dots and red AgInZnS quantum dots by pairing a blue InGaN LED with a green ligand, resulting in high-quality warm white light emission.

The researchers determined that WLEDs made from modified CsPbBr3 quantum dots have good thermal performance under high driving current, indicating that they could be used in solid-state lighting.