Milestone-Proposal:Quantum Dots

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Docket #:2024-10

This proposal has been submitted for review.

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To the proposer’s knowledge, is this achievement subject to litigation? No

Is the achievement you are proposing more than 25 years old? Yes

Is the achievement you are proposing within IEEE’s designated fields as defined by IEEE Bylaw I-104.11, namely: Engineering, Computer Sciences and Information Technology, Physical Sciences, Biological and Medical Sciences, Mathematics, Technical Communications, Education, Management, and Law and Policy. Yes

Did the achievement provide a meaningful benefit for humanity? Yes

Was it of at least regional importance? Yes

Has an IEEE Organizational Unit agreed to pay for the milestone plaque(s)? Yes

Has the IEEE Section(s) in which the plaque(s) will be located agreed to arrange the dedication ceremony? Yes

Has the IEEE Section in which the milestone is located agreed to take responsibility for the plaque after it is dedicated? Yes

Has the owner of the site agreed to have it designated as an IEEE Milestone? Yes

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Year or range of years in which the achievement occurred:

1982

Title of the proposed milestone:

Quantum Dots, 1982

Plaque citation summarizing the achievement and its significance; if personal name(s) are included, such name(s) must follow the achievement itself in the citation wording: Text absolutely limited by plaque dimensions to 70 words; 60 is preferable for aesthetic reasons.

Semiconductor nanocrystals, known as quantum dots (QDs), possess unique optical and electronic properties between bulk semiconductors and discrete atoms. In 1982, Bell Labs Researcher Louis E. Brus synthesized and experimentally demonstrated size-dependent quantum effects in particles that floated freely in a solution, and then developed a theoretical framework to explain the size-dependent electronic structure and optical properties. This work helped launch nanotechnology applications in electronics, photonics, and biotechnology.

200-250 word abstract describing the significance of the technical achievement being proposed, the person(s) involved, historical context, humanitarian and social impact, as well as any possible controversies the advocate might need to review.

Louis E. Brus, a former Bell Labs researcher, was awarded the 2023 Nobel Prize in Chemistry on December 10, 2023 for “the discovery and synthesis of quantum dots.” Brus shared the prize with Alexei Ekimov and Moungi Bawendi for the development of these nanoparticles so tiny that their size determines their properties. These smallest components of nanotechnology now spread their light from televisions, LED lamps and solar cells, and they can also guide surgeons when they remove tumor tissue, among many other uses in cell biology research, microscopy and medical imaging. In its October 4 announcement, the Royal Swedish Academy of Sciences cited Brus for being “the first scientist in the world to prove size-dependent quantum effects in particles floating freely in a fluid.” Quantum dots are now used in a very wide array of optoelectronic applications due to their high efficiency and ease of tuning. They illuminate computer monitors and television screens based on QLED technology. They also add nuance to the ligh

IEEE technical societies and technical councils within whose fields of interest the Milestone proposal resides.

Photonics, Solid-State Circuits

In what IEEE section(s) does it reside?

North Jersey

IEEE Organizational Unit(s) which have agreed to sponsor the Milestone:

IEEE Organizational Unit(s) paying for milestone plaque(s):

Unit: North Jersey Section
Senior Officer Name: Emad Farag

IEEE Organizational Unit(s) arranging the dedication ceremony:

Unit: North Jersey Section
Senior Officer Name: Emad Farag

IEEE section(s) monitoring the plaque(s):

IEEE Section: North Jersey Section
IEEE Section Chair name: Emad Farag

Milestone proposer(s):

Proposer name: Theodore Sizer
Proposer email: Proposer's email masked to public

Please note: your email address and contact information will be masked on the website for privacy reasons. Only IEEE History Center Staff will be able to view the email address.

Street address(es) and GPS coordinates in decimal form of the intended milestone plaque site(s):

600 Mountain Avenue, Murray Hill, NJ 07974 40.684031, -74.401783

Describe briefly the intended site(s) of the milestone plaque(s). The intended site(s) must have a direct connection with the achievement (e.g. where developed, invented, tested, demonstrated, installed, or operated, etc.). A museum where a device or example of the technology is displayed, or the university where the inventor studied, are not, in themselves, sufficient connection for a milestone plaque.

Please give the address(es) of the plaque site(s) (GPS coordinates if you have them). Also please give the details of the mounting, i.e. on the outside of the building, in the ground floor entrance hall, on a plinth on the grounds, etc. If visitors to the plaque site will need to go through security, or make an appointment, please give the contact information visitors will need. Intention is to have the plaque just outside the main entrance to the Nokia Bell Labs facility in Murray Hill, NJ. Is both a corporate building and an Historic Site as other historical markers from IEEE are already on site both inside and outside the building.

Are the original buildings extant?

Yes

Details of the plaque mounting:

Outside the building on a rock or other permanent structure.

How is the site protected/secured, and in what ways is it accessible to the public?

The plaque will be prior to entering the building and thus there is no need to pass through security.

Who is the present owner of the site(s)?

Nokia America

What is the historical significance of the work (its technological, scientific, or social importance)? If personal names are included in citation, include detailed support at the end of this section preceded by "Justification for Inclusion of Name(s)". (see section 6 of Milestone Guidelines)

Justification for Inclusion of Names" The researcher that performed the research experiments at Bell Labs that demonstrated the unique and fundamental quantum effects was Louis Brus and thus it is appropriate that he is named. Brus was the lead researcher and there are no other names that should be considered for inclusion. This experiment was similarly recognized by the Nobel Committee at which he received the Nobel Prize for this work.

Quantum Dots

Quantum dots are nanoscale semiconductor crystals that exhibit size-dependent optical and electronic properties due to quantum confinement effects. Their discovery and development in the 1980s and 1990s helped launch the field of nanotechnology and led to numerous applications in electronics, photonics, and biotechnology. In 2023, the Nobel Prize in Chemistry was awarded to Alexei Ekimov, Louis Brus, and Moungi Bawendi for their pioneering work on quantum dots.

History and Discovery

Theoretical Foundations

The concept of quantum confinement in small particles was first proposed theoretically in the 1930s by physicist Herbert Fröhlich, who explored the consequences of the Schrödinger equation for nanoscale systems[1]. In the following decades, researchers further developed theories of quantum size effects, but experimental demonstration remained elusive until the 1980s.

Early Experimental Work In 1979 Soviet physicist Alexei Ekimov began studying semiconductor-activated glasses at the Vavilov State Optical Institute[1]. Working with theorist Alexander Efros, Ekimov discovered that copper chloride nanocrystals in glass exhibited size-dependent optical properties consistent with quantum confinement effects. This work, published in 1981, represented one of the first experimental demonstrations of quantum dots[2].

Louis Brus and Colloidal Quantum Dots In 1983 American chemist Louis Brus, working at Bell Labs, independently discovered quantum confinement effects in colloidal semiconductor nanocrystals suspended in solution[3]. Brus developed a theoretical framework to explain the size-dependent electronic structure and optical properties of these "colloidal quantum dots."

In a seminal 1983 paper, Brus reported the observation of size-dependent absorption spectra in colloidal suspensions of cadmium sulfide (CdS) nanocrystals[4]. He demonstrated that as the particle size decreased below about 50 Å, the absorption edge shifted to higher energies due to quantum confinement of electrons and holes.

Brus went on to develop a simple effective mass model to describe the electronic states of quantum dots[5]. This model, sometimes called the "particle-in-a-sphere" model, provided a quantitative explanation for the blue shift of the absorption edge with decreasing particle size: ΔE ≈ h²π²/2R²(1/me + 1/mh) - 1.8e²/εR where ΔE is the shift in bandgap energy, R is the particle radius, me and mh are the effective masses of electrons and holes, and ε is the dielectric constant. This is known as the Brus equation.

This theoretical framework, along with Brus's experimental demonstrations, laid the foundation for understanding and manipulating the electronic and optical properties of quantum dots. It also sparked intense research interest in colloidal semiconductor nanocrystals throughout the 1980s and beyond.

Moungi Bawendi and Synthesis Breakthroughs While the discovery of quantum confinement effects in semiconductor nanocrystals opened up exciting possibilities, early synthetic methods produced quantum dots with broad size distributions and poor optical properties. This limited their potential applications and made it difficult to study their fundamental properties.

In 1987 Moungi Bawendi spent a summer at Bell Labs working with Louis Brus and colleagues as a summer intern when he became aware of the new exciting discoveries in quantum confinement. Following his PhD in Chemistry from the University of Chicago, he returned as a Postdoctoral Fellow at Bell Labs to continue the research interaction.

By 1993 Bawendi had moved back to academia to as a young professor at MIT and made a major breakthrough in quantum dot synthesis[6]. Bawendi and his team developed a hot-injection method for synthesizing high-quality cadmium selenide (CdSe) quantum dots with narrow size distributions and high fluorescence quantum yields.

The key innovation was the rapid injection of organometallic precursors into a hot coordinating solvent, which led to a short burst of nucleation followed by slow growth. This temporal separation of nucleation and growth allowed for precise control over particle size and size distribution. Bawendi's synthesis method produced nearly monodisperse quantum dots with size distributions of less than 5% standard deviation. These high-quality nanocrystals exhibited sharp optical absorption features and bright, narrow fluorescence emission. The ability to synthesize uniform quantum dots with well-defined optical properties was crucial for both fundamental studies and practical applications.

In subsequent work, Bawendi and colleagues further refined synthesis methods and developed techniques for producing quantum dots with various compositions, shapes, and structures (e.g., core-shell quantum dots)[7]. These advances dramatically expanded the toolkit of available quantum dot materials and properties.

Applications and Impact The work of Ekimov, Brus, Bawendi, and others laid the foundation for a wide range of quantum dot applications: 1. Displays and Lighting: Quantum dots are used in QLED displays and as phosphors in LED lighting to produce vivid colors with high efficiency[8]. 2. Biological Imaging: The size-tunable, bright fluorescence of quantum dots makes them valuable probes for cellular and molecular imaging[9]. 3. Solar Cells: Quantum dots can be used to harvest light in photovoltaic devices, potentially enabling more efficient solar cells[10]. 4. Lasers: Quantum dot lasers offer advantages in terms of temperature stability and spectral purity[11]. 5. Single-Photon Sources: Individual quantum dots can act as sources of single photons for quantum information applications[12].

Nobel Prize in Chemistry 2023

On October 4, 2023, the Royal Swedish Academy of Sciences announced that the Nobel Prize in Chemistry would be awarded jointly to Alexei Ekimov, Louis Brus, and Moungi Bawendi "for the discovery and synthesis of quantum dots"[13]. The Nobel Committee cited the trio's work as having "planted an important seed for nanotechnology" and highlighted the wide-ranging applications of quantum dots, from television displays to medical imaging[14].

In awarding the prize, the committee recognized three key contributions: 1. Ekimov's discovery of size-dependent quantum effects in copper chloride nanoparticles in glass in the early 1980s. 2. Brus's demonstration of size-dependent quantum effects in colloidal nanoparticles and development of theoretical models to explain these effects in the mid-1980s. 3. Bawendi's revolutionary synthesis method for producing high-quality, monodisperse quantum dots in the early 1990s.

The recognition of quantum dots with the Nobel Prize underscores their importance as a fundamental discovery in nanoscience and their significant technological impact. It also highlights the often long path from initial scientific discovery to practical applications and widespread recognition.

Conclusion The discovery and development of quantum dots represents a major achievement in nanoscience and materials chemistry. From early theoretical predictions to experimental demonstrations and synthetic breakthroughs, the work of Ekimov, Brus, Bawendi, and many others opened up a new realm of size-tunable electronic and optical properties in semiconductor materials. Quantum dots have not only provided a powerful platform for studying quantum confinement effects but have also found widespread applications in areas ranging from consumer electronics to biomedical imaging. The awarding of the 2023 Nobel Prize in Chemistry for this work recognizes both its fundamental scientific importance and its transformative technological impact.

Footnotes

[1] Robinson, J. (2023). The quantum dot story. Chemistry World.

[2] Ekimov, A.I. & Onushchenko, A.A. (1981). Quantum size effect in three-dimensional microscopic semiconductor crystals. JETP Lett. 34, 345-349.

[3] Rossetti, R., Nakahara, S. & Brus, L.E. (1983). Quantum size effects in the redox potentials, resonance Raman spectra, and electronic spectra of CdS crystallites in aqueous solution. J. Chem. Phys. 79, 1086-1088.

[4] Rossetti, R. & Brus, L. (1982). Electron-hole recombination emission as a probe of surface chemistry in aqueous cadmium sulfide colloids. J. Phys. Chem. 86, 4470-4472.

[5] Brus, L.E. (1984). Electron–electron and electron‐hole interactions in small semiconductor crystallites: The size dependence of the lowest excited electronic state. J. Chem. Phys. 80, 4403-4409.

[6] Murray, C.B., Norris, D.J. & Bawendi, M.G. (1993). Synthesis and characterization of nearly monodisperse CdE (E = sulfur, selenium, tellurium) semiconductor nanocrystallites. J. Am. Chem. Soc. 115, 8706-8715.

[7] Dabbousi, B.O., Rodriguez-Viejo, J., Mikulec, F.V., Heine, J.R., Mattoussi, H., Ober, R., Jensen, K.F. & Bawendi, M.G. (1997). (CdSe)ZnS Core−Shell Quantum Dots: Synthesis and Characterization of a Size Series of Highly Luminescent Nanocrystallites. J. Phys. Chem. B 101, 9463-9475.

[8] Shirasaki, Y., Supran, G.J., Bawendi, M.G. & Bulović, V. (2013). Emergence of colloidal quantum-dot light-emitting technologies. Nat. Photonics 7, 13-23.

[9] Michalet, X., Pinaud, F.F., Bentolila, L.A., Tsay, J.M., Doose, S., Li, J.J., Sundaresan, G., Wu, A.M., Gambhir, S.S. & Weiss, S. (2005). Quantum dots for live cells, in vivo imaging, and diagnostics. Science 307, 538-544.

[10] Kamat, P.V. (2013). Quantum dot solar cells. Semiconductor nanocrystals as light harvesters. J. Phys. Chem. C 112, 18737-18753.

[11] Klimov, V.I., Mikhailovsky, A.A., Xu, S., Malko, A., Hollingsworth, J.A., Leatherdale, C.A., Eisler, H.J. & Bawendi, M.G. (2000). Optical gain and stimulated emission in nanocrystal quantum dots. Science 290, 314-317.

[12] Michler, P., Kiraz, A., Becher, C., Schoenfeld, W.V., Petroff, P.M., Zhang, L., Hu, E. & Imamoglu, A. (2000). A quantum dot single-photon turnstile device. Science 290, 2282-2285.

[13] The Royal Swedish Academy of Sciences. (2023). The Nobel Prize in Chemistry 2023. Press release.

[14] Optics.org. (2023). Quantum dot developers win $1M Nobel Prize in Chemistry.

What obstacles (technical, political, geographic) needed to be overcome?

To observe and exploit the unique nature of quantum confined material understanding of the theoretical basis and experimental verification was essential. To translate this into practice, however, the material needed to be of uniform size to exploit the effects at unique wavelengths. Thus, the key obstacle was to produce and isolate the nanoparticles at a semi-uniform dimension. The first effective manufacture of quantum dots with exceptional uniformity was by Moungi Bawendi at MIT.

What features set this work apart from similar achievements?

Fundamental discovery of the performance of quantum size limited semiconductor dots and their application, as recognized by the Nobel Prize. While this is extension of knowledge in the fundamentals of physics and thus a worthy milestone on its own, the aspect which is exceptional is the exploitation of this effect to develop many unique capabilities in a wide variety of application spaces.

Why was the achievement successful and impactful?

The discovery of size dependent quantum effects in suspended particles extended our knowledge of physics. These unique effects were later used with positive impact in myriad applications including lasers, novel semiconductor devices, and displays.

Supporting texts and citations to establish the dates, location, and importance of the achievement: Minimum of five (5), but as many as needed to support the milestone, such as patents, contemporary newspaper articles, journal articles, or chapters in scholarly books. 'Scholarly' is defined as peer-reviewed, with references, and published. You must supply the texts or excerpts themselves, not just the references. At least one of the references must be from a scholarly book or journal article. All supporting materials must be in English, or accompanied by an English translation.

Brus, L.E. "Electron-electron and electron-hole interactions in small semiconductor crystallites: The size dependnece of the lowest excited electronic state" J. Chem Phys 80, 4403-4409 (1984)
Brus, L.E. "A simple model for the ionization potential, electron affinity, and aqueous redox potentials of small semionductor crystallites" J. Chen Phys 79, 5566-5571 (1983)
Rossetti R., Nakahara, S, Brus, L.E. "Quantum size effects in the redox potentials, resonance Raman spectra, and electronic spectra of CdS crystallites in aqueous solution" J. Chem. Phys 79, 1086, 1088 (1983)
"The Quantum Dot Story" Chemistry World, 11 October 2023
"Quantum dot developers win $1M Nobel Prize in Chemistry" Photonics World 5 Oct 2023

Supporting materials (supported formats: GIF, JPEG, PNG, PDF, DOC): All supporting materials must be in English, or if not in English, accompanied by an English translation. You must supply the texts or excerpts themselves, not just the references. For documents that are copyright-encumbered, or which you do not have rights to post, email the documents themselves to ieee-history@ieee.org. Please see the Milestone Program Guidelines for more information.

Please email a jpeg or PDF a letter in English, or with English translation, from the site owner(s) giving permission to place IEEE milestone plaque on the property, and a letter (or forwarded email) from the appropriate Section Chair supporting the Milestone application to ieee-history@ieee.org with the subject line "Attention: Milestone Administrator." Note that there are multiple texts of the letter depending on whether an IEEE organizational unit other than the section will be paying for the plaque(s).

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