Browsing by Author "Egap, Eilaf"
Now showing 1 - 4 of 4
Results Per Page
Sort Options
Item Direct triplet sensitization of oligothiophene by quantum dots(Royal Society of Chemistry, 2019) Xu, Zihao; Jin, Tao; Huang, Yiming; Mulla, Karimulla; Evangelista, Francesco A.; Egap, Eilaf; Lian, TianquanEffective sensitization of triplet states is essential to many applications, including triplet–triplet annihilation based photon upconversion schemes. This work demonstrates successful triplet sensitization of a CdSe quantum dot (QD)–bound oligothiophene carboxylic acid (T6). Transient absorption spectroscopy provides direct evidence of Dexter-type triplet energy transfer from the QD to the acceptor without populating the singlet excited state or charge transfer intermediates. Analysis of T6 concentration dependent triplet formation kinetics shows that the intrinsic triplet energy transfer rate in 1[thin space (1/6-em)]:[thin space (1/6-em)]1 QD–T6 complexes is 0.077 ns−1 and the apparent transfer rate and efficiency can be improved by increasing the acceptor binding strength. This work demonstrates a new class of triplet acceptor molecules for QD-based upconversion systems that are more stable and tunable than the extensively studied polyacenes.Item Metal Oxide Catalysts for the Synthesis of Covalent Organic Frameworks and One-Step Preparation of Covalent Organic Framework-Based Composites(American Chemical Society, 2021) Zhu, Yifan; Zhu, Dongyang; Yan, Qianqian; Gao, Guanhui; Xu, Jianan; Liu, Yifeng; Alahakoon, Sampath B.; Rahman, Muhammad M.; Ajayan, Pulickel M.; Egap, Eilaf; Verduzco, Rafael; Nanosystems Engineering Research Center for Nanotechnology-Enabled Water TreatmentThe integration of covalent organic frameworks (COFs) with inorganic materials provides opportunities to develop a new class of composite materials with high surface areas and novel functionalities relevant to photocatalysis, chemical adsorption, and magnetic resonance imaging. However, current methods for the preparation of COF-based composites require challenging, multistep synthetic protocols. Herein, we report a one-pot synthesis approach using a wide range of metal oxides to catalyze the synthesis of highly crystalline and porous COFs. We found that a large variety of metal oxides served as effective catalysts for the synthesis of imine COFs, including niobium(V) oxide (Nb2O5), nickel(II) oxide (NiO), manganese(IV) dioxide (MnO2), ruthenium(IV) oxide (RuO2), zinc(II) oxide (ZnO), lead(II) oxide (PbO), tellurium(IV) dioxide (TeO2), tin(IV) oxide (SnO2), manganese(III) oxide (Mn2O3), zirconium(IV) dioxide (ZrO2), and aluminum(III) oxide (Al2O3). Nb2O5 was effective for the synthesis of a wide range of COFs with different functional groups and pore sizes, and these reactions produced a metal oxide/COF composite. By using Fe3O4 nanoparticles (NPs) as the catalyst, we produced COF-based nanocomposites with Fe3O4 NPs distributed throughout the final COF product. The Fe3O4/COF nanocomposite had a high surface area of 2196 m2 g–1. This work demonstrates a class of novel, low-cost catalysts for synthesizing COFs and a new approach to produce metal oxide/COF composite materials.Item Photocontrolled polymerization induced by semiconducting nanomaterials(2021-07-30) Zhu, Yifan; Egap, Eilaf; Lou, JunDirect capture of solar energy for chemical transformation via photocatalysis proves to be a cost-effective and energy-saving approach to construct organic compounds. With the recent thriving in photosynthesis, photopolymerization has been established as a robust strategy for the production of specialty polymers with complex structures, precise molecular weight, and narrow dispersity. A key challenge in photopolymerization is the scarcity of effective photomediators (photoinitiators, photocatalysts, et.al) that can provide polymerization with high yield and well-defined polymer products. Current efforts on developing photomediators have mainly focused on organic dyes and metal complexes. However, most of the developed PCs consist of metals or organic dyes that often require elaborate synthetic protocols and purification steps to tune the redox potential and electronic properties. Therefore, the development of robust new generation PCs for photoinduced polymerization is of general interest. Nanomaterials (NMs), particularly semiconducting nanomaterials (SNMs) are suitable candidates for photochemical reactions due to their unique optical and electrical properties, such as high absorption coefficients, large charge diffusion lengths and broad absorption spectra. The objective of this thesis is to develop fundamentally new, versatile, externally regulated and controlled photomediated polymerization for the synthesis of insulating polymers and functional polymeric materials using light-triggered semiconducting nanoparticles (SNMs). Specific Aim 1 is to manipulating the ligand shell of semiconducting quantum dots (QDs) to enhance their photocatalytic performance in photopolymerization and provide a structure-relationship guideline for surface chemistry design (Chapter 2). Specific Aim 2 is to fabricate functional polymer-QDs hybrid materials with our well-developed methodologies(Chapter 3 and Chapter 4). Specific Aim 3 is to discover robust nanomaterial photoredox catalysts for near-infrared light-mediated living polymerization (Chapter 5).Item Solution processing approaches towards stretchable electronics and semiconducting polymer morphology modification(2021-08-13) Su, Zhe; Egap, EilafThe past decade has witnessed significant developments in stretchable electronics. Developing effective, low fabrication threshold and simple solution processing approaches will advance the development of stretchable electronics. Current solution processing approaches in the fabrication of stretchable electronics are mainly focused on spin coating and spray coating methods, which are simple but require complicated preliminary mask preparation. On the other hand, one modified three-dimensional (3D) printing-based solution processing method is a suitable candidate to fabricate stretchable electronics in a simple, flexible, and cost-effective way. Bar coating method is also a promising replacement for spin or spray coating to improve the alignment of nanostructures and modify charge carrier transport in naphthalene diimide (NDI)-based semiconducting polymer. However, research toward this modified 3D printing technique in stretchable electronics and bar coating-based solution processing approach of NDI-based semiconducting polymers is rare and limited. Therefore, we propose that 3D printing-based solution processing approach could serve as a novel and effective way to reduce the fabrication threshold of stretchable electronics and bar coating method has the potential to improve nanostructure alignment and is promising in modifying charge carrier transport of NDI-based semiconducting polymer films. This thesis focuses on investigations of fundamentally new, low fabrication threshold and effective solution processing approaches to fabricate stretchable electronics and improve transistor performance.