Louis Brus (born August 10, 1943, Cleveland, Ohio, U.S.) is an American physical chemist who was awarded the 2023 Nobel Prize in Chemistry for his work in discovering and producing quantum dots, which are very small particles whose unusual quantum properties depend on their size. He shared the prize with Russian-born American physicist Alexei Ekimov and French-born American chemist Moungi Bawendi.
Brus spent his early life in Cleveland, but his father, an insurance executive, moved the family several times throughout the Midwest. He attended Shawnee Mission North High School in Roeland Park, Kansas, before enrolling at Rice University in Houston on a Naval Reserve Officers Training Corps (NROTC) scholarship. He completed his bachelor’s degree in chemical physics in 1965. After graduation, he was able to delay his active service in the United States Navy to complete a Ph.D. degree in chemical physics. Upon his graduation in 1969, he was made a lieutenant and stationed in Washington, D.C., as a science staff officer at the United States Naval Research Laboratory. After his service was completed in 1973, he served as a research technician at AT&T Bell Laboratories in Murray Hill, New Jersey, where he began to experiment with nanocrystals and semiconducting materials.
Since the 1930s, physicists and chemists have known that a material’s size has a significant effect on its properties. That is, in particles of matter a few nanometers in size (1 nanometer = 10−9 meter), quantum mechanical effects become significant. Particles of this size are called nanoparticles.
Brus’s discovery of quantum dots in late 1982 was accidental. He and his collaborators were interested in using semiconductors to drive chemical reactions. They worked with nanoparticles of cadmium sulfide (CdS) in a solution. Brus observed that the absorption spectra of newly produced CdS nanoparticles was different from those of particles that had been allowed to sit for a day. He suspected this happened because the nanoparticles grew in size. Upon measurement, new CdS nanoparticles proved to be about 4.5 nanometers across, and older (or “ripened”) CdS nanoparticles were about 12.5 nanometers across. (Ekimov had discovered quantum dots independently and had published his work in 1981, but, because Ekimov had published in a Soviet journal, Brus did not learn about his discovery until 1984.)
Brus and his group continued working on quantum dots. Bawendi was a postdoctoral fellow under Brus in the late 1980s, and later, as a professor at MIT (Massachusetts Institute of Technology), he developed a method for producing high-quality quantum dots of a consistent size. Today quantum dots are used in many applications, including in QLED (quantum-dot light-emitting diode) screens, in solar cells, and as markers in biomedical imaging.
Brus remained at Bell Laboratories until he joined the chemistry faculty at Columbia University in 1996. There he served as the scientific head of the complex films research group at the National Science Foundation’s Materials Research Science and Engineering Center from 1998 to 2008 and as codirector of the U.S. Department of Energy’s Energy Frontiers Research Center from 2009 to 2014.
Brus became an elected fellow of the American Physical Society in 1980 and of the American Academy of Arts and Sciences in 1998, and he was elected to the United States National Academy of Sciences in 2004. He was the recipient of the American Chemical Society’s Chemistry of Materials Prize in 2005 and of the Kavli Prize in Nanoscience in 2008. Brus shared the R.W. Wood Prize of the Optical Society of America (OSA, now Optica) with Russian scientist Alexander L. Efros and Ekimov in 2006 for their work with quantum dots. In addition, Brus received the National Academy of Sciences Award in Chemical Sciences in 2010 for his ongoing work with nanocrystals and investigations into the quantum effects that govern their optical properties.