Joshua E. Goldberger

Bio: Joshua E. Goldberger is an academic researcher from Ohio State University. The author has contributed to research in topics: Germanane & Graphane. The author has an hindex of 38, co-authored 108 publications receiving 15073 citations. Previous affiliations of Joshua E. Goldberger include National Center for Electron Microscopy & Lawrence Berkeley National Laboratory.

Self-assembling molecules that accumulate in acidic tumor microenvironments

Abstract: Disclosed are compositions that contain a plurality of biocompatible self-assembling molecules that transform from isolated molecules or spherical micelles in the circulation into cylindrical nanofibers in the acidic extracellular environment of tumors which can be used to achieve a higher relative concentration of imaging, drug delivery, or radiotherapeutic agents at the tumor site compared to non-tumor tissues. This transition is rapid and reversible, indicating the system is in thermodynamic equilibrium.

Dynamics of Two Distinct Exciton Populations in Methyl-functionalized Germanane.

Abstract: Methyl-substituted Germanane is an emerging material that has been proposed for novel applications in optoelectronics, photoelectrocatalysis, and biosensors. It is a two-dimensional semiconductor with a strong above-gap fluorescence associated with water intercalation. Here, we use time-resolved photoluminescence spectroscopy to understand the mechanism causing this fluorescence. We show that it originates from two distinct exciton populations. Both populations recombine exponentially, accompanied by the thermally activated transfer of exciton population from the shorter- to the longer-lived type. The two exciton populations involve different electronic levels and couple to different phonons. The longer-lived type of exciton migrates within the disordered energy landscape of localized recombination centers. These outcomes shed light on the fundamental optical and electronic properties of functionalized germanane, enabling the groundwork for future applications in optoelectronics, light-harvesting, and sensing.

Method of non-catalytic formation and growth of nanowires

Abstract: A method for the non-catalytic growth of nanowires is provided. The method includes a reaction chamber with the chamber having an inlet end, an exit end and capable of being heated to an elevated temperature. A carrier gas with a flow rate is allowed to enter the reaction chamber through the inlet end and exit the chamber through the exit end. Upon passing through the chamber the carrier gas comes into contact with a precursor which is heated within the reaction chamber. A collection substrate placed downstream from the precursor allows for the formation and growth of nanowires thereon without the use of a catalyst. A second embodiment of the present invention is comprised of a reaction chamber, a carrier gas, a precursor target, a laser beam and a collection substrate. The carrier gas with a flow rate and a gas pressure is allowed to enter the reaction chamber through an inlet end and exit the reaction chamber through the exit end. The laser beam is focused on the precursor target which affords for the evaporation of the precursor material and subsequent formation and growth of nanowires on the collection substrate.

Atomic-Scale Derivatives of Solid-State Materials

Abstract: There has been an expanding library of materials in which the framework connectivity of prevalent solid-state crystal structure types is terminated with ligands along specific axes to produce robust, crystalline, single- and few-atom/polyhedral thick fragments. The abrupt termination of the ionic/covalent inorganic framework along a particular direction, gives these materials fundamentally different electronic, optical, thermal, and magnetic properties, which can be manipulated via the design of the organic component. These new materials often exhibit advantageous electronic and optoelectronic behavior, making them viable platforms for applications ranging from light emitting phosphors, to thin film field effect transistors, to photovoltaics. This Perspective highlights our current understanding and future opportunities in the synthesis, properties, and applications of these atomic-scale derivatives of solid-state materials.

Electronics and optoelectronics of two-dimensional transition metal dichalcogenides.

Abstract: Single-layer metal dichalcogenides are two-dimensional semiconductors that present strong potential for electronic and sensing applications complementary to that of graphene.

Van der Waals heterostructures

Abstract: Fabrication techniques developed for graphene research allow the disassembly of many layered crystals (so-called van der Waals materials) into individual atomic planes and their reassembly into designer heterostructures, which reveal new properties and phenomena. Andre Geim and Irina Grigorieva offer a forward-looking review of the potential of layering two-dimensional materials into novel heterostructures held together by weak van der Waals interactions. Dozens of these one-atom- or one-molecule-thick crystals are known. Graphene has already been well studied but others, such as monolayers of hexagonal boron nitride, MoS2, WSe2, graphane, fluorographene, mica and silicene are attracting increasing interest. There are many other monolayers yet to be examined of course, and the possibility of combining graphene with other crystals adds even further options, offering exciting new opportunities for scientific exploration and technological innovation. Research on graphene and other two-dimensional atomic crystals is intense and is likely to remain one of the leading topics in condensed matter physics and materials science for many years. Looking beyond this field, isolated atomic planes can also be reassembled into designer heterostructures made layer by layer in a precisely chosen sequence. The first, already remarkably complex, such heterostructures (often referred to as ‘van der Waals’) have recently been fabricated and investigated, revealing unusual properties and new phenomena. Here we review this emerging research area and identify possible future directions. With steady improvement in fabrication techniques and using graphene’s springboard, van der Waals heterostructures should develop into a large field of their own.

Chemistry and properties of nanocrystals of different shapes.

Abstract: The interest in nanoscale materials stems from the fact that new properties are acquired at this length scale and, equally important, that these properties * To whom correspondence should be addressed. Phone, 404-8940292; fax, 404-894-0294; e-mail, mostafa.el-sayed@ chemistry.gatech.edu. † Case Western Reserve UniversitysMillis 2258. ‡ Phone, 216-368-5918; fax, 216-368-3006; e-mail, burda@case.edu. § Georgia Institute of Technology. 1025 Chem. Rev. 2005, 105, 1025−1102

Nanowire dye-sensitized solar cells

Abstract: Excitonic solar cells1—including organic, hybrid organic–inorganic and dye-sensitized cells (DSCs)—are promising devices for inexpensive, large-scale solar energy conversion. The DSC is currently the most efficient2 and stable3 excitonic photocell. Central to this device is a thick nanoparticle film that provides a large surface area for the adsorption of light-harvesting molecules. However, nanoparticle DSCs rely on trap-limited diffusion for electron transport, a slow mechanism that can limit device efficiency, especially at longer wavelengths. Here we introduce a version of the dye-sensitized cell in which the traditional nanoparticle film is replaced by a dense array of oriented, crystalline ZnO nanowires. The nanowire anode is synthesized by mild aqueous chemistry and features a surface area up to one-fifth as large as a nanoparticle cell. The direct electrical pathways provided by the nanowires ensure the rapid collection of carriers generated throughout the device, and a full Sun efficiency of 1.5% is demonstrated, limited primarily by the surface area of the nanowire array.

Progress, Challenges, and Opportunities in Two-Dimensional Materials Beyond Graphene

Abstract: Graphene’s success has shown that it is possible to create stable, single and few-atom-thick layers of van der Waals materials, and also that these materials can exhibit fascinating and technologically useful properties. Here we review the state-of-the-art of 2D materials beyond graphene. Initially, we will outline the different chemical classes of 2D materials and discuss the various strategies to prepare single-layer, few-layer, and multilayer assembly materials in solution, on substrates, and on the wafer scale. Additionally, we present an experimental guide for identifying and characterizing single-layer-thick materials, as well as outlining emerging techniques that yield both local and global information. We describe the differences that occur in the electronic structure between the bulk and the single layer and discuss various methods of tuning their electronic properties by manipulating the surface. Finally, we highlight the properties and advantages of single-, few-, and many-layer 2D materials in...