Vertical Phase Separation in Poly(3‐hexylthiophene): Fullerene Derivative Blends and its Advantage for Inverted Structure Solar Cells

A method which enables the investigation of the buried interfaces without altering the properties of the polymer films is used to study vertical phase separation of spin‐coated poly(3‐hexylthiophene) (P3HT):fullerene derivative blends. X‐ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM) analysis reveals the P3HT enrichment at the free (air) surfaces and abundance of fullerene derivatives at the organic/substrate interfaces. The vertical phase separation is attributed to the surface energy difference of the components and their interactions with the substrates. This inhomogeneous distribution of the donor and acceptor components significantly affects photovoltaic device performance and makes the inverted device structure a promising choice.     

Effects of Annealing on the Nanomorphology and Performance of Poly(alkylthiophene):Fullerene Bulk‐Heterojunction Solar Cells

The evolution of nanomorphology within thin solid‐state films of poly(3‐alkylthiophene):[6,6]‐phenyl‐C₆₁ butyric acid methyl ester (P3AT:PCBM) blends during the film formation and subsequent thermal annealing is reported. In detail, the influence of the P3AT's alkyl side chain length on the polymer/fullerene phase separation is discussed. Butyl, hexyl, octyl, decyl, and dodecyl side groups are investigated. All of the P3ATs used were regioregular. To elucidate the nanomorphology, atomic force microscopy (AFM), X‐ray diffraction, and optical spectroscopy are applied. Furthermore, photovoltaic devices of each of the different P3ATs have been constructed, characterized, and correlated with the nanostructure of the blends. It is proposed that the thermal‐annealing step, commonly applied to these P3AT:PCBM blend films, controls two main issues at the same time: a) the crystallization of P3AT and b) the phase separation and diffusion of PCBM. The results show that PCBM diffusion is the main limiting process for reaching high device performances.     

Energetics of carbon nanotubes

We have investigated the energetics of carbon nanotubes. Calculations have been performed by using the empirical many-body potential energy function developed by Tersoff for carbon. Received: 30 March 1998 / Accepted: 28 July 1998     

富勒烯的功率光限幅特性

应用时间分辨技术研究了富勒烯溶液的激发态吸收瞬态功率光限幅特性,在实验条件下,其功率光限幅的开关速度约为5 ns.     

A Soluble Donor–Acceptor Double-Cable Polymer: Polythiophene with Pendant Fullerenes

Summary.  We report the synthesis and the spectroscopic properties of a novel soluble thiophene-based copolymer carrying pendant fullerene moieties (donor–acceptor double-cable polymer). Photoinduced absorption (PIA) experiments on spin cast films reveal a photoinduced electron transfer from the polythiophene chain onto the fullerene moieties. The performance of photovoltaic devices produced with this copolymer is also discussed. Corresponding author. E-mail: antonio.cravino@jku.at Received August 16, 2002; accepted (revised) August 26, 2002     

Why fluorinate fullerenes?

This review explores the reasons for fluorinating fullerenes, describes mechanistic deductions from studies carried out to date, explores future directions, and evaluates applications to large-scale preparative chemistry. Some previous structural characterisations are updated in the light of more recent data and interpretations.     

Super-slippery carbon nanotubes

The friction between the walls of multi-wall carbon nanotubes is shown to be extremely low in general, with important details related to the specific choice of the walls. This is governed by a simple expression revealing that the phenomenon is a profound consequence of the specific symmetry breaking: super-slippery sliding of the incommensurate walls is a Goldstone mode. Three universal principles of tribology, offering a recipe for lubricant selection are emphasized. Received 8 August 2001     

Fullerene formation in atmospheric pressure opposed flow oxy-flames

Samples of condensable material from opposed flow diffusion flames of methane and acetylene and oxygen enriched air at atmospheric pressure were collected and analyzed by high-pressure liquid chromatography to determine the fullerene yield. High resolution transmission electron microscopy studies revealed the presence of fullerenes and well-defined carbon layers with various degrees of curvature. Results show that fullerene formation strongly increases with the acetylene content in the fuel. Increasing strain rate positively affects the fullerene content in the condensable material; higher strain rate flames favor fullerenes over soot, indicating lower fullerene consumption by soot due to lower soot concentration. If the oxygen content in the oxidizing oxygen/nitrogen mixture is increased, fullerene concentration increases due to the higher temperatures and higher precursor concentration. Similar relative variations of fullerene concentrations with flame conditions are predicted by the numerical model. However, the absolute concentrations of fullerenes are, in general, underpredicted by 4 orders of magnitude. This result can be partially attributed to uncertainties in the rate coefficients for H-abstraction and C₂H₂-addition. This discrepancy also suggests that other important fullerene formation pathways are to be included in the numerical model.     

Synthesis of C60/[10]CPP-Catenanes by Regioselective,Nanocapsule-Templated Bingel Bis-Addition

The addition of two unsymmetric malonate esters to the Buckminster fullerene C₆₀ can lead to 22 spectroscopically distinguishable isomeric products and therefore represents a formidable synthesis challenge. In this work, we achieve 87 % selectivity for the formation of a single (in,out-trans-3) isomer by combining three approaches: (i) we use a starting material, in which the two malonates are covalently connected (tether approach); (ii) we form the strong supramolecular complex of C₆₀ with the shape-persistent [10]CPP macrocycle (template approach) and (iii) we embed this complex further within a self-assembled nanocapsule (shadow mask approach). Variation of the spacer chain shed light on the limitations of the approach and the ring dynamics in the unusual [2]catenanes were studied in silico with atomistic resolution. This work significantly widens the scope of mechanically interlocked architectures comprising cycloparaphenylenes (CPP).     

Analysis of fullerene-based nanomaterial in serum matrix by CE

With the increasing interest in using nanoparticles as vehicles for drug delivery and image contrast agents, there is a need to develop assays for their detection and quantitation in complex matrices to facilitate monitoring their biodistribution. In this study, we developed a CE approach for the analysis of two nanoparticles: carboxyfullerene (C3) and dendrofullerene (DF1) in both standard solutions and a serum matrix. These highly soluble, charged C(60) derivatives were characterized by CZE using either a bare or dynamically coated fused-silica capillaries. The resolution of both nanoparticles was slightly lower with the coated capillary; however, their migration times were faster. While separation of the DF1 nanoparticles using MEKC resulted in a greater number of observable peaks, the peak profile of C3 was basically unchanged regardless of whether SDS micelles were added to the running buffers or not. The MEKC and/or CZE assays were then used to quantitate the C3 and DF1 nanoparticles in spiked human serum samples. The quantitation of the nanoparticles was linear from 0-500 microg/mL with detection limits ranging from 0.5 to 6 microg/mL.