A Photovoltaic C60-Si Heterojunction

A heterojunction was prepared by depositing a thin film of C₆₀ on a p-Si substrate. Photovoltaic properties were observed using a UV-filtered solar simulator and natural sun light. Surface Photovoltage Spectroscopy was employed to distinguish between the nature of photoconversion in the C₆₀ and Si layers.     

基于p+-Si与n-ZnO纳米线的p-n异质结的制备及其性质研究

利用CVD蒸汽俘获法，在p^＋硅片上制备了垂直生长的n型ZnO纳米线阵列，用XRD和SEM分析了样品的结构与形貌。测试发现样品的I-V曲线符合典型的p-n异质结特性，正向开启电压为0．5V，反向饱和电流为0．02mA。计算了异质结的理想因子η，发现当异质结两端偏压在0V-0．3V的低压区域，理想因子为1．85，而在0．3v-0．8v的高偏压区域，理想因子为8．36。解释了理想因子偏高的原因是由于金属一半导体接触以及ZnO纳米线与p^＋-si界而存在缺陷。     

Intramolecular Negative-Effect in the Alkali-Metal-Doped C60; A2C60 and A4C60

It is investigated theoretically why alkali-metal-doped C₆₀, A_xC₆₀, is a nonmagnetic semiconductor for x=2 and 4. We find that this is the consequence of the intramolecular negative- U effect due to the strong electron-phonon interaction and the weak Hund coupling between conduction electrons.     

Au电极作用下C60、2C60与4C60富勒烯分子的电子传输特性

采用扩展的Hückel方法与格林函数方法,研究了Au电极作用下,C60富勒烯、2C60和4C60聚合体分子的电子结构与导电性,并对它们的电子结构与电子输运特性进行了对比.研究结果表明,C60、2C60或4C60富勒烯分子与Au电极 "接触"后,其HOMO、LUMO间的能隙减小;C60、2C60或4C60分子与Au电极之间的结合既有共价键的成分,又有离子键的成分,其中,C60、4C60分子与Au电极结合的离子键特征更为明显;三种富勒烯分子的电子输运性能依次具有C60>2C60>4C60分子的顺序.     

A Study of Interaction of Dopants in C60: Doping Alkali-Halogen-Alkali into C60 in Successive Steps

It is well established that for an alkali-doped C₆₀ sample to be superconducting, the oxidation state C ^3– ₆₀ must be satisfied. It has been found previously that T _c is proportional to crystal parameter a in a face-centered cubic (fcc) structure. It is thus desirable to intercalate the largest possible size of molecule that can contribute one electron into every interstitial space. The successful process of such doping depends on our understanding the interaction among the dopants and C₆₀. We introduce a fabrication scheme of three steps successive doping using alkali (A) and halogen (H) elements along this line. While A ₃C₆₀ is superconducting, A _3–x (AH) _x C₆₀ was found to be non-superconducting in the second step and the sample became superconducting again after doping with A, leading to stoichiometric ratio of A _3–x (AH) _x A _x C₆₀. We present an explanation based on interaction among dopants and C₆₀ and analyze the process of ionization of dopants, which is consistent with our experimental finding reported here.     

Ozonides and Oxides of C60 and C70: A Review

This paper presents a literature review of studies of ozonides and oxides of C₆₀ and C₇₀.     

Band Gaps of Na2C60 and K4C60

respectively.     

Rb3C60单晶薄膜制备及Rb3C60/C60相界面稳定性研究

通过控制蒸发源电流、源和样品间距及扩散时间,室温下在C60单晶(111)解理面上制备出Rb3C60.用低温同步辐射角分辨光电子谱测量了样品的能带结构.观察到的能带色散表明样品为单晶薄膜.用X光电子谱首次研究了Rb3C60与C60相界面的稳定性.结果表明温度低于约420 K时界面是稳定的.     

ESR Studies on C60.OX and C60.HMTTEF

Abstract

The electron spin resonance (esr) of C₆₀.O_x and C₆₀.HMTTEF (hexamethylentetratellurafulvalene) has been investigated at 9.36 GHz as a function of temperature. T (298 T 4 K). C₆₀.O_x shows an esr absorption of equal ‘g’ value to that of C₆₀ exposed to O₂ and light but is more intense. The C₆₀ in its pure form is in a singlet state. The impurity sites introduced by O₂ produce the esr absorption. The Curie - Weiss plots of inverse esr absorption intensity versus temperature indicate an antiferromagnetic TH = 50 for air exposed C₆₀ and 90K for C₆₀O_x. From the esr intensity at room temperature, the calculated number of free spins (S = 1/2) is =1/3 per mole of C_60-O_x. In case of C₆₀.HMTTEF, there is a very weak esr absorption at room temperature suggesting that the room temperature form is diamagnetic with very small charge transfer between C₆₀ and HMTTEF. This conclusion is consistent with the structure and magnetic susceptibility of this cocrystal. As the temperature is lowered, the equilibrium: AD <=> A?^? + D?⁺ is displaced towards the formation of free radical species, A?^? and D?⁺.     

C60 Dimers Revisited

Abstract

Several dimers: C₁₂₀, C₁₄₀, C₁₃₀ and their oxygen‐containing derivatives as well as some oligomers or polymers of the well known spherical fullerenes have been synthesized so far. Some of the formulas attributed to such compounds represent the first steps in a more complex fate leading to trivalent capped tubulenes. Such a way could even be followed by functionalized fullerenes. A detailed network transformation is given for C₆₀ and its mono‐ and di‐epoxy derivatives. Semiempirical calculations support the presented findings.     

Solubility of C60

All the published data on the solubility of C₆₀ in 140 organic and inorganic solvents are summarized and the critical features of the experimental techniques are treated. Data on die temperature dependence of solubility are also listed and analyzed. Experimental evidences on the molecular state of dissolved C₆₀ as well as the interactions between the solute and solvents are discussed.     

C60 Dimers Revisited

Several dimers: C₁₂₀, C₁₄₀, C₁₃₀ and their oxygen-containing derivatives as well as some oligomers or polymers of the well known spherical fullerenes have been synthesized so far. Some of the formulas attributed to such compounds represent the first steps in a more complex fate leading to trivalent capped tubulenes. Such a way could even be followed by functionalized fullerenes. A detailed network transformation is given for C₆₀ and its mono- and di-epoxy derivatives. Semiempirical calculations support the presented findings.     

C32C60C180、C60@C180富勒烯分子的压缩力学特性

采用Tersoff-Brenner势与L—J势的分子动力学方法，研究了双石墨层作用下C32、C60、C180以及C60@C180富勒烯分子的压缩力学特性。根据计算结果，讨论了几种富勒烯压缩过程中的变形、能量、压缩栽荷等的变化及其差异。研究表明，由于分子几何构形上的差异，压缩时，C180出现了明显的“塌陷”现象，“塌陷”过程中，能量及外载荷一度下降；几种富勒烯压缩时的能量吸收能力排序为：C32〉C60〉C60@C180〉C180，承载能力的排序为：C60@C180〉C180〉C60〉C32。     

SIMULTANEOUS DETERMINATION OF C60 AND C70 FULLERENES BY A SPECTROPHOTOMETRIC METHOD

In all fullerene-producing systems, reaction products were black soot extracts reported to contain a 5-25% fullerene mixture. Toluene extraction of the soot results in a solution of C₆₀, C₇₀, and higherc fullerenes. Without separation, absolute determination of the contents is not possible, leaving the researcher to comment only on the C₆₀/C₇₀ ratio of the solution. High-performance liquid chromatography, nuclear magnetic resonance, and scanning tunneling microscopy imaging techniques were reported in the literature for determining the C₆₀/C₇₀ ratio of the mixtures. These methods require tedious experiments and produce slightly differing results as well. In this communication, a new and relatively quick method is proposed for the simultaneous determination of the yields of C₆₀ and C₇₀ (not the ratio) in fullerene-containing solutions by ultraviolet-visible spectrophotometric analysis.     

Growth and Characterization of C60 Crystals from Pure C60 and Fullerite

Good quality C₆₀ crystals have been grown from high purity C₆₀ powder and fullerene mixture (C₆₀/C₇₀) by vacuum sublimation method. The grown crystals were characterized with Optical microscopy, SEM, powder XRD, High Performance Liquid Chromatography and Raman spectroscopic analyses.     

Effects of Mechanical Grinding on C60 And Ca5C60 Superconductor

Abstract

The effects of mechanical grinding on polycrystalline C₆₀ and Ca₅C₆₀ superconductor are examined. It has been found that mechanical grinding may severely degrade phases of C₆₀ (fcc) and Ca₅C₆₀ (sc). The grinding destroys the long-range ordering of crystals and produces a partial amorphous state. The damage of crystal leads to the disappearance of superconductivity for Ca₅C₆₀. The samples with an amorphous phase can be recrystallized by annealing at 600°C for pure C₆₀ and Ca₅C₆₀. Magnetic susceptibility measurements indicated that the superconductivity of the degraded sample did not recover easily to the initial state.