Student Thesis Prize Awards

2023-2024 Call For Nomination Is Now CLOSED

The Kavli Energy NanoScience Institute (ENSI) invites Kavli ENSI faculty to submit nominations for the 2023-2024 Thesis Prize.  Nominations will be reviewed based on the quality of the work, publication status, strength of supporting letters and relevance of the thesis to the Kavli ENSI mission. The recipient will be recognized with a $2,000 stipend. The prize will be presented annually.

Submission Guidelines:

* Each Kavli ENSI faculty may nominate one student’s thesis, and this student may be affiliated with a non- Kavli ENSI PI.
* The Prize Committee may select up to two winners per year.
* A student is eligible if the PhD. is completed from Fall 2023 – Summer 2024.

The nomination package must include the following documents:

1. A letter of nomination from the thesis advisor signed by a Kavli ENSI Principal Investigator.
2. A copy of the nominee's CV, including publication list.
3. A one page summary of the nominee's thesist.
 All documents must be submitted as a single PDF file (in the above order) as an email attachment to <kavli-ensi@berkeley.edu>

Important Dates:

Nominations Deadline: Friday, September 13, 2024.

Notification of Decision: Between mid-October and mid-November.

The Kavli ENSI Thesis Prize Committee is pleased to announce the recipients of the best Thesis Prize.

2023-2024 Cheng Zhu

Advisor: Professor Peidong Yang, Department of Material Sciences and Engineering, Department of Chemistry

Supramolecular Assembly of Halide Perovskite Building Blocks
Cheng's thesis presents an innovative supramolecular assembly strategy for designing metal halide perovskites by manipulating metal-halide complexes. The first section highlights the construction of charge-neutral (crown ether@A)2MX6 motifs, formed from crown ethers and double perovskite A2MX6, which assemble into hexagonal single crystals. In the second part, Cheng demonstrates near-unity photoluminescence quantum yield (PLQY) blue emission from the supramolecular assembly of [HfBr6]2- octahedral centers, a less explored configuration. Notably, (18C6@K)2HfBr6 solid powders exhibit a PLQY of 96.22%. Additionally, efficient green emission (82.69% PLQY) is achieved due to the high tunability of the dumbbell structural unit. The solution-processable nature of these materials enables their use in thin film and 3D printing applications. Cheng's research further expands the supramolecular approach to the one-dimensional (1D) molecular wire regium, with potential applications in miniaturized molecular optoelectronic devices. This work paves the way for significant advancements in both supramolecular assembly and nanomaterials research.

2022-2023 Emma Vargo

Advisor: Professor Ting Xu, Department of Material Sciences and Engineering, Department of Chemistry

Translating the Advantages of Biology to Synthetic Self-Assembled Nanocomposites
Ordered structures spanning multiple length scales can produce exceptional mechanics, as found in spider silk, and beautiful optics, as seen in the photonic wings of many birds and insects. While human-engineered materials will likely never match the diversity and complexity of natural materials, similar hierarchies of hard and soft domains have been achieved using a self-assembling polymer nanocomposite system. The system is a blend of block copolymer-based supramolecules, organic small molecules, and inorganic nanoparticles. In this dissertation, different compositions and processing conditions are used to produce a variety of functional nanocomposites: barrier coatings, dielectric breakdown materials, and optical devices. More broadly, this work describes the complexity and self-regulation that emerge from blends of dissimilar building blocks. The key insight of this dissertation is a new hierarchical self-assembly approach. Unlike traditional methods, which rely on condensation or precipitation, the system forms a coarse microscopic framework at low concentrations. This allows for fast diffusion and negligible enthalpy, enabling supramolecules, small molecules, and nanoparticles to be organized into stacks of parallel layers with thicknesses of 127 nm. The self-assembly mechanism is explored using neutron scattering, X-ray photon correlation spectroscopy, and computational image analysis of electron micrographs. The multilayer coatings exhibited excellent mechanical stability, structural color, dielectric breakdown strengths, and vapor barrier properties for water and volatile organic compounds. Performance analyses revealed a convoluted relationship between blend formulation, processing, morphology, and properties. Overall, this approach offers a promising strategy for producing functional materials through entropy-driven assembly. 

2021-2022 Stefano Cestellos-Blanco

Advisor: Professor Peidong Yang, Department of Chemistry, Materials science and Engineering 

Sustainable CO2 valorization by coupling electro- and biocatalysis

Earth’s average surface temperature has risen by over 0.84 °C caused by the increase of CO2 in the atmosphere. Renewable energy generation such as solar-to-electricity conversion has been developed over the past few decades. Yet we continue to burn more fossil fuels than ever as these technologies are hampered by intermittency and the difficulty of storing harvested energy. Photosynthesis provides a blueprint for capturing and storing solar energy in chemical bonds. However, our energy demands realistically outstrip its poor solar-to-biomass efficiency and its long timescales. Cestellos-Blanco’s thesis focused on developing photosynthetic biohybrid systems which employ light harvesting semiconductor materials paired with CO 2 -consuming bacteria for the solar-driven conversion of CO 2 and N 2 to value- added chemicals and materials. These functional materials provided the “living” biocatalysts with energy which promoted CO 2 fixation with high selectivity and low activation energy. In more detail, Cestellos-Blanco explored the interface between light-active silicon nanowires and bacteria that take up electrons to power the conversion of CO 2 into acetate. Building on this, through co-culturing of different bacterial strains, a complete biomanufacturing platform was realized where acetate served as an upgradeable carbon intermediate to produce printable polymers and fertilizer. Furthermore, engineered material platforms were employed to culture bacterial biofilms for improved access to redox molecules, thus increasing the rate of CO2 fixation. Finally, Cestellos-Blanco demonstrated a novel method to convert CO2 to sugars abiotically by coupling electrocatalysis and prebiotic chemistry. These sugars could be consumed by Escherichia coli - unlocking rapid biomanufacturing of a vast array of chemical products from CO2 .

2021-2022 Nikita Hanikel

Advisor: Professor Omar Yaghi, Department of Chemistry

Atmospheric Water Harvesting with Metal–Organic Frameworks

Advancement of supplemental methods for freshwater generation is imperative to effectively address the global water shortage crisis. In this regard, extraction of the ubiquitous atmospheric moisture is a powerful strategy allowing for decentralized access to potable water. The energy requirements as well as temporal and spatial restrictions of this approach can be substantially reduced if an appropriate sorbent is integrated in the atmospheric water generator. Accordingly, Nikita’s thesis focuses on development, characterization, and practical utilization of metal–organic frameworks (MOFs) as sorbents for water capture from air. In particular, the molecule-by-molecule water uptake mechanism in the state-of-the-art water-harvesting MOF is discerned by utilizing single-crystal X-ray diffraction analysis. Equipped with this knowledge, a strategy to deliberately shape the water-harvesting properties through the multivariate approach is developed. This allows for a reduction in desorption temperature and heat, as well as tuning of the operational humidity range without compromises to water uptake capacity and hydrothermal stability. To facilitate the industrial utilization of these materials, a novel, high-yielding synthetic method is devised, which allows for kilogram-scale production of water-harvesting MOFs. Lastly, the water mobility in these materials is probed and the water diffusion mechanism is uncovered. The insights from studying the water uptake kinetics are implemented in a new and highly productive atmospheric water harvester relying on fast uptake and release cycling. The prototype is successfully deployed in the Mojave Desert, thus establishing MOF-assisted water harvesting as a viable strategy to address water scarcity in arid climates.

2020-2021 Dr. Christopher Delre

Advisor: Professor Ting Xu, Department of Materials Science and Engineering

Molecular Understanding of Enzyme Stabilization Toward Functional Enzymatic Materials

Plastics are ubiquitous, and polymer production is exponentially increasing worldwide to meet consumer demand. Yet, in the US alone, less than 10% of plastics are recycled and over 80% are landfilled after usage. These disposal methods waste vast amounts of nonrenewable energy and create harmful microplastics that leach into the environment. We have created plastics that can be efficiently composted or depolymerized in warm water by enzymes embedded inside the plastics. By manipulating biocatalysis at the molecular level, we are able to program enzymatic latency, ensuring the integrity of the plastics’ properties during manufacturing, shelf storage, and material usage. At the plastics’ end-of-life, depolymerization is then triggered from inside of the plastic by raising the temperature of the surrounding industrial compost or water. The embedded enzymes depolymerize the plastic from the polymer chain ends, which avoids the formation of microplastics and creates recyclable small molecule building blocks. Our studies offer molecular-level guidance toward pairing enzymes with polymers to achieve selective plastic depolymerization that facilitates efficient chemical recycling and composting.

2018-2019 Dr. Christian Dierks

Advisor: Professor Omar Yaghi, Department of Chemistry 

Covalent Organic Frameworks Comprising Cobalt Porphyrins for Catalytic CO2 Reduction in Water

Covalent organic frameworks (COFs) are porous crystalline extended structures comprised of molecular building blocks and stitched together through directional covalent bonds. This allows for the design and construction of 2D and 3D framework structures with atomic precision. In his dissertation, Christian Diercks has devised protocols for pre- and post synthetic functionalization of such frameworks to tailor them for electronic applications as electrocatalysts, heterojunctions, and solid state conductors. In particular, he has funcitonalized layered 2D COFs with cobalt porphyrin active sites for the electrocatalytic reduction of carbon dioxide into value-added carbon products. To optimize the performance of these catalysts he investigated structural parameters (pore size and number of active sites), electronic parameters (framework conductivity, overpotential), as well as the influence of the morphology of the catalyst. The optimized framework electrocatalysts display high turnover frequencies and high current density at low overpotential, high faradaic efficiency for product formation over competitive off-pathway reduction, and long-term stability and cyclability.

2017 - 2018 Dr. Dohyung Kim

Advisor: Professor Peidong Yang, Department of Chemistry, Materials science and Engineering 

Nanoparticle Catalysts for Chemical Valorization of Carbon Dioxide

Electrochemical or photochemical conversion of carbon dioxide to value-added products has the potential to fundamentally change our traditional ways of harvesting energy and manufacturing chemical products. Kim's thesis focuses on the use of nanoparticles as catalusts for CO2 conversion and their structural factors affecting catalytic properties are discussed. The shift in the electrocatalytic behavior of gold-copper nanoparticles by the change of compostion and atomic orderedness has been studied to illustrate the catalytic importance of structural precision down to the atomic level. The ways of interfacing nanoparticle electrocatalysts to light absorbing platforms were explored for CO2 valorization using renewable energy sources. NAnoparticles can alos be integrated with other materials such as the metal-organic frameworks or molecular complexes for the creation of a CO2 catalytic system. Mor eimportantly, the dynamic restructuring of nanoparticles was utilized to induce favorable electrocatalytic properties for CO2 to conversion multicarbon products. Overall, the works covered in the thesis not only illustrate the structural complexity of nanoscale catalytic systems but emphasize the need og having a comprehensive understanding of all facots for the development of CO2 catalysis. 

2016 - 2017 Dr. Felipe H. da Jornada

Advisor: Professor Steven G. Louie, Department of Physics  

Quasiparticle and Optical Properties of Quasi-Two-Dimensional Systems

Since the experimental isolation of graphene in 2004, there has been tremendous interest in studying quasi-2D systems. These materials are atomically thin, and display many fascinating properties not found in regular bulk materials. Their high carrier mobility, high optical absorption, and tunable electronic properties make these quasi-2D materials ideal building blocks for next-generation chips and solar-cell devices. My dissertation seeks to explain, from a fundamental physics perspective, why these quasi-2D materials behave like this. In order to give unbiased predictions of how these systems behave, we use theoretical frameworks that do not rely on experimental fitting parameters, and use supercomputers to perform calculations. We show that many of these interesting electronic and optical properties stem from the weak electronic screening in these materials, which a result of their reduced dimensionality and which often cannot be accounted for with simpler models. We also introduce new computational approaches to make these calculations much faster and more realistic, and we show, for instance, that even the substrate that holds these materials in experiments can dramatically influence the measured properties. 

2016 - 2017 Dr. Yingbo Zhao

Advisor: Professor Omar Yaghi, Department of Chemistry

Reticular Chemistry of Mesoscopic Constructs, Glasses, and Weaving Materials

Zhao’s dissertation focuses on the development of reticular chemistry, where molecular building blocks are linked into extended frameworks using strong bonds, in the context of nanomaterial design. Specifically, the dissertation advances the frontier of reticular chemistry is three aspects: (a) bringing metal-organic frameworks (MOFs) and covalent organic frameworks (COFs), the products of reticular chemistry, into nanometer size regime and integrating them into mesoscopic constructs; (b) developing reticular chemistry beyond crystalline materials and synthesizing glassy form of MOFs; (c) Designing woven frameworks where interlacing molecular threads form crystalline three-dimensional frameworks. These developments not only provide a series of porous building blocks for nanomaterial design, but also lead to energy related applications such as electrochemical carbon dioxide reduction.

2015 - 2016 Dr. Kelsey Sakimoto

Advisor: Professor Peidong Yang, Department of Chemistry, Materials science and Engineering 

Inorganic-Biological Hybrids for Solar-to-Chemical Production

Converting sunlight to chemicals in an efficient, reliable, and inexpensive manner is a grand challenge of the century. My thesis sheds some light on a potential approach, combining high efficiency semiconductor based light harvesters, and higher performance biological catalysis for CO2 fixation. This work covers the design of a bacterium that synthesizes and uses inorganic nanoparticles for photosynthesis, enabling self-replicating solar-to-chemical production. I also begin the exploration of the mechanism behind the new form of charge transfer between semiconductor and bacterium, driving the future investigations of how these new forms of life tick. These insights guide our work as we embark on version 2.0

2014 - 2015 Dr. Noah Bronstein

Advisor: Professor Paul Alivisatos, Department of Chemistry

Material and Optical Design Rules for High Performance Luminescent Solar Concentrators

 Bronstein's dissertation highlights a path to achieve high photovoltaic conversion efficiency in luminescent solar concentrators, devices which absorb sunlight with a luminescent dye and then re-emit it into a waveguide where it is ultimately collected by a photovoltaic cell. Luminescent concentrators have been studied for more than three decades as potential low-cost but not high efficiency photovoltaics. Astute application of the black body radiation law indicates that photonic design is necessary to achieve high efficiency: a reflective filter must be used to trap luminescence at all angles while allowing higher energy photons to pass through. In addition, recent advances in the synthesis of colloidal nanomaterials have created the possibility for lumophores with broad adsoption spectra, narrow-bandwidth emission, high luminescence quantum yield, tunable Stokes shifts and tunable Stokes ratios. Together , these factors allow luminescent solar concentrators to achieve the optical characteristics necessary for high efficiency. The first generation of these devices was fabricated and tested. The devices achieved the highest luminescent concentration factors yet recorded in literature while maintaining high photon collection efficiency. 

2014 - 2015 Dr. Daniel Goldman

Advisor: Professor Carlos Bustamante, Department of Chemistry

A Convenient Partnership: The Ribosome and the Nascent Chain Interact to Modulate Protein Synthesis and Folding

During translation, the ribosome reads the genetic code of the messenger RNA, adding one amino acid at a time to the nascent polypeptide. In order to carry out it's biological function, the polypeptide must fold to the native state, and the folding process can begin before translation is complete. Goldman's thesis work has focused on ribosome-nascent chain interactions that affect both the folding process and the activity of the ribosome. Using a novel optical tweezers assay, we observed folding transitions of single ribosome-bound nascent polypeptides. We found that the ribosome can modulate the kinetics of folding, guiding the protein to the native state. 

2013 - 2014  Dr. Long Ju

Advisor: Professor Feng Wang, Department of Physics

Optical Spectroscopy of Two Dimensional Graphene and Boron Nitride

 Ju's thesis describes the use of optical spectroscopy in studying the physical properties of two dimensional nano materials like graphene and hexogonal boron nitride. Compared to bulk materials, atomically thin two dimensional materials are unique in that both electronic band structure and chemical potential can be tuned in situ by electric field. Therefore optical studies in such systems greatly benefit from modern micro-facbrication technique and electric control of the material properties. This thesis demonstrated a few examples of new possibilities in material science by combining opticap spectroscopy with other experimental techniques, such as electric transport and STM measurements. These experiments are driven by important problems in 2D materials but are generally beyond the reach of each individual technique.

2013 - 2014 Dr. Ziliang Ye 

Advisor: Professor Xiang Zhang, Department of Mechanical Engineering

Probing Optical 'Dark' Effects in Artificial and Natural Nano-Structures

Ye's dissertation is devoted to study the range of fascinating optical 'dark' effects that emerge in the nanoscale and usually cannot be probed by the linear optical spectroscopy or imaging in the far field zone. The studied systems are consisted of two parts: artificlal plasmonic antennas and natural two dimensional transiiton metal dichalcogenides (TMCDs). With plasmonic antennas, I realize the classical analog of a few intriguing quantum mechanical effects, including electromagnetic induced transparency, anti-Hermitian coupling induced super-radiance, and spin Hall effect for photon. Because most of these effects only occur in the subdiffractional scale, I develop a nearfield scanning tunneling microscopy with a super-resolution to observe these 'dark' effects. In the study of 2D TMDC, I discover several excitonic states are originated from a  very large exciton binding energy in the unique 2D semiconducting material. Using another nonlinear optical probe, second harmonic generation spectroscopy, I further identify an edge response at the domain boundary of a continuous TMDC crystal synthesized by the chemical vapor deposition technique. Finally, a TMDC exciton based light emitting device is demonstrated as a practical application.