1
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Brosseau P, Jasrasaria D, Ghosh A, Seiler H, Palato S, Kambhampati P. Two-Dimensional Electronic Spectroscopy Reveals Dynamics within the Bright Fine Structure of CdSe Quantum Dots. J Phys Chem Lett 2024; 15:1702-1707. [PMID: 38316135 DOI: 10.1021/acs.jpclett.3c03378] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2024]
Abstract
Semiconductor quantum dots are characterized by a discrete excitonic structure featuring coarse as well as fine structure. The lowest fine structure states have splittings into bright-dark states which are now well confirmed by single dot spectroscopy. In contrast, the splitting of the lowest coarse exciton into bright-bright fine structure states has not been observed nor the dynamics between these states. Here, we use the unique combination of time and energy resolution of two-dimensional electronic spectroscopy to directly observe the fine structure splittings into a bright-bright doublet. These splittings are strongly size dependent, with population relaxation on the <100 fs time scale.
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Affiliation(s)
- Patrick Brosseau
- Department of Chemistry, McGill University, Montreal H3A 0G4, Canada
| | - Dipti Jasrasaria
- Department of Chemistry, University of California, Berkeley, Berkeley, California 94720-1460, United States
| | - Arnab Ghosh
- Department of Chemistry, McGill University, Montreal H3A 0G4, Canada
| | - Helene Seiler
- Department of Chemistry, McGill University, Montreal H3A 0G4, Canada
| | - Samuel Palato
- Department of Chemistry, McGill University, Montreal H3A 0G4, Canada
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2
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Weaver H, Went CM, Wong J, Jasrasaria D, Rabani E, Atwater HA, Ginsberg NS. Detecting, Distinguishing, and Spatiotemporally Tracking Photogenerated Charge and Heat at the Nanoscale. ACS Nano 2023; 17:19011-19021. [PMID: 37721430 PMCID: PMC10569093 DOI: 10.1021/acsnano.3c04607] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/23/2023] [Accepted: 09/13/2023] [Indexed: 09/19/2023]
Abstract
Since dissipative processes are ubiquitous in semiconductors, characterizing how electronic and thermal energy transduce and transport at the nanoscale is vital for understanding and leveraging their fundamental properties. For example, in low-dimensional transition metal dichalcogenides (TMDCs), excess heat generation upon photoexcitation is difficult to avoid since even with modest injected exciton densities exciton-exciton annihilation still occurs. Both heat and photoexcited electronic species imprint transient changes in the optical response of a semiconductor, yet the distinct signatures of each are difficult to disentangle in typical spectra due to overlapping resonances. In response, we employ stroboscopic optical scattering microscopy (stroboSCAT) to simultaneously map both heat and exciton populations in few-layer MoS2 on relevant nanometer and picosecond length- and time scales and with 100-mK temperature sensitivity. We discern excitonic contributions to the signal from heat by combining observations close to and far from exciton resonances, characterizing the photoinduced dynamics for each. Our approach is general and can be applied to any electronic material, including thermoelectrics, where heat and electronic observables spatially interplay, and it will enable direct and quantitative discernment of different types of coexisting energy without recourse to complex models or underlying assumptions.
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Affiliation(s)
- Hannah
L. Weaver
- Department
of Physics, University of California, Berkeley, California 94720, United States
| | - Cora M. Went
- Department
of Physics, California Institute of Technology, Pasadena, California 91125, United States
| | - Joeson Wong
- Department
of Applied Physics and Materials Science, California Institute of Technology, Pasadena, California 91125, United States
| | - Dipti Jasrasaria
- Department
of Chemistry, University of California, Berkeley, California 94720, United States
| | - Eran Rabani
- Department
of Chemistry, University of California, Berkeley, California 94720, United States
- Materials
Sciences Division, Lawrence Berkeley National
Laboratory, Berkeley, California 94720, United States
- The
Sackler Center for Computational Molecular and Materials Science, Tel Aviv University, Tel Aviv, 69978, Israel
| | - Harry A. Atwater
- Department
of Applied Physics and Materials Science, California Institute of Technology, Pasadena, California 91125, United States
| | - Naomi S. Ginsberg
- Department
of Physics, University of California, Berkeley, California 94720, United States
- Department
of Chemistry, University of California, Berkeley, California 94720, United States
- Materials
Sciences Division, Lawrence Berkeley National
Laboratory, Berkeley, California 94720, United States
- Molecular
Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
- Kavli
Energy NanoScience Institute, Berkeley, California 94720, United States
- STROBE
NSF Science & Technology Center, Berkeley, California 94720, United States
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3
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Clune R, Das A, Jasrasaria D, Rossomme E, Cohen O, Baranger AM. Development of a Week-Long Mathematics Intervention for Incoming Chemistry Graduate Students. J Chem Educ 2023; 100:3291-3301. [PMID: 37720520 PMCID: PMC10501113 DOI: 10.1021/acs.jchemed.2c00915] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/18/2022] [Revised: 08/05/2023] [Indexed: 09/19/2023]
Abstract
A student-led mathematics bootcamp has been designed and implemented to help foster community building, improve confidence in mathematical skills, and provide mathematical resources for incoming physical chemistry doctoral students. The bootcamp is held immediately before the start of the first semester of graduate school and uses an active learning approach to review and practice undergraduate-level mathematics problems over 5 days in small student groups. This work includes the development and presentation of a new, publicly available mathematics curriculum for the bootcamp on select mathematics topics, including calculus, linear algebra, functions, differential equations, statistics, and coding in Python, aiming at improving students' confidence and learning experiences in graduate quantum mechanics and statistical physics courses. Surveys before and after the bootcamp showed an increase in students' confidence in problem-solving in key mathematical areas and social aspects of peer-led group learning. Qualitative and quantitative analyses demonstrate that the bootcamp reduced prior inequities in students' confidence metrics based on gender and mathematical background.
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Affiliation(s)
- Rachel Clune
- Kenneth
S. Pitzer Center for Theoretical Chemistry, University of California, Berkeley, California 94720, United States
- Department
of Chemistry, University of California, Berkeley, California 94720, United States
| | - Avishek Das
- Kenneth
S. Pitzer Center for Theoretical Chemistry, University of California, Berkeley, California 94720, United States
- Department
of Chemistry, University of California, Berkeley, California 94720, United States
| | - Dipti Jasrasaria
- Department
of Chemistry, University of California, Berkeley, California 94720, United States
| | - Elliot Rossomme
- Kenneth
S. Pitzer Center for Theoretical Chemistry, University of California, Berkeley, California 94720, United States
- Department
of Chemistry, University of California, Berkeley, California 94720, United States
- Chemical
Sciences Division, Lawrence Berkeley National
Laboratory, Berkeley, California 94720, United States
| | - Orion Cohen
- Department
of Chemistry, University of California, Berkeley, California 94720, United States
- Materials
Science Division, Lawrence Berkeley National
Laboratory, Berkeley, California 94720, United States
| | - Anne M. Baranger
- Department
of Chemistry, University of California, Berkeley, California 94720, United States
- Graduate
Group in Science and Mathematics Education, University of California, Berkeley, California 94720, United States
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4
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Lin K, Jasrasaria D, Yoo JJ, Bawendi M, Utzat H, Rabani E. Theory of Photoluminescence Spectral Line Shapes of Semiconductor Nanocrystals. J Phys Chem Lett 2023; 14:7241-7248. [PMID: 37552653 DOI: 10.1021/acs.jpclett.3c01630] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/10/2023]
Abstract
Single-molecule photoluminescence (PL) spectroscopy of semiconductor nanocrystals (NCs) reveals the nature of exciton-phonon interactions in NCs. Understanding the homogeneous spectral line shapes and their temperature dependence remains an open problem. Here, we develop an atomistic model to describe the PL spectrum of NCs, accounting for excitonic effects, phonon dispersion relations, and exciton-phonon couplings. We validate our model using single-NC measurements on CdSe/CdS NCs from T = 4 to 290 K, and we find that the slightly asymmetric main peak at low temperatures is comprised of a narrow zero-phonon line (ZPL) and acoustic phonon sidebands. Furthermore, we identify the specific phonon modes that give rise to the optical phonon sidebands. At temperatures above 200 K, the spectral line width shows a stronger dependence upon the temperature, which we demonstrate to be correlated with higher order exciton-phonon couplings. We also identify the line width dependence upon reorganization energy, NC core sizes, and shell thicknesses.
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Affiliation(s)
- Kailai Lin
- Department of Chemistry, University of California, Berkeley, Berkeley, California 94720, United States
| | - Dipti Jasrasaria
- Department of Chemistry, University of California, Berkeley, Berkeley, California 94720, United States
| | - Jason J Yoo
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02143, United States
| | - Moungi Bawendi
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02143, United States
| | - Hendrik Utzat
- Department of Chemistry, University of California, Berkeley, Berkeley, California 94720, United States
| | - Eran Rabani
- Department of Chemistry, University of California, Berkeley, Berkeley, California 94720, United States
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
- The Raymond and Beverly Sackler Center of Computational Molecular and Materials Science, Tel Aviv University, Tel Aviv 69978, Israel
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5
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Jasrasaria D, Weinberg D, Philbin JP, Rabani E. Erratum: “Simulations of nonradiative processes in semiconductor nanocrystals” [J. Chem. Phys. 157, 020901 (2022)]. J Chem Phys 2022; 157:169901. [DOI: 10.1063/5.0127467] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Dipti Jasrasaria
- Department of Chemistry, University of California, Berkeley, California 94720, USA
| | - Daniel Weinberg
- Department of Chemistry, University of California, Berkeley, California 94720, USA
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - John P. Philbin
- Harvard John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138, USA
| | - Eran Rabani
- Department of Chemistry, University of California, Berkeley, California 94720, USA
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
- The Raymond and Beverly Sackler Center of Computational Molecular and Materials Science, Tel Aviv University, Tel Aviv 69978, Israel
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6
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Jasrasaria D, Rabani E. Correction to Interplay of Surface and Interior Modes in Exciton-Phonon Coupling at the Nanoscale. Nano Lett 2022; 22:8033-8034. [PMID: 36126258 DOI: 10.1021/acs.nanolett.2c03590] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
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7
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Verbitsky L, Jasrasaria D, Banin U, Rabani E. Hybridization and deconfinement in colloidal quantum dot molecules. J Chem Phys 2022; 157:134502. [DOI: 10.1063/5.0112443] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The structural, electronic, and optical properties of CdSe/CdS core-shell colloidal quantum dot molecules, a new class of coupled quantum dot dimers, are explored using atomistic approaches. Unlike the case of dimers grown by molecular beam epitaxy, simulated strain profile maps of free-standing colloidal dimers show negligible additional strain resulting from the attachment. The electronic properties of the relaxed dimers are described within a semiempirical pseudopotential model combined with the Bethe-Salpeter equation within the static screening approximation to account for electron-hole correlations. The interplay of strain, hybridization (tunneling splitting), quantum confinement, and electron-hole binding energies on the optical properties is analyzed and discussed. The effects of the dimensions of the neck connecting the two quantum dot building blocks, as well as the shell thickness, are studied.
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Affiliation(s)
- Lior Verbitsky
- Institute of Chemistry and the Center for Nanoscience and Nanotechnology, Hebrew University of Jerusalem - Edmond J Safra Campus, Israel
| | - Dipti Jasrasaria
- Chemistry, University of California Berkeley Department of Chemistry, United States of America
| | - Uri Banin
- Hebrew University of Jerusalem, Israel
| | - Eran Rabani
- Chemistry, UC Berkeley, United States of America
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8
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Abstract
The description of carrier dynamics in spatially confined semiconductor nanocrystals (NCs), which have enhanced electron-hole and exciton-phonon interactions, is a great challenge for modern computational science. These NCs typically contain thousands of atoms and tens of thousands of valence electrons with discrete spectra at low excitation energies, similar to atoms and molecules, that converge to the continuum bulk limit at higher energies. Computational methods developed for molecules are limited to very small nanoclusters, and methods for bulk systems with periodic boundary conditions are not suitable due to the lack of translational symmetry in NCs. This perspective focuses on our recent efforts in developing a unified atomistic model based on the semiempirical pseudopotential approach, which is parameterized by first-principle calculations and validated against experimental measurements, to describe two of the main nonradiative relaxation processes of quantum confined excitons: exciton cooling and Auger recombination. We focus on the description of both electron-hole and exciton-phonon interactions in our approach and discuss the role of size, shape, and interfacing on the electronic properties and dynamics for II-VI and III-V semiconductor NCs.
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Affiliation(s)
- Dipti Jasrasaria
- Department of Chemistry, University of California, Berkeley, California 94720, USA
| | - Daniel Weinberg
- Department of Chemistry, University of California, Berkeley, California 94720, USA
| | - John P Philbin
- Harvard John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138, USA
| | - Eran Rabani
- Department of Chemistry, University of California, Berkeley, California 94720, USA
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9
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Abstract
Exciton-phonon coupling (EXPC) plays a key role in the optoelectronic properties of semiconductor nanocrystals (NCs), but a microscopic picture of EXPC is still lacking, particularly regarding the magnitude and scaling with NC size, the dependence on phonon frequency, and the role of the NC surface. The computational complexity associated with accurately describing excitons and phonons has limited previous theoretical studies of EXPC to small NCs, noninteracting electron-hole models, and/or a small number of phonon modes. Here, we develop an atomistic approach for describing EXPC in NCs of experimentally relevant sizes. We validate our approach by calculating the reorganization energies, a measure of EXPC, for CdSe and CdSe-CdS core-shell NCs, finding good agreement with experimental measurements. We demonstrate that exciton formation distorts the NC lattice primarily along the coordinates of low-frequency acoustic modes. Modes at the NC surface play a significant role in smaller NCs while interior modes dominate for larger systems.
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Affiliation(s)
- Dipti Jasrasaria
- Department of Chemistry, University of California, Berkeley, California 94720, United States
| | - Eran Rabani
- Department of Chemistry, University of California, Berkeley, California 94720, United States
- The Sackler Center for Computational Molecular and Materials Science, Tel Aviv University, Tel Aviv, Israel 69978
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
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10
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Banerjee A, Jasrasaria D, Niblett SP, Wales DJ. Crystal Structure Prediction for Benzene Using Basin-Hopping Global Optimization. J Phys Chem A 2021; 125:3776-3784. [PMID: 33881850 PMCID: PMC8279651 DOI: 10.1021/acs.jpca.1c00903] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2021] [Revised: 04/07/2021] [Indexed: 11/29/2022]
Abstract
Organic molecules can be stable in distinct crystalline forms, known as polymorphs, which have significant consequences for industrial applications. Here, we predict the polymorphs of crystalline benzene computationally for an accurate anisotropic model parametrized to reproduce electronic structure calculations. We adapt the basin-hopping global optimization procedure to the case of crystalline unit cells, simultaneously optimizing the molecular coordinates and unit cell parameters to locate multiple low-energy structures from a variety of crystal space groups. We rapidly locate all the well-established experimental polymorphs of benzene, each of which corresponds to a single local energy minimum of the model. Our results show that basin-hopping can be both an efficient and effective tool for polymorphic crystal structure prediction, requiring no a priori experimental knowledge of cell parameters or symmetry.
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Affiliation(s)
- Atreyee Banerjee
- Yusuf
Hamied Department of Chemistry, University
of Cambridge, Lensfield
Road, Cambridge CB2 1EW, United Kingdom
- Max
Planck Institute for Polymer Research, 55128 Mainz, Germany
| | - Dipti Jasrasaria
- Yusuf
Hamied Department of Chemistry, University
of Cambridge, Lensfield
Road, Cambridge CB2 1EW, United Kingdom
- Department
of Chemistry, University of California, Berkeley, California 94609, United States
| | - Samuel P. Niblett
- Yusuf
Hamied Department of Chemistry, University
of Cambridge, Lensfield
Road, Cambridge CB2 1EW, United Kingdom
- Department
of Chemistry, University of California, Berkeley, California 94609, United States
- Materials
Science Division, Lawrence Berkeley National
Laboratory, Berkeley, California 94609, United States
| | - David J. Wales
- Yusuf
Hamied Department of Chemistry, University
of Cambridge, Lensfield
Road, Cambridge CB2 1EW, United Kingdom
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11
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Yan C, Weinberg D, Jasrasaria D, Kolaczkowski MA, Liu ZJ, Philbin JP, Balan AD, Liu Y, Schwartzberg AM, Rabani E, Alivisatos AP. Uncovering the Role of Hole Traps in Promoting Hole Transfer from Multiexcitonic Quantum Dots to Molecular Acceptors. ACS Nano 2021; 15:2281-2291. [PMID: 33336575 DOI: 10.1021/acsnano.0c08158] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Understanding electronic dynamics in multiexcitonic quantum dots (QDs) is important for designing efficient systems useful in high power scenarios, such as solar concentrators and multielectron charge transfer. The multiple charge carriers within a QD can undergo undesired Auger recombination events, which rapidly annihilate carriers on picosecond time scales and generate heat from absorbed photons instead of useful work. Compared to the transfer of multiple electrons, the transfer of multiple holes has proven to be more difficult due to slower hole transfer rates. To probe the competition between Auger recombination and hole transfer in CdSe, CdS, and CdSe/CdS QDs of varying sizes, we synthesized a phenothiazine derivative with optimized functionalities for binding to QDs as a hole accepting ligand and for spectroscopic observation of hole transfer. Transient absorption spectroscopy was used to monitor the photoinduced absorption features from both trapped holes and oxidized ligands under excitation fluences where the averaged initial number of excitons in a QD ranged from ∼1 to 19. We observed fluence-dependent hole transfer kinetics that last around 100 ps longer than the predicted Auger recombination lifetimes, and the transfer of up to 3 holes per QD. Theoretical modeling of the kinetics suggests that binding of hole acceptors introduces trapping states significantly different from those in native QDs passivated with oleate ligands. Holes in these modified trap states have prolonged lifetimes, which promotes the hole transfer efficiency. These results highlight the beneficial role of hole-trapping states in devising hole transfer pathways in QD-based systems under multiexcitonic conditions.
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Affiliation(s)
- Chang Yan
- Department of Chemistry, University of California, Berkeley, California 94720, United States
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Daniel Weinberg
- Department of Chemistry, University of California, Berkeley, California 94720, United States
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Dipti Jasrasaria
- Department of Chemistry, University of California, Berkeley, California 94720, United States
| | - Matthew A Kolaczkowski
- Department of Chemistry, University of California, Berkeley, California 94720, United States
- Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Zi-Jie Liu
- Department of Chemistry, University of California, Berkeley, California 94720, United States
| | - John P Philbin
- Department of Chemistry, University of California, Berkeley, California 94720, United States
| | - Arunima D Balan
- Department of Chemistry, University of California, Berkeley, California 94720, United States
| | - Yi Liu
- Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Adam M Schwartzberg
- Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Eran Rabani
- Department of Chemistry, University of California, Berkeley, California 94720, United States
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
- The Sackler Center for Computational Molecular and Materials Science, Tel Aviv University, Tel Aviv 69978, Israel
| | - A Paul Alivisatos
- Department of Chemistry, University of California, Berkeley, California 94720, United States
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
- Department of Materials Science and Engineering, University of California, Berkeley, California 94720, United States
- Kavli Energy NanoScience Institute, Berkeley, California 94720, United States
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