What are quantum dots?

Quantum dots are man-made semiconductor nanocrystals with distinct optical and electronic capabilities, including the capacity to transport electrons and emit light of various colors depending on their size and structure.

The first quantum dots (QDs) were created in 1981 at the Vavilov State Optical Institute, followed by Louis E. Brus' team at Bell Labs in 1983, when the phrase "quantum dot" was coined. Moungi Bawendi, Louis E. Brus, and Alexey Ekimov were awarded the Nobel Prize in Chemistry 2023 for their work on the discovery and synthesis of quantum dots.

Why are quantum dots important?

These synthetic semiconductor nanoparticles have numerous uses, including single-electron transistors, solar cells, LEDs, lasers, single-photon sources, second-harmonic generation, quantum computing, cell biology research, microscopy and medical imaging.

Because QDs are both photo-active (photoluminescent) and electro-active (electroluminescent) and have unique physical features, TV screens are common applications. They will most likely be important to next-generation displays. Samsung and LG introduced QLED TVs in 2015, and a few other firms soon followed.

Quantum dots are very useful in optical applications because of their vivid, pure colors, ability to emit a rainbow of colors, their high-efficiency, longer lifetimes and high extinction coefficients. QD-based materials outperform organic luminescent materials used in organic light-emitting diodes (OLEDs) in terms of color purity, longevity, production costs and power consumption.

Another significant advantage is that QDs can be deposited on almost any substrate, allowing for printable and flexible quantum dot displays of all sizes.

Tuning the size of QDs has several possible applications. Larger QDs, for example, have a greater red spectrum shift than smaller dots and exhibit less obvious quantum features. In contrast, smaller particles enable the use of more complicated quantum phenomena.

Additionally, QDs have been proposed as active components for thermoelectrics and as qubit implementations for quantum information processing. High-quality  QDs have a narrow/symmetric emission spectrum and broad excitation profiles, making them ideal for optical encoding and multiplexing applications.

Compared to higher-dimensional structures, QDs, which are zero-dimensional, contain a more concentrated density of states. Electronic devices can function at higher speeds because of their small size, which also reduces the distance that electrons must travel compared to larger particles.

Applications capable of utilizing these special electronic characteristics include solar cells, transistors, ultrafast all-optical switches and logic gates and quantum computing.