272. High-efficiency stretchable light-emitting polymers from thermally activated delayed fluorescence
Wei Liu, Cheng Zhang, Riccardo Alessandri, Benjamin T. Diroll, Yang Li, Heyi Liang, Xiaochun Fan, Kai Wang, Himchan Cho, Youdi Liu, Yahao Dai, Qi Su, Nan Li, Songsong Li, Shinya Wai, Qiang Li, Shiyang Shao, Lixiang Wang, Jie Xu, Xiaohong Zhang, Dmitri V. Talapin, Juan J. de Pablo and Sihong Wang. Accepted to Nature Materials.
Stretchable light-emitting materials are the key components for realizing skin-like displays and optical biostimulation. All the stretchable emitters reported to date, to the best of our knowledge, have been based on electroluminescent polymers that only harness singlet excitons, limiting their theoretical quantum yield to 25%. Here we present a design concept for imparting stretchability onto electroluminescent polymers that can harness all the excitons through thermally activated delayed fluorescence, thereby reaching a near-unity theoretical quantum yield. We show that our design strategy of inserting flexible, linear units into a polymer backbone can substantially increase the mechanical stretchability without affecting the underlying electroluminescent processes. As a result, our synthesized polymer achieves a stretchability of 125%, with an external quantum efficiency of 10%. Furthermore, we demonstrate a fully stretchable organic light-emitting diode, confirming that the proposed stretchable thermally activated delayed fluorescence polymers provide a path towards simultaneously achieving desirable electroluminescent and mechanical characteristics, including high efficiency, brightness, switching speed and stretchability as well as low driving voltage.
271. Understanding and controlling photothermal responses in MXenes
Burak Guzelturk, Vladislav Kamysbayev, Di Wang, Huicheng Hu, Ruiyu Li, Sarah B. King, Alexander H. Reid, Ming-Fu Lin, Xijie Wang, Donald A. Walko, Xiaoyi Zhang, Aaron M. Lindenberg, and Dmitri V. Talapin. Nano Letters 2023, 23, 7, 2677-2686
MXenes have the potential for efficient light-to-heat conversion in photothermal applications. To effectively utilize MXenes in such applications, it is important to understand the underlying nonequilibrium processes, including electron−phonon and phonon−phonon couplings. Here, we use transient electron and X-ray diffraction to investigate the heating and cooling of photoexcited MXenes at femtosecond to nanosecond time scales. Our results show extremely strong electron−phonon coupling in Ti3C2-based MXenes, resulting in lattice heating within a few hundred femtoseconds. We also systematically study heat dissipation in MXenes with varying film thicknesses, chemical surface terminations, flake sizes, and annealing conditions. We find that the thermal boundary conductance (TBC) governs the thermal relaxation in films thinner than the optical penetration depth. We achieve a 2-fold enhancement of the TBC, reaching 20 MW m−2 K−1 by controlling the flake size or chemical surface termination, which is promising for engineering heat dissipation in photothermal and thermoelectric applications of the MXenes.
270. Excitonic Spin-Coherence Lifetimes in CdSe Nanoplatelets Increase Significantly with Core/Shell Morphology
Phillip I. Martin, Shobhana Panuganti, Joshua C. Portner, Nicolas E. Watkins, Mercouri G. Kanatzidis, Dmitri V. Talapin, and Richard D. Schaller. Nano Letters 2023, 23, 4, 1467-1473
We report spin-polarized transient absorption for colloidal CdSe nanoplatelets as functions of thickness (2–6 monolayer thickness) and core/shell motif. Using electro-optical modulation of co- and cross-polarization pump–probe combinations, we sensitively observe spin-polarized transitions. Core-only nanoplatelets exhibit few-picosecond spin lifetimes that weakly increase with layer thickness. The spectral content of differenced spin-polarized signals indicate biexciton binding energies that decrease with increasing thickness and smaller values than previously reported. Shell growth of CdS with controlled thicknesses, which partially delocalize the electron from the hole, significantly increases the spin lifetime to ∼49 ps at room temperature. Implementation of ZnS shells, which do not alter delocalization but do alter surface termination, increased spin lifetimes up to ∼100 ps, bolstering the interpretation that surface termination heavily influences spin coherence, likely due to passivation of dangling bonds. Spin precession in magnetic fields both confirms long coherence lifetime at room temperature and yields the excitonic g factor.
269. Design rules for obtaining narrow luminescence from semiconductors made in solution
Hao A. Nguyen, Grant Dixon, Florence Y. Dou, Shaun Gallagher, Stephen Gibbs, Dylan Ladd, Emanuele Marino, Justin C. Ondry, James P. Shanahan, Eugenia S. Vasileiadou, Stephen Barlow, Daniel R. Gamelin, David S. Ginger, David Jonas, Mercouri G. Kanatzidis, Seth R. Marder, Daniel Morton, Christopher B. Murray, Jonathan S. Owen, Dmitri V. Talapin, Michael F. Toney, and Brandi M. Cossairt. Chemrxiv preprint.
Solution processed semiconductors are in demand for present and next-generation optoelectronic technologies ranging from displays to quantum light sources because of their scalability and ease of integration into devices with diverse form factors. One of the central requirements of semiconductors used in all these applications is a narrow photoluminescence (PL) linewidth. Narrow emission linewidths are needed to ensure both color and single-photon purity, raising the question of what design rules are needed to obtain narrow emission from semiconductors made in solution. In this review we first examine the requirements for colloidal emitters for a variety of applications including light-emitting diodes, photodetectors, lasers, and quantum information science. Next, we will delve into the sources of spectral broadening, including “homogeneous” broadening from dynamical broadening mechanisms in single-particle spectra, heterogeneous broadening from static structural differences in ensemble spectra, and spectral diffusion. Then, we compare the current state of the art in terms of emission linewidth for a variety of colloidal materials including II-VI quantum dots (QDs) and nanoplatelets, III-V QDs, alloyed QDs, metal-halide perovskites including nanocrystals and 2D structures, doped nanocrystals, and, finally, as a point of comparison, organic molecules. We end with some conclusions and connections, with an outline of promising paths forward.
268. Direct synthesis and chemical vapor deposition of 2D carbide and nitride MXenes
Di Wang, Chenkun Zhou, Alexander S. Filatov, Wooje Cho, Francisco Lagunas, Mingzhan Wang, Suriyanarayanan Vaikuntanathan, Chong Liu, Robert F. Klie, and Dmitri V. Talapin. Science 2023, 379, 6638, 1242-1247 (Cover article)
Two-dimensional transition metal carbides and nitrides (MXenes) are a large family of materials actively studied for various applications, especially in the field of energy storage. MXenes are commonly synthesized by etching the layered ternary compounds, MAX phases. We demonstrate a direct synthetic route for scalable and atom-economic synthesis of MXenes, including phases that have not been synthesized from MAX phases, by the reactions of metals and metal halides with graphite, methane, or nitrogen. The direct synthesis enables chemical vapor deposition growth of MXene carpets and complex spherulite-like morphologies that form through buckling and release of MXene carpet to expose fresh surface for further reaction. The directly synthesized MXenes showed excellent energy storage capacity for Li-ion intercalation.
267. Synthesis of Colloidal GaN and AlN Nanocrystals in Biphasic Molten Salt/Organic Solvent Mixtures under High-Pressure Ammonia
Wooje Cho, Zirui Zhou, Ruiming Lin, Justin C. Ondry, and Dmitri V. Talapin. ACS Nano 2023, 17, 2, 1315–1326
Group III nitrides are of great technological importance for electronic devices. These materials have been widely manufactured via high-temperature methods such as physical vapor transport (PVT), chemical vapor deposition (CVD), and hydride vapor phase epitaxy (HVPE). The preparation of group III nitrides by colloidal synthesis methods would provide significant advantages in the form of optical tunability via size and shape control and enable cost reductions through scalable solution-based device integration. Solution syntheses of III-nitride nanocrystals, however, have been scarce, and the quality of the synthesized products has been unsatisfactory for practical use. Here, we report that incorporating a molten salt phase in solution synthesis can provide a viable option for producing crystalline III-nitride nanomaterials. Crystalline GaN and AlN nanomaterials can be grown in a biphasic molten-salt/organic-solvent mixture under an ammonia atmosphere at moderate temperatures (less than 300 °C) and stabilized under ambient conditions by postsynthetic treatment with organic surface ligands. We suggest that microscopic reversibility of monomer attachment, which is essential for crystalline growth, can be achieved in molten salt during the nucleation and the growth of the III-nitride nanocrystals. We also show that increased ammonia pressure increases the size of the GaN nanocrystals produced. This work demonstrates that use of molten salt and high-pressure reactants significantly expands the chemical scope of solution synthesis of inorganic nanomaterials.
266. Surface passivation of intensely luminescent all-inorganic nanocrystals and their direct optical patterning
Pengwei Xiao, Zhoufan Zhang, Junjun Ge, Yalei Deng, Xufeng Chen, Jian-Rong Zhang, Zhengtao Deng, Yu Kambe, Dmitri V. Talapin, and Yuanyuan Wang. Nature Commun. 2023, 14, 49
265. Thermal Stability of Semiconductor Nanocrystal Solids: Understanding Nanocrystal Sintering and Grain Growth
Wenyong Liu, Vishwas Srivastava, J. Matthew Kurley, Chengyang Jiang, and Dmitri V. Talapin. Journal of Physical Chemistry C 2022, 126, 39, 21136–21148
264. Intrinsic glassy-metallic transport in an amorphous coordination polymer
Jiaze Xie, Simon Ewing, Jan-Niklas Boyn, Alexander S. Filatov, Baorui Cheng, Tengzhou Ma, Garrett Grocke, Norman Zhao, Ram Itani, Xiaotong Sun, Himchan Cho, Zhihengyu Chen, Karena W. Chapman, Shrayesh N. Patel, Dmitri V. Talapin, Jiwoong Park, David A. Mazziotti, and John S. Anderson. Nature 2022, 611, 479-484
Conducting organic materials, such as doped organic polymers, molecular conductors and emerging coordination polymers, underpin technologies ranging from displays to flexible electronics. Realizing high electrical conductivity in traditionally insulating organic materials necessitates tuning their electronic structure through chemical doping. Furthermore, even materials that are intrinsically conductive, such as single-component molecular conductors, require crystallinity for metallic behaviour. However, conducting polymers are often amorphous to aid durability and processability. Using molecular design to produce high conductivity in undoped amorphous materials would enable tunable and robust conductivity in many applications, but there are no intrinsically conducting organic materials that maintain high conductivity when disordered. Here we report an amorphous coordination polymer, Ni tetrathiafulvalene tetrathiolate, which displays markedly high electronic conductivity (up to 1,200 S cm−1) and intrinsic glassy-metallic behaviour. Theory shows that these properties are enabled by molecular overlap that is robust to structural perturbations. This unusual set of features results in high conductivity that is stable to humid air for weeks, pH 0–14 and temperatures up to 140 °C. These findings demonstrate that molecular design can enable metallic conductivity even in heavily disordered materials, raising fundamental questions about how metallic transport can exist without periodic structure and indicating exciting new applications for these materials.
263. Presynthetic Redox Gated Metal-to-Insulator Transition and Photothermoelectric Properties in Nickel Tetrathiafulvalene-Tetrathiolate Coordination Polymers
Jiaze Xie, Jia-Ahn Pan, Baorui Cheng, Tengzhou Ma, Alexander S. Filatov, Shrayesh N. Patel, Jiwoong Park, Dmitri V. Talapin, and John S. Anderson. J. Amer. Chem. Soc. 2022, 144, 41, 19026–19037
Photothermoelectric (PTE) materials are promising candidates for solar energy harvesting and photodetection applications, especially for near-infrared (NIR) wavelengths. Although the processability and tunability of organic materials are highly advantageous, examples of organic PTE materials are comparatively rare and their PTE performance is typically limited by poor photothermal (PT) conversion. Here, we report the use of redox-active Sn complexes of tetrathiafulvalene-tetrathiolate (TTFtt) as transmetalating agents for the synthesis of presynthetically redox tuned NiTTFtt materials. Unlike the neutral material NiTTFtt, which exhibits n-type glassy-metallic conductivity, the reduced materials Li1.2Ni0.4[NiTTFtt] and [Li(THF)1.5]1.2Ni0.4[NiTTFtt] (THF = tetrahydrofuran) display physical characteristics more consistent with p-type semiconductors. The broad spectral absorption and electrically conducting nature of these TTFtt-based materials enable highly efficient NIR-thermal conversion and good PTE performance. Furthermore, in contrast to conventional PTE composites, these NiTTFtt coordination polymers are notable as single-component PTE materials. The presynthetically tuned metal-to-insulator transition in these NiTTFtt systems directly modulates their PT and PTE properties.
262. Ligand-Free Direct Optical Lithography of Bare Colloidal Nanocrystals via Photo-Oxidation of Surface Ions with Porosity Control
Jia-Ahn Pan, Haoqi Wu, Anthony Gomez, Justin C. Ondry, Joshua Portner, Wooje Cho, Alex Hinkle, Di Wang, and Dmitri V. Talapin. ACS Nano 2022, 16, 10, 16067–16076
Microscale patterning of colloidal nanocrystal (NC) films is important for their integration in devices. Here, we introduce the direct optical patterning of all-inorganic NCs without the use of additional photosensitive ligands or additives. We determined that photoexposure of ligand-stripped, “bare” NCs in air significantly reduces their solubility in polar solvents due to photo-oxidation of surface ions. Doses as low as 20 mJ/cm2 could be used; the only obvious criterion for material selection is that the NCs need to have significant absorption at the irradiation wavelength. However, transparent NCs can still be patterned by mixing them with suitably absorbing NCs. This approach enabled the patterning of bare ZnSe, CdSe, ZnS, InP, CeO2, CdSe/CdS, and CdSe/ZnS NCs as well as mixtures of ZrO2 or HfO2 NCs with ZnSe NCs. Optical, X-ray photoelectron, and infrared spectroscopies show that solubility loss results from desorption of bound solvent due to photo-oxidation of surface ions. We also demonstrate two approaches, compatible with our patterning method, for modulating the porosity and refractive index of NC films. Block copolymer templating decreases the film density, and thus the refractive index, by introducing mesoporosity. Alternatively, hot isostatic pressing increases the packing density and refractive index of NC layers. For example, the packing fraction of a ZnS NC film can be increased from 0.51 to 0.87 upon hot isostatic pressing at 450 °C and 15 000 psi. Our findings demonstrate that direct lithography by photo-oxidation of bare NC surfaces is an accessible patterning method for facilitating the exploration of more complex NC device architectures while eliminating the influence of bulky or insulating surfactants.
261. 3D-printing nanocrystals with light (Perspective)
Jia-Ahn Pan and Dmitri V. Talapin. Science 2022, 377, 6610, 1046-1047
The ability to fabricate custom three-dimensional (3D) objects on demand has revolutionized prototyping and small-scale manufacturing processes. From low-cost filament extruders that a hobbyist can use to replace a plastic battery cover, to laser sintering machines for metal spacecraft parts, the reach of 3D printing technologies in low- and high-end markets continues to broaden. A crucial part of this progress has been the expansion of the library of materials that can be 3D-printed. Nanocrystals have many functional properties, but their integration with 3D printing has been limited, mostly relying on the use of polymer material as a scaffolding. In this issue, Liu et al. demonstrate the 3D printing of nanocrystals using a method known as two-photon lithography. The intense beam of an infrared femtosecond laser induces simultaneous absorption of two photons in a very small volume, triggering photochemical reactions at nanocrystal surfaces.
260. Diffusion-Limited Kinetics of Isovalent Cation Exchange in III-V Nanocrystals Dispersed in Molten Salt Reaction Media
Aritrajit Gupta, Justin Ondry, Min Chen, Margaret H. Hudson, Igor Coropceanu, Nivedina A. Sarma, and Dmitri V. Talapin. Nano Lett. 2022, 22, 16, 6545-6552
The goal of this work is to determine the kinetic factors that govern isovalent cation exchange in III–V colloidal quantum dots using molten salts as the solvent and cation source. We focus on the reactions of InP + GaI3→ In1–xGaxP and InAs + GaI3→ In1–xGaxAs to create technologically important ternary III–V phases. We find that the molten salt reaction medium causes the transformation of nearly spherical InP nanocrystals to tetrahedron-shaped In1–xGaxP nanocrystals. Furthermore, we determine that the activation energy for the cation exchange reaction is 0.9 eV for incorporation of Ga into InP and 1.2 eV for incorporation of Ga into InAs, both much lower than the measured values in bulk semiconductors. Next, we use powder XRD simulations to constrain our understanding of the structure of the In1–xGaxP nanocrystals. Together our results reveal several important features of molten salt-mediated cation exchange and provide guidance for future development of these materials.
259. Direct Heat-Induced Patterning of Inorganic Nanomaterials
Haoqi Wu, Yuanyuan Wang, Jaehyung Yu, Jia-Ahn Pan, Himchan Cho, Aritrajit Gupta, Igor Coropceanu, Chenkun Zhou, Jiwoong Park, and Dmitri V. Talapin. J. Amer. Chem. Soc. 2022, 144, 23, 10495–10506
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258. Self-Assembly of Nanocrystals into Strongly Electronically Coupled All-Inorganic Supercrystals
Igor Coropceanu, Eric M. Janke, Joshua Portner, Danny Haubold, Trung Dac Nguyen, Avishek Das, Christian P. N. Tanner, James K. Utterback, Samuel W. Teitelbaum, Margaret H. Hudson, Nivedina A. Sarma, Alex M. Hinkle, Christopher J. Tassone, Alexander Eychmüller, David T. Limmer, Monica Olvera de la Cruz, Naomi S. Ginsberg, and Dmitri V. Talapin. Science 2022, 375, 6587, 1422–1426
UChicago News: Scientists shave ‘hairs’ off nanocrystals to improve their electronic properties
257. Synthesis of In1–xGaxP Quantum Dots in Lewis Basic Molten Salts: The Effects of Surface Chemistry, Reaction Conditions, and Molten Salt Composition
Margaret H. Hudson, Aritrajit Gupta, Vishwas Srivastava, Eric M. Janke, and Dmitri V. Talapin. J. Phys. Chem. C. 2022, 126, 3, 1564–1580
Inorganic molten salts are emerging as versatile solvents for high-temperature processing of colloidal nanocrystals. Molten alkali bromide eutectics can serve as a convenient solvent for the transformation of InP quantum dots (QDs) to In1–xGaxP QDs, with simultaneous tuning of the composition and band gap. Here, we explore various aspects of this molten salt indium-to-gallium cation exchange in-depth, including the nanocrystal surface chemistry, reaction conditions, and salt composition, to obtain a more detailed understanding and finer control over the transformation. InP QDs capped with (DDA)2S, (NH4)2S, Li2Se, GaCl3, or InCl3 can be homogenously dispersed in a molten bromide salt mixture. We demonstrate that chalcogenide capping ligands improve the high temperature stability of InP QDs through the formation of a chalcogen-rich layer which prevents InP decomposition. For each surface chemistry studied, the indium-to-gallium cation exchange proceeds similarly, yielding colloidal In1–xGaxP QDs with an increased band gap and decreased lattice constant. By carefully engineering the reaction conditions and protecting the nanoparticles from oxidative exposure, we achieve a narrow emission linewidth of 41 nm full width at half maximum from the alloyed In1–xGaxP colloidal QDs. These insights provide the design space for colloidal synthesis in molten inorganic salts and introduce synthetic methods for In1–xGaxP QDs with tunable composition and properties. Our work demonstrates the development of nontoxic QD emitters with optimized stability, color purity, and luminescence quantum efficiency.
256. Active learning of polarizable nanoparticle phase diagrams for the guided design of triggerable self-assembling superlattices
Siva Dasetty, Igor Coropceanu, Joshua Portner, Jiyuan Lia, Juan J. de Pablo, Dmitri Talapin, and Andrew L. Ferguson. Mol. Syst. Des. Eng. 2022, 7, 350-363
Polarizable nanoparticles are of interest in materials science because of their rich and complex phase behavior that can be used to engineer nanostructured materials with long-range crystalline order. To understand and rationally navigate the design space of polarizable nanoparticles for self-assembling highly ordered superlattices, we developed a coarse-grained computational model to describe the nanoparticle–nanoparticle interactions in implicit solvent and employ the computationally efficient image method to model many-body polarization interactions. We conducted high-throughput virtual screening over a five-dimensional particle design space spanned by temperature, particle size, particle charge, particle dielectric, and solvent dielectric using enhanced sampling molecular dynamics calculations within an active learning framework to efficiently map out the regions of thermodynamic stability of the self-assembled aggregates. We validate our predictions in comparisons against small angle X-ray scattering measurements of gold nanoparticles surface functionalized with metal chalcogenide complex ligands. Finally, we use our validated phase maps to computationally design switchable nanostructured materials capable of triggered assembly and disassembly as a function of temperature and solvent dielectric with potential applications as sensors, smart windows, optoelectronic devices, and in medical diagnostics.
255. Magnetoresistance of high mobility HgTe quantum dot films with controlled charging
Menglu Chen, Xinzheng Lan, Margaret H. Hudson, Guohua Shen, Peter B. Littlewood, Dmitri V. Talapin and Philippe Guyot-Sionnest. J. Mater. Chem. C 2022, 10, 13771–13777
The magnetoresistance of HgTe quantum dot films, exhibiting a well-defined 1Se state charging and a relatively high mobility (1–10 cm2 V−1 s−1), is measured as a function of temperature down to 10 K and controlled occupation of the first electronic state. There is a positive-quadratic magnetoresistance which can be several 100% at low temperature and scales like x(1 − x) where x is the filling fraction of the lowest quantum dot state in the conduction band, 1Se. This positive magnetoresistance is orders of magnitude larger than the effect estimated from mobile carriers and it is attributed to the increased confinement induced by the magnetic field. There is also a negative magnetoresistance of 1–20% from 300 K to 10 K which is rather independent of the fractional occupation, and which follows a negative exponential dependence with the magnetic field. It can be empirically fit with an effective g-factor of ∼55 and it is tentatively attributed to the reduction of barrier heights by the Zeeman splitting of the 1Se state.
254. Roll-To-Roll Friendly Solution-Processing of Ultrathin, Sintered CdTe Nanocrystal Photovoltaics
J. Matthew Kurley,⊥ Jia-Ahn Pan,⊥ Yuanyuan Wang, Hao Zhang, Jake C. Russell, Gregory F. Pach,
Bobby To, Joseph M. Luther, and Dmitri V. Talapin. ACS Appl. Mater. Interfaces. 2021, 13, 37, 44165-44173
Roll-to-roll (R2R) device fabrication using solution-processed materials is a cheap and versatile approach that has attracted widespread interest over the past 2 decades. Here, we systematically introduce and investigate R2R-friendly modifications in the fabrication of ultrathin, sintered CdTe nanocrystal (NC) solar cells. These include (1) scalable deposition techniques such as spray-coating and doctor-blading, (2) a bath-free, controllable sintering of CdTe NCs by quantitative addition of a sintering agent, and (3) radiative heating with an infrared lamp. The impact of each modification on the CdTe nanostructure and solar cell performance was first independently studied and compared to the standard, non-R2R-friendly procedure involving spin-coating the NCs, soaking in a CdCl2 bath, and annealing on a hot plate. The R2R-friendly techniques were then combined into a single, integrated process, yielding devices that reach 10.4% power conversion efficiency with a Voc, Jsc, and FF of 697 mV, 22.2 mA/cm2, and 67%, respectively, after current/light soaking. These advances reduce the barrier for large-scale manufacturing of solution-processed, ultralow-cost solar cells on flexible or curved substrates.
253. Direct Optical Lithography of CsPbX3 Nanocrystals via Photoinduced Ligand Cleavage with Postpatterning Chemical Modification and Electronic Coupling
Jia-Ahn Pan, Justin C. Ondry, Dmitri V. Talapin. Nano Lett. 2021, 21, 18, 7609-7616
Microscale patterning of solution-processed nanomaterials is important for integration in functional devices. Colloidal lead halide perovskite (LHP) nanocrystals (NCs) can be particularly challenging to pattern due to their incompatibility with polar solvents and lability of surface ligands. Here, we introduce a direct photopatterning approach for LHP NCs through the binding and subsequent cleavage of a photosensitive oxime sulfonate ester (−C═N–OSOO−). The photosensitizer binds to the NCs through its sulfonate group and is cleaved at the N–O bond during photoirradiation with 405 nm light. This bond cleavage decreases the solubility of the NCs, which allows patterns to emerge upon development with toluene. Postpatterning ligand exchange results in photoluminescence quantum yields of up to 79%, while anion exchange provides tunability in the emission wavelength. The patterned NC films show photoconductive behavior, demonstrating that good electrical contact between the NCs can be established.
252. Semiconductor quantum dots: Technological progress and future challenges
F. Pelayo García de Arquer, Dmitri V. Talapin, Victor I. Klimov, Yasuhiko Arakawa, Manfred Bayer, Edward H. Sargent. Science 2021, 373, 640, eaaz8541.
In quantum-confined semiconductor nanostructures, electrons exhibit distinctive behavior compared with that in bulk solids. This enables the design of materials with tunable chemical, physical, electrical, and optical properties. Zero-dimensional semiconductor quantum dots (QDs) offer strong light absorption and bright narrowband emission across the visible and infrared wavelengths and have been engineered to exhibit optical gain and lasing. These properties are of interest for imaging, solar energy harvesting, displays, and communications. Here, we offer an overview of advances in the synthesis and understanding of QD nanomaterials, with a focus on colloidal QDs, and discuss their prospects in technologies such as displays and lighting, lasers, sensing, electronics, solar energy conversion, photocatalysis, and quantum information.
251. Advanced Materials for Energy-Water Systems: The Central Role of Water/Solid Interfaces in Adsorption, Reactivity, and Transport
Edward Barry, Raelyn Burns, Wei Chen, Guilhem X De Hoe, Joan Manuel Montes De Oca, Juan J de Pablo, James Dombrowski, Jeffrey W Elam, Alanna M Felts, Giulia Galli, John Hack, Qiming He, Xiang He, Eli Hoenig, Aysenur Iscen, Benjamin Kash, Harold H Kung, Nicholas HC Lewis, Chong Liu, Xinyou Ma, Anil Mane, Alex BF Martinson, Karen L Mulfort, Julia Murphy, Kristian Mølhave, Paul Nealey, Yijun Qiao, Vepa Rozyyev, George C Schatz, Steven J Sibener, Dmitri Talapin, David M Tiede, Matthew V Tirrell, Andrei Tokmakoff, Gregory A Voth, Zhongyang Wang, Zifan Ye, Murat Yesibolati, Nestor J Zaluzec, Seth B Darling. Chem. Rev. 2021, 121, 15, 9450–9501
The structure, chemistry, and charge of interfaces between materials and aqueous fluids play a central role in determining properties and performance of numerous water systems. Sensors, membranes, sorbents, and heterogeneous catalysts almost uniformly rely on specific interactions between their surfaces and components dissolved or suspended in the water—and often the water molecules themselves—to detect and mitigate contaminants. Deleterious processes in these systems such as fouling, scaling (inorganic deposits), and corrosion are also governed by interfacial phenomena. Despite the importance of these interfaces, much remains to be learned about their multiscale interactions. Developing a deeper understanding of the molecular- and mesoscale phenomena at water/solid interfaces will be essential to driving innovation to address grand challenges in supplying sufficient fit-for-purpose water in the future. In this Review, we examine the current state of knowledge surrounding adsorption, reactivity, and transport in several key classes of water/solid interfaces, drawing on a synergistic combination of theory, simulation, and experiments, and provide an outlook for prioritizing strategic research directions.
250. Observation of biexciton emission from single semiconductor nanoplatelets
Quasi-two-dimensional semiconductor nanoplatelets (NPLs) are intriguing systems for studying the influence of Auger recombination processes on the multiexciton emission efficiencies in the weak in-plane confinement regime. We investigate CdSe/CdS core/shell NPLs using cryogenic temperature single particle spectroscopy and observe bright biexciton emission at high excitation powers. The average binding energy of the biexcitons is determined to be 16.5 meV. The observed switching between the biexciton and trion states indicates charging-decharging dynamics of the NPLs mediated by the Auger ionization process. These findings are highly relevant for harvesting efficient biexciton emission for energy, lighting, and quantum applications.
249. Nanoscale Disorder Generates Subdiffusive Heat Transport in Self-Assembled Nanocrystal Films
James K Utterback, Aditya Sood, Igor Coropceanu, Burak Guzelturk, Dmitri V Talapin, Aaron M Lindenberg, Naomi S Ginsberg. Nano Lett. 2021, 21, 8, 3540–3547.
Investigating the impact of nanoscale heterogeneity on heat transport requires a spatiotemporal probe of temperature on the length and time scales intrinsic to heat navigating nanoscale defects. Here, we use stroboscopic optical scattering microscopy to visualize nanoscale heat transport in disordered films of gold nanocrystals. We find that heat transport appears subdiffusive at the nanoscale. Finite element simulations show that tortuosity of the heat flow underlies the subdiffusive transport, owing to a distribution of nonconductive voids. Thus, while heat travels diffusively through contiguous regions of the film, the tortuosity causes heat to navigate circuitous pathways that make the observed mean-squared expansion of an initially localized temperature distribution appear subdiffusive on length scales comparable to the voids. Our approach should be broadly applicable to uncover the impact of both designed and unintended heterogeneities in a wide range of materials and devices that can affect more commonly used spatially averaged thermal transport measurements.
248. Room temperature single-photon superfluorescence from a single epitaxial cuboid nano-heterostructure
John P Philbin, Joseph Kelly, Lintao Peng, Igor Coropceanu, Abhijit Hazarika, Dmitri V Talapin, Eran Rabani, Xuedan Ma, Prineha Narang. arXiv. 2021.
Single-photon superradiance can emerge when a collection of identical emitters are spatially separated by distances much less than the wavelength of the light they emit, and is characterized by the formation of a superradiant state that spontaneously emits light with a rate that scales linearly with the number of emitters. This collective phenomena has only been demonstrated in a few nanomaterial systems, all requiring temperatures below 10K. Here, we rationally design a single colloidal nanomaterial that hosts multiple (nearly) identical emitters that are impervious to the fluctuations which typically inhibit room temperature superradiance in other systems such as molecular aggregates. Specifically, by combining molecular dynamics, atomistic electronic structure calculations, and model Hamiltonian methods, we show that the faces of a heterostructure nanocuboid mimic individual quasi-2D nanoplatelets and can serve as the robust emitters required to realize superradiant phenomena at room temperature. Leveraging layer-by-layer colloidal growth techniques to synthesize a nanocuboid, we demonstrate single-photon superfluorescence via single-particle time-resolved photoluminescence measurements at room temperature. This robust observation of both superradiant and subradiant states in single nanocuboids opens the door to ultrafast single-photon emitters and provides an avenue to entangled multi-photon states via superradiant cascades.
247. Dynamic lattice distortions driven by surface trapping in semiconductor nanocrystals
Burak Guzelturk, Benjamin L Cotts, Dipti Jasrasaria, John P Philbin, David A Hanifi, Brent A Koscher, Arunima D Balan, Ethan Curling, Marc Zajac, Suji Park, Nuri Yazdani, Clara Nyby, Vladislav Kamysbayev, Stefan Fischer, Zach Nett, Xiaozhe Shen, Michael E Kozina, Ming-Fu Lin, Alexander H Reid, Stephen P Weathersby, Richard D Schaller, Vanessa Wood, Xijie Wang, Jennifer A Dionne, Dmitri V Talapin, A Paul Alivisatos, Alberto Salleo, Eran Rabani, Aaron M Lindenberg. Nat. Com. 2021, 12, 1.
Nonradiative processes limit optoelectronic functionality of nanocrystals and curb their device performance. Nevertheless, the dynamic structural origins of nonradiative relaxations in such materials are not understood. Here, femtosecond electron diffraction measurements corroborated by atomistic simulations uncover transient lattice deformations accompanying radiationless electronic processes in colloidal semiconductor nanocrystals. Investigation of the excitation energy dependence in a core/shell system shows that hot carriers created by a photon energy considerably larger than the bandgap induce structural distortions at nanocrystal surfaces on few picosecond timescales associated with the localization of trapped holes. On the other hand, carriers created by a photon energy close to the bandgap of the core in the same system result in transient lattice heating that occurs on a much longer 200 picosecond timescale, dominated by an Auger heating mechanism. Elucidation of the structural deformations associated with the surface trapping of hot holes provides atomic-scale insights into the mechanisms deteriorating optoelectronic performance and a pathway towards minimizing these losses in nanocrystal devices.
246. Direct Optical Lithography of Colloidal Metal Oxide Nanomaterials for Diffractive Optical Elements with 2π Phase Control
Jia-Ahn Pan, Zichao Rong, Yuanyuan Wang, Himchan Cho, Igor Coropceanu, Haoqi Wu, and Dmitri V. Talapin. J. Am. Chem. Soc. 2021, 143, 5, 2372–2383.
Spatially patterned dielectric materials are ubiquitous in electronic, photonic, and optoelectronic devices. These patterns are typically made by subtractive or additive approaches utilizing vapor-phase reagents. On the other hand, recent advances in solution-phase synthesis of oxide nanomaterials have unlocked a materials library with greater compositional, microstructural, and interfacial tunability. However, methods to pattern and integrate these nanomaterials in real-world devices are less established. In this work, we directly optically pattern oxide nanoparticles (NPs) by mixing them with photosensitive diazo-2-naphthol-4-sulfonic acid and irradiating with widely available 405 nm light. We demonstrate the direct optical lithography of ZrO2, TiO2, HfO2, and ITO NPs and investigate the chemical and physical changes responsible for this photoinduced decrease in solubility. For example, micron-thick layers of amorphous ZrO2 NPs were patterned with micron resolution and shown to allow 2pi phase control of visible light. We also show multilayer patterning and use it to fabricate features with different thicknesses and distinct structural colors. Upon annealing at 400 C, the deposited structures have excellent optical transparency across a wide wavelength range (0.3 – 10 um), a high refractive index (n = 1.84 at 633 nm) and are optically smooth. We then fabricate diffractive optical elements, such as binary phase diffraction gratings, that show efficient diffractive behavior and good thermal stability. Different oxide NPs can also be mixed prior to patterning, providing a high level of material tunability. This work demonstrates a general patterning approach that harnesses the processability and diversity of colloidal oxide nanomaterials for use in photonic applications.
245. Stoichiometry of the Core Determines the Electronic Structure of Core–Shell III–V/II–VI Nanoparticles
Mariami Rusishvili, Stefan Wippermann, Dmitri V. Talapin, and Giulia Galli. Chem. Mater. 2020, 32, 9798-9804.
244. Functional materials and devices by self-assembly
Dmitri V. Talapin, Michael Engel, and Paul V. Braun. MRS Bull. 2020, 45, 799.
243. Direct Optical Patterning of Quantum Dot Light‐Emitting Diodes via In Situ Ligand Exchange
Himchan Cho, Jia‐Ahn Pan, Haoqi Wu, Xinzheng Lan, Igor Coropceanu, Yuanyuan Wang, Wooje Cho, Ethan A. Hill, John S. Anderson, and Dmitri V. Talapin. Adv. Mater. 2020, 32, 2003805.
242. Area and thickness dependence of Auger recombination in nanoplatelets
John P. Philbin, Alexandra Brumberg, Benjamin T. Diroll, Wooje Cho, Dmitri V. Talapin, Richard D. Schaller, and Eran Rabani. J. Chem. Phys. 2020, 153, 054104.
241. Covalent surface modifications and superconductivity of two-dimensional metal carbide MXenes
Vladislav Kamysbayev, Alexander S. Filatov, Huicheng Hu, Xue Rui, Francisco Lagunas, Di Wang, Robert F. Klie, and Dmitri V. Talapin. Science 2020, 369, 979.
UChicago News: UChicago chemists invent way to customize compounds just a few atoms thick
240. sasPDF: pair distribution function analysis of nanoparticle assemblies from small-angle scattering data
Chia-Hao Liu, Eric M. Janke, Ruipen Li, Pavol Juhás, Oleg Gang, Dmitri V. Talapin, and Simon J. L. Billinge. J. Appl. Cryst. 2020, 53, 699.
239. Bright trion emission from semiconductor nanoplatelets
Lintao Peng, Matthew Otten, Abhijit Hazarika, Igor Coropceanu, Moritz Cygorek, Gary P. Wiederrecht, Pawel Hawrylak, Dmitri V. Talapin, and Xuedan Ma. Phys. Rev. Materials 2020, 4, 056006.
238. Heat-driven acoustic phonons in lamellar nanoplatelet assemblies
Benjamin T. Diroll, Vladislav Kamysbayev, Igor Coropceanu, Dmitri V. Talapin, and Richard D. Schaller. Nanoscale 2020, 12, 9661.
237. Nonequilibrium Thermodynamics of Colloidal Gold Nanocrystals Monitored by Ultrafast Electron Diffraction and Optical Scattering Microscopy
Burak Guzelturk, James K. Utterback, Igor Coropceanu, Vladislav Kamysbayev, Eric M. Janke, Marc Zajac, Nuri Yazdani, Benjamin L. Cotts, Suji Park, Aditya Sood, Ming-Fu Lin, Alexander H. Reid, Michael E. Kozina, Xiaozhe Shen, Stephen P. Weathersby, Vanessa Wood, Alberto Salleo, Xijie Wang, Dmitri V. Talapin, Naomi S. Ginsberg, and Aaron M. Lindenberg. ACS Nano 2020, 14, 4792.
236. Quantized Reaction Pathways for Solution Synthesis of Colloidal ZnSe Nanostructures: A Connection between Clusters, Nanowires, and Two-Dimensional Nanoplatelets
P. D. Cunningham, Igor Coropceanu, K. Mulloy, W. Cho, D. V. Talapin. ACS Nano 2020, 14, 3847.
235. Quantum dot solids showing state-resolved band-like transport
X. Lan, M. Chen, M. H. Hudson, V. Kamysbayev, Y. Wang, P. Guyot-Sionnest, and D. V. Talapin. Nature Mater. 2020, 19, 323.
234. Hot-Carrier Relaxation in CdSe/CdS Core/Shell Nanoplatelets
M. Pelton, Y, Wang, I. Fedin, D. V. Talapin, S. K. O’Leary. J. Phys. Chem. C 2020, 124, 1020.
233. Titanium Nitride Modified Photoluminescence from Single Semiconductor Nanoplatelets
L. Peng, X. Wang, I. Coropceanu, A. B. Martinson, H. Wang, D. V. Talapin, and X. Ma. Adv. Funct. Mater. 2020, 30, 1904179.
232. Direct Wavelength-Selective Optical and Electron-Beam Lithography of Functional Inorganic Nanomaterials
Y. Wang, J.-A. Pan, H. Wu, and D. V. Talapin. ACS Nano 2019, 13, 13917.
231. Colloidal Gelation in Liquid Metals Enables Functional Nanocomposites of 2D Metal Carbides (MXenes) and Lightweight Metals
V. Kamysbayev, N. M. James, A. S. Filatov, V. Srivastava, B. Anasori, H. M. Jaeger, Y. Gogotsi, and D. V. Talapin. ACS Nano 2019, 13, 12415.
230. Polarized near-infrared intersubband absorptions in CdSe colloidal quantum wells
B. T. Diroll, M. Chen, I. Coropceanu, K. R. Williams, D. V. Talapin, P. Guyot-Sionnest, and R. D. Schaller. Nat. Commun. 2019, 10, 4511.
229. High Carrier Mobility in HgTe Quantum Dot Solids Improves Mid-IR Photodetectors
M. Chen, X. Lan, X. Tang, Y. Wang, M. H. Hudson, D. V. Talapin, and P. Guyot-Sionnest. ACS Photonics 2019, 6, 2358.
228. Colloidal Atomic Layer Deposition with Stationary Reactant Phases Enables Precise Synthesis of “Digital” II-VI Nano-heterostructures with Exquisite Control of Confinement and Strain
A. Hazarika, I. Fedin, L. Hong, J. Guo, V. Srivastava, W. Cho, I. Coropceanu, J. C. Portner, B. T. Diroll, J. P. Philbin, E. Rabani, R. F. Klie, and D. V. Talapin. J. Am. Chem. Soc. 2019, 141, 13487.
227. Uniaxial transition dipole moments in semiconductor quantum rings caused by broken rotational symmetry
N. F. Hartmann, M. Otten, I. Fedin, D. V. Talapin, M. Cygorek, P. Hawrylak, M. Korkusinski, S. Gray, A. Hartschuh, and X. Ma. Nat. Commun. 2019, 10, 3253.
226. Binary Assembly of PbS and Au Nanocrystals: Patchy PbS Surface Ligand Coverage Stabilizes the CuAu Superlattice
M. Boles and D. V. Talapin. ACS Nano 2019, 13, 5375.
225. Nanocrystals in Molten Salts and Ionic Liquids: Experimental Observation of Ionic Correlations Extending beyond the Debye Length
V. Kamysbayev, V. Srivastava, N. B. Ludwig, O. J. Borkiewicz, H. Zhang, J. Ilavsky, B. Lee, K. W. Chapman, S. Vaikuntanathan, D. V. Talapin. ACS Nano 2019, 13, 5760.
224. Systematic Mapping of Binary Nanocrystal Superlattices: The Role of Topology in Phase Selection
I. Coropceanu, M. A. Boles, D. V. Talapin. J. Am. Chem. Soc. 2019, 141, 5728.
223. Describing screening in dense ionic liquids with a charge-frustrated Ising model
N. B. Ludwig, K. Dasbiswas, D. V. Talapin, S. Vaikuntanathan. J. Chem. Phys. 2018, 149, 164505.
222. Origin of Broad Emission Spectra in InP Quantum Dots: Contributions from Structural and Electronic Disorder
E. M. Janke, N. E. Williams, C. She, D. Zherebetskyy, M. Hudson, L. Wang, D. J. Gosztola, R. D. Schaller, B. Lee, C. Sun, G. S. Engel, D. V. Talapin. J. Am. Chem. Soc. 2018, 140, 15791.
221. Direct Synthesis of Six-Monolayer (1.9 nm) Thick Zinc-Blende CdSe Nanoplatelets Emitting at 585 nm
W. Cho, S. Kim, I. Coropceanu, V. Srivastava, B. T. Diroll, A. Hazarika, I. Fedin, R. D. Schaller, G. Galli, D. V. Talapin. Chem. Mater. 2018, 30, 6957.
220. Semiconductor Nanoplatelet Excimers
B. T. Diroll, W. Cho, I. Coropceanu, S. Harvey, A. Brumberg, N. Holtgrewe, S. A. Crooker, M. R. Wasielewski, V. B. Prakapenka, D. V. Talapin, R. D. Schaller. Nano Lett. 2018, 18, 6948.
219. Colloidal Chemistry in Molten Salts: Synthesis of Luminescent In1–xGaxP and In1–xGaxAs Quantum Dots
V. Srivastava, V. Kamysbayev, L. Hong, E. Dunietz, R. F. Klie, D. V. Talapin. J. Am. Chem. Soc. 2018, 140, 12144.
218. Conduction Band Fine Structure in Colloidal HgTe Quantum Dots
M. H. Hudson, M. Chen, V. Kamysbayev, E. M. Janke, X. Lan, G. Allan, C. Delerue, B. Lee, P. Guyot-Sionnest, D. V. Talapin. ACS Nano 2018, 12, 9397.
217. Anisotropic photoluminescence from isotropic optical transition dipoles in semiconductor nanoplatelets
X. Ma, B. T. Diroll, W. Cho, I. Fedin, R. D. Schaller, D. V. Talapin, and G. P. Wiederrecht. Nano Lett. 2018, 18, 4647.
216. Surface chemistry and buried interfaces in all-inorganic nanocrystalline solids
E. Scalise, V. Srivastava, E. M. Janke, D. Talapin, G. Galli, and S. Wippermann. Nature Nanotech. 2018, 33, 841.
215. Monodisperse InAs Quantum Dots from Aminoarsine Precursors: Understanding the Role of Reducing Agent
V. Srivastava, E. Dunietz, V. Kamysbayev, J. S. Anderson, and D. V. Talapin. Chem. Mater. 2018, 30, 3623.
214. Elevated Temperature Photophysical Properties and Morphological Stability of CdSe and CdSe/CdS Nanoplatelets
C. E. Rowland, I. Fedin, B. T. Diroll, Y. Liu, D. V. Talapin, and R. D. Schaller. J. Phys. Chem. Lett. 2018, 9, 286.
213. Nonmonotonic Dependence of Auger Recombination Rate on Shell Thickness for CdSe/CdS Core/Shell Nanoplatelets
M. Pelton, J. J. Andrews, I. Fedin, D. V. Talapin, H. Lengd S. K. O’Leary. Nano Lett. 2017, 17, 6900.
212. Size-Dependent Biexciton Quantum Yields and Carrier Dynamics of Quasi-Two-Dimensional Core/Shell Nanoplatelets
X. Ma, B. T. Diroll, W. Cho, I. Fedin, R. D. Schaller, D. V. Talapin, S. K. Gray, G. P. Wiederrecht, and D. J. Gosztola. ACS Nano 2017, 11, 9119.
211. Direct optical lithography of functional inorganic nanomaterials
Y. Wang, I. Fedin, H. Zhang, and D. V. Talapin. Science 2017, 357, 385.
Perspective: M. Striccoli. Photolithography based on nanocrystals. Science 2017, 357, 353.
210. A room temperature continuous-wave nanolaser using colloidal quantum wells
Z. Yang, M. Pelton, I. Fedin, D. V. Talapin, and E. Waks. Nat. Commun. 2017, 8, 143.
209. Soluble Lead and Bismuth Chalcogenidometallates: Versatile Solders for Thermoelectric Materials
H. Zhang, J. S. Son, D. S. Dolzhnikov, A. S. Filatov, A. Hazarika, Y. Wang, M. H. Hudson, C.-J. Sun, S. Chattopadhyay, and D. V. Talapin. Chem. Mater. 2017, 29, 6396.
208. Orbitals, Occupation Numbers, and Band Structure of Short One-Dimensional Cadmium Telluride Polymers
A. J. S. Valentine, D. V. Talapin, and D. A. Mazziotti. J. Phys. Chem. A 2017, 121, 3142.
207. Stable colloids in molten inorganic salts
H. Zhang, K. Dasbiswas, N. B. Ludwig, G. Han, B. Lee, S. Vaikuntanathan, and D. V. Talapin. Nature 2017, 542, 328.
206. Understanding and curing structural defects in colloidal GaAs nanocrystals
V. Srivastava, W. Liu, E. M. Janke, V. Kamysbayev, A. S. Filatov, C. Sun, B. Lee, Tijana Rajh, R. D. Schaller, and D. V. Talapin. Nano Lett. 2017, 17, 2094.
205. Violet-to-Blue Gain and Lasing from Colloidal CdS Nanoplatelets: Low-Threshold Stimulated Emission Despite Low Photoluminescence Quantum Yield
B. T. Diroll, D. V. Talapin, and R. D. Schaller. ACS Photonics 2017, 4, 576.
204. New forms of CdSe: molecular wires, gels, and ordered mesoporous assemblies
M. H. Hudson, D. S. Dolzhnikov, A. S. Filatov, E. M. Janke, J. Jang, B. Lee, C. Sun, and D. V. Talapin. J. Am. Chem. Soc. 2017, 139, 3368.
203. Tandem Solar Cells from Solution-Processed CdTe and PbS Quantum Dots Using a ZnTe–ZnO Tunnel Junction
R. W. Crisp, G. F. Pach, J. M. Kurley, R. M. France, M. O. Reese, S. U. Nanayakkara, B. A. MacLeod, D. V. Talapin, M. C. Beard, and J. M. Luther. Nano Lett. 2017, 17, 1020.
202. Transparent Ohmic Contacts for Solution-Processed, Ultrathin CdTe Solar Cells
J. M. Kurley, M. G. Panthani, R. W. Crisp, S. U. Nanayakkara, G. F. Pach, M. O. Reese, M. H. Hudson, D. S. Dolzhnikov, V. Tanygin, J. M. Luther, and D. V. Talapin. ACS Energy Lett. 2017, 2, 270.