Search results for "fullerene"
showing 10 items of 197 documents
Carbon-Based Nanomaterials in Analytical Chemistry
2019
Ruthenium pentamethylcyclopentadienyl mesitylene dimer: a sublimable n-dopant and electron buffer layer for efficient n-i-p perovskite solar cells
2019
Electron-transport materials such as fullerenes are widely used in perovskite solar cells to selectively transfer the photogenerated electrons to the electrodes. In order to minimize losses at the interface between the fullerene and the electrode, it is important to reduce the energy difference between the transport level of the two materials. A common approach to reduce such energy mismatch is to increase the charge carrier density in the semiconductor through doping. A variety of molecular dopants have been reported to reduce (n-dope) fullerenes. However, most of them are either difficult to process or extremely air sensitive, with most n-dopants leading to the formation of undesirable si…
Modeling epitaxial film growth of C$_{60}$ revisited
2020
Epitaxial films evolve on time and length scales that are inaccessible to atomistic computer simulation methods like molecular dynamics (MD). To numerically predict properties for such systems, a common strategy is to employ kinetic Monte Carlo simulations, for which one needs to know the transition rates of the involved elementary steps. The main challenge is thus to formulate a consistent model for the set of transition rates and to determine its parameters. Here, we revisit a well-studied model system, the epitaxial film growth of the fullerene ${\mathrm{C}}_{60}$ on an ordered ${\mathrm{C}}_{60}$ substrate (111). We implement a systematic multiscale approach in which we determine transi…
Stability of C60 and N@C60 under thermal and optical exposure
2015
N@C60, a nitrogen atom encapsulated in a fullerene shell, has an electron-nuclear spin system with outstanding coherence properties attractive for quantum computation. The stability of this molecule is known to be limited due to thermal escape of the nitrogen atom from the C60 cage but little is known about the stability towards optical excitation, which is one possible tool for an indirect scheme to manipulate and read out quantum information. Here, we report the results of a systematic study regarding thermal and optical effects on the stability of N@C60. The central result is that stability under intense laser irradiation can be obtained when the sample remains cooled below a certain tem…
Modified nanocarbons as catalysts in organic processes
2019
The application of nanocarbons as useful scaffolds for the production of a wide range of catalytic systems is an ever-growing field as witnessed by the huge amount of research on this topic. Both covalent and non-covalent modifications of nanocarbons represent the main routes to gain access to hybrid nanostructured catalysts. In this chapter the attention will be focused on nanocarbons, namely, fullerene, nanotubes, and graphene, employed for catalytic purposes covering both organocatalytic and metal-based (metal nanoparticles, organometallic complexes) reactions, whereas simple physical mixtures of nanocarbons and metal nanoparticles as well as examples dealing with electrocatalysis or pho…
Graphene, Fullerenes, Carbon Nanotubes: Electronic Subsystem
2017
This chapter introduces the reader to the analysis of the structural and electronic system properties of various carbon allotropes (CNT, graphene) and several molecular derivatives. The genesis of the electronic system formation is investigated in detail. Non-regular defected nanocarbon systems are considered for possible applications in different fields, including energy storage; chemical, biochemical and electrochemical sensing; water purification; and catalysis.
Fullerene imposed high open-circuit voltage in efficient perovskite based solar cells
2016
Five different commercially available fullerenes are evaluated as hole blocking/electron transporting materials in p–i–n methylammonium lead iodide perovskite solar cells using a vacuum deposited perovskite absorber layer. A significant enhancement of the solar cell performance can be obtained by selecting a suitable fullerene derivative. Open-circuit voltages as high as 1.11 volts are obtained leading to a power conversion efficiency of 14.6%.
New concepts and applications in macromolecular chemistry of fullerenes
2010
A new classification on the different types of fullerene-containing polymers is presented according to their different properties and applications they exhibit in a variety of fields. Because of their interest and novelty, water-soluble and biodegradable C(60)-polymers are discussed first, followed by polyfullerene-based membranes where unprecedented supramolecular structures are presented. Next are compounds that involve hybrid materials formed from fullerenes and other components such as silica, DNA, and carbon nanotubes (CNTs) where the most recent advances have been achieved. A most relevant topic is still that of C(60)-based donor-acceptor (D-A) polymers. Since their application in pho…
Quantum-Chemical Insights into the Self-Assembly of Carbon-Based Supramolecular Complexes
2018
Understanding how molecular systems self-assemble to form well-organized superstructures governed by noncovalent interactions is essential in the field of supramolecular chemistry. In the nanoscience context, the self-assembly of different carbon-based nanoforms (fullerenes, carbon nanotubes and graphene) with, in general, electron-donor molecular systems, has received increasing attention as a means of generating potential candidates for technological applications. In these carbon-based systems, a deep characterization of the supramolecular organization is crucial to establish an intimate relation between supramolecular structure and functionality. Detailed structural information on the se…
Meniscus coated high open-circuit voltage bi-layer solar cells
2012
Neat bi-layer solar cells of a fullerene acceptor and a cyanine dye donor were prepared using meniscus coating. Meniscus coating is very material efficient and leads to high quality pinhole-free films. The cells exhibit high open circuit voltages of 1 volt, only 0.8 eV below the band gap of the cyanine dye. This is one of the smallest differences reported for organic solar cells and illustrates an almost optimal donor-acceptor energy level alignment.