Gilbert Newton Lewis was an American physical chemist and a dean of the college of chemistry at University of California, Berkeley. Lewis was best known for his discovery of the covalent bond and his concept of electron pairs; his Lewis dot structures and other contributions to valence bond theory have shaped modern theories of chemical bonding. Lewis successfully contributed to chemical thermodynamics, photochemistry, and isotope separation, and is also known for his concept of acids and bases. Lewis also researched on relativity and quantum physics, and in 1926 he coined the term "photon" for the smallest unit of radiant energy.
Quantum dots (QDs) or semiconductor nanocrystals are semiconductor particles a few nanometres in size with optical and electronic properties that differ from those of larger particles via quantum mechanical effects. They are a central topic in nanotechnology and materials science. When a quantum dot is illuminated by UV light, an electron in the quantum dot can be excited to a state of higher energy. In the case of a semiconducting quantum dot, this process corresponds to the transition of an electron from the valence band to the conductance band. The excited electron can drop back into the valence band releasing its energy as light. This light emission (photoluminescence) is illustrated in the figure on the right. The color of that light depends on the energy difference between the conductance band and the valence band, or the transition between discrete energy states when the band structure is no longer well-defined in QDs.
A potential well is the region surrounding a local minimum of potential energy. Energy captured in a potential well is unable to convert to another type of energy because it is captured in the local minimum of a potential well. Therefore, a body may not proceed to the global minimum of potential energy, as it would naturally tend to do due to entropy.
Armand Paul Alivisatos is an American chemist and academic administrator who has served as the 14th president of the University of Chicago since September 2021. He is a pioneer in nanomaterials development and an authority on the fabrication of nanocrystals and their use in biomedical and renewable energy applications. He was ranked fifth among the world's top 100 chemists for the period 2000–2010 in the list released by Thomson Reuters.
Cadmium selenide is an inorganic compound with the formula CdSe. It is a black to red-black solid that is classified as a II-VI semiconductor of the n-type. It is a pigment, but applications are declining because of environmental concerns.
A quantum dot solar cell (QDSC) is a solar cell design that uses quantum dots as the captivating photovoltaic material. It attempts to replace bulk materials such as silicon, copper indium gallium selenide (CIGS) or cadmium telluride (CdTe). Quantum dots have bandgaps that are adjustable across a wide range of energy levels by changing their size. In bulk materials, the bandgap is fixed by the choice of material(s). This property makes quantum dots attractive for multi-junction solar cells, where a variety of materials are used to improve efficiency by harvesting multiple portions of the solar spectrum.
The Nobel Prize in Chemistry is awarded annually by the Royal Swedish Academy of Sciences to scientists in the various fields of chemistry. It is one of the five Nobel Prizes established by the will of Alfred Nobel in 1895, awarded for outstanding contributions in chemistry, physics, literature, peace, and physiology or medicine. This award is administered by the Nobel Foundation, and awarded by the Royal Swedish Academy of Sciences on proposal of the Nobel Committee for Chemistry which consists of five members elected by the Academy. The award is presented in Stockholm at an annual ceremony on 10 December, the anniversary of Nobel's death.
Alexey Ekimov or Aleksey Yekimov is a Russian solid state physicist and a pioneer in nanomaterials research. He discovered the semiconductor nanocrystals known as quantum dots in 1981, while working at the Vavilov State Optical Institute. In 2023, he was awarded the Nobel Prize in Chemistry for this discovery.
The Brus equation or confinement energy equation can be used to describe the emission energy of quantum dot semiconductor nanocrystals in terms of the band gap energy Egap, Planck's constant h, the radius of the quantum dot r, as well as the effective mass of the excited electron me* and of the excited hole mh*. The equation was named after Louis E. Brus who independently discovered it a few years later.
Core–shell semiconducting nanocrystals (CSSNCs) are a class of materials which have properties intermediate between those of small, individual molecules and those of bulk, crystalline semiconductors. They are unique because of their easily modular properties, which are a result of their size. These nanocrystals are composed of a quantum dot semiconducting core material and a shell of a distinct semiconducting material. The core and the shell are typically composed of type II–VI, IV–VI, and III–V semiconductors, with configurations such as CdS/ZnS, CdSe/ZnS, CdSe/CdS, and InAs/CdSe Organically passivated quantum dots have low fluorescence quantum yield due to surface related trap states. CSSNCs address this problem because the shell increases quantum yield by passivating the surface trap states. In addition, the shell provides protection against environmental changes, photo-oxidative degradation, and provides another route for modularity. Precise control of the size, shape, and composition of both the core and the shell enable the emission wavelength to be tuned over a wider range of wavelengths than with either individual semiconductor. These materials have found applications in biological systems and optics.
Blinking colloidal nanocrystals is a phenomenon observed during studies of single colloidal nanocrystals that show that they randomly turn their photoluminescence on and off even under continuous light illumination. This has also been described as luminescence intermittency. Similar behavior has been observed in crystals made of other materials. For example, porous silicon also exhibits this affect.
Quantum dots (QDs) are semiconductor nanoparticles with a size less than 10 nm. They exhibited size-dependent properties especially in the optical absorption and the photoluminescence (PL). Typically, the fluorescence emission peak of the QDs can be tuned by changing their diameters. So far, QDs were consisted of different group elements such as CdTe, CdSe, CdS in the II-VI category, InP or InAs in the III-V category, CuInS2 or AgInS2 in the I–III–VI2 category, and PbSe/PbS in the IV-VI category. These QDs are promising candidates as fluorescent labels in various biological applications such as bioimaging, biosensing and drug delivery.
Moungi Bawendi is an American–Tunisian–French chemist. He is currently the Lester Wolfe Professor at the Massachusetts Institute of Technology. Bawendi is known for his advances in the chemical production of high-quality quantum dots. In 2023 he was awarded the Nobel Prize in Chemistry.
Marija Drndic is the Fay R. and Eugene L. Langberg Professor of Physics at the University of Pennsylvania. She works on two-dimensional materials and novel spectroscopic techniques.
Uri Banin is an Israeli nanotechnologist and physical chemist and a professor at the Hebrew University of Jerusalem, currently holding the Alfred & Erica Larisch Memorial Chair at the Institute of Chemistry. He is recognized as one of the pioneers of nanoscience in Israel.
Hedi Mattoussi is a Tunisian-American materials scientist and professor at Florida State University. His research considers colloidal inorganic nanocrystals for biological imaging and sensing. He is a Fellow of the American Physical Society, American Chemical Society and Materials Research Society.
Eran Rabani is an Israeli theoretical chemist. He is a professor of chemistry at the University of California, Berkeley, holding the Glenn T. Seaborg Chair in Physical Chemistry, and at the Tel Aviv University. Rabani serves as the director of The Sackler Center for Computational Molecular and Materials Science, and as a faculty scientist at the Lawrence Berkeley National Laboratory.
Alexander Lwowitsch Efros is a Russian physicist. Efros is the co-discoverer of semiconducting nanocrystals known as quantum dots.
Christopher Bruce Murray is the Richard Perry University Professor of Chemistry and Materials Science and Engineering at the University of Pennsylvania. He is a member of the National Academy of Engineering and a Fellow of the Materials Research Society. He was a Clarivate Citation Laureate in 2020. He is known for his contributions to quantum dots and other nanoscale materials.
William L. Wilson is a black American chemist. He serves as the Executive Director of the Center for Nanoscale Systems (CNS) at Harvard University. At Bell Labs, Wilson collaborated with 2023 Nobel Prize in Chemistry awardees, Louis Brus and Moungi Bawendi, in the early development and characterization of colloidal semi-conductor nanocrystals known as quantum dots. As an expert in holographic technologies, Wilson co-founded InPhase Technologies and served as their Chief Scientific Officer.
