Silicon quantum dots have a bright future in bio-imaging

Semiconductors with quantum dots are a rising star in the world of photonic technologies. However, traditional quantum dots are made with metal chalcogenide nanoparticles, which are toxic. Silicon offers a promising alternative given its abundance, non-toxicity and broad photoluminescence spectral range. Wang and Tang provide a comprehensive look at the state and future of silicon quantum dot hybrid systems.

The review looks at silicon quantum dot’s optical properties, photophysical parameters, and energetics. Recent examples and applications of silicon quantum dots are also discussed along with current issues and future prospects.

Silicon quantum dot hybrids have already been used in a range of applications, such as solar cells, LEDs and solar concentrators. Notably, these hybrids also show great promise for photon upconversion, a process which combines two photons into one high energy photon. Photon upconversion is useful for technologies like high-resolution bioimaging and modern photovoltaic technologies.

“The most important future application for Si QDs will be in biology for optogenetics or phototherapy, or to detect oxygen levels in biocompatible scaffolds to make artificial tissue,” said author Ming Lee Tang.

However, some limitations to silicon quantum dots remain, including their low absorption coefficient at visible wavelengths and their high defect density at the surface, including dangling bonds. Several ideas have been proposed to resolve these issues, but more research is needed. For example, to help low absorption coefficients, organic molecules as visible light absorbers could be used.

“The investigation of Si-molecule hybrid systems is still in its infancy,” Tang said. “Detailed and systematic explorations on Si QD-molecule hybrid systems are necessary and significant for their promising applications in the future.”

Source: “Silicon quantum dot-molecule hybrid systems and their applications,” by Kefu Wang and Ming Lee Tang, Journal of Chemical Physics (2025). The article can be accessed at https://doi.org/10.1063/5.0249392 .