Research into the evaporation of solutions is not only aimed at a better understanding the physics of evaporation, but increasingly at capitalizing on the extremely simple method it offers to assemble diverse nonvolatile solutes into complex ordered structures on the submicron and longer length scales. This Review highlights recent advances in evaporative assembly of confined solutions, focusing especially on recently developed approaches that provide structures with unprecedented regularity composed of polymers, nanoparticles, and biomaterials, by controlled evaporation-driven, flow-aided self-assembly. A broad range of variables that can control the deposition are explored and the future directions of this rich field are presented.

https://lib.dr.iastate.edu/cgi/viewcontent.cgi?article=3345&context=etd

Learning from "coffee rings": ordered structures enabled by controlled evaporative self-assembly.

Background: Synthetic nanoparticles are emerging as versatile tools in biomedical applications, particularly in the area of biomedical imaging. Nanoparticles 1 – 100 nm in diameter have dimensions comparable to biological functional units. Diverse surface chemistries, unique magnetic properties, tunable absorption and emission properties, and recent advances in the synthesis and engineering of various nanoparticles suggest their potential as probes for early detection of diseases such as cancer. Surface functionalization has expanded further the potential of nanoparticles as probes for molecular imaging. Objective: To summarize emerging research of nanoparticles for biomedical imaging with increased selectivity and reduced nonspecific uptake with increased spatial resolution containing stabilizers conjugated with targeting ligands. Methods: This review summarizes recent technological advances in the synthesis of various nanoparticle probes, and surveys methods to improve the targeting of nanoparticles for...

Nanoparticles for biomedical imaging

Self-organized, freestanding titania (TiO2) membrane with ultrahigh aspect ratio of the length/diameter (∼1500) was fabricated via electrochemical anodization of highly pure titanium (Ti) foil in fluorine-containing ethylene glycol, followed by a simple and safe detachment of the formed TiO2 membrane from the metallic Ti substrate. The resulting membrane consists of highly ordered, vertically aligned, one-side open TiO2 nanotube arrays. The pore diameter, wall thickness, and length of the nanotube arrays are 90 nm, 15 nm, and 135 µm, respectively, at a certain anodization condition.

http://nanofm.mse.gatech.edu/Papers/Wang%20J%20and%20Lin%20ZQ,%20Chem%20Mater,%2020,%201257,%202008.pdf

Freestanding TiO2 Nanotube Arrays with Ultrahigh Aspect Ratio via Electrochemical Anodization

Extending the spectral absorption of organolead halide perovskite solar cells from visible into near-infrared (NIR) range renders the minimization of non-absorption loss of solar photons with improved energy alignment. Herein, we report on, for the first time, a viable strategy of capitalizing on judiciously synthesized monodisperse NaYF4:Yb/Er upconversion nanoparticles (UCNPs) as the mesoporous electrode for CH3NH3PbI3 perovskite solar cells and more importantly confer perovskite solar cells to be operative under NIR light. Uniform NaYF4:Yb/Er UCNPs are first crafted by employing rationally designed double hydrophilic star-like poly(acrylic acid)-block-poly(ethylene oxide) (PAA-b-PEO) diblock copolymer as nanoreactor, imparting the solubility of UCNPs and the tunability of film porosity during the manufacturing process. The subsequent incorporation of NaYF4:Yb/Er UCNPs as the mesoporous electrode led to a high efficiency of 17.8 %, which was further increased to 18.1 % upon NIR irradiation. The in situ integration of upconversion materials as functional components of perovskite solar cells offers the expanded flexibility for engineering the device architecture and broadening the solar spectral use.

Monodisperse Dual‐Functional Upconversion Nanoparticles Enabled Near‐Infrared Organolead Halide Perovskite Solar Cells

Nanochemistry and nanomaterials provide numerous opportunities for a new generation of photovoltaics with high solar energy conversion efficiencies at low fabrication cost. Quantum-confined nanomaterials and polymer–inorganic nanocomposites can be tailored to harvest sun light over a broad range of the spectrum, while plasmonic structures offer effective ways to reduce the thickness of light-absorbing layers. Multiple exciton generation, singlet exciton fission, photon down-conversion, and photon up-conversion realized in nanostructures, create significant interest for harvesting underutilized ultraviolet and currently unutilized infrared photons. Nanochemical interface engineering of nanoparticle surfaces and junction-interfaces enable enhanced charge separation and collection. In this review, we survey these recent advances employed to introduce new concepts for improving the solar energy conversion efficiency, and reduce the device fabrication cost in photovoltaic technologies. The review concludes with a summary of contributions already made by nanochemistry. It then describes the challenges and opportunities in photovoltaics where the chemical community can play a vital role.

Nanochemistry and nanomaterials for photovoltaics.

Nanocomposites of poly(3-hexylthiophene)−cadmium selenide (P3HT−CdSe) were synthesized by directly grafting vinyl-terminated P3HT onto [(4-bromophenyl)methyl]dioctylphosphine oxide (DOPO-Br)-functionalized CdSe quantum dot (QD) surfaces via a mild palladium-catalyzed Heck coupling, thereby dispensing with the need for ligand exchange chemistry. The resulting P3HT−CdSe nanocomposites possess a well-defined interface, thus significantly promoting the dispersion of CdSe within the P3HT matrix and facilitating the electronic interaction between these two components. The photophysical properties of nanocomposites were found to differ from the conventional composites in which P3HT and CdSe QDs were physically mixed. Solid-state emission spectra of nanocomposites suggested the charge transfer from P3HT to CdSe QDs, while the energy transfer from 3.5 nm CdSe QD to P3HT was implicated in the P3HT/CdSe composites. A faster decay in lifetime further confirmed the occurrence of charge transfer in P3HT−CdSe nanocompos...

https://lib.dr.iastate.edu/cgi/viewcontent.cgi?article=1566&context=chem_pubs

Jung Wang

Papers

Organic−Inorganic Nanocomposites via Directly Grafting Conjugated Polymers onto Quantum Dots