Vacancy Hole Research Articles

Study on the enhancement of device performance by the action of carbonohydrazide at the buried bottom interface of inverted mesoporous perovskite solar cells

The interface of perovskite solar cells (PSCs) significantly influences their efficiency and stability. Researchers tend to pay more attention to the upper surface of the perovskite absorber layer and conduct relatively less research on the bottom buried interface, mainly because the bottom of the perovskite film is challenging to peel off, which increases the difficulty of the characterization of the observation and analysis. Defects at the bottom interface make it more challenging to optimize the treatment than the upper surface. For inverted PSCs, the interface located in direct contact between the light absorption layer of perovskite and the hole transport layer is the buried interface. The buried interface is the direct interface for transporting charge carriers of PSCs and is also the center of non-radiative compound enrichment. The defect density is higher than the defect density of perovskite film crystal. Due to the DMSO initially left in the commonly used perovskite precursor solution during the film formation process, evaporation during the annealing and crystallization process creates vacancy holes at the bottom of the perovskite layer film. These holes and crystal boundaries tend to produce many non-radiative recombinations. These holes are also the sites of photodecomposition, leading to reduced efficiency and stability in PSCs, ultimately impacting the overall performance of PSCs. The work adds an Al2O3 mesoporous layer on top of the hole transport layer (HTL), which reduces the direct contact area between PTAA and perovskite film. In the perovskite precursor solution, we incorporate a solid additive called Carbonohydrazide (CBH), this substance replaces some of the DMSO and fills in the voids at the bottom of the perovskite film that is left when the DMSO evaporates. This process helps to reduce non-radiative recombination and photodegradation caused by the voids at the bottom of the perovskite, leading to an improvement in the efficiency and stability of the cell. The optimization of the buried bottom interface has improved the cell’s average efficiency from 17.6 % to 19.7 %, an 11.9 % increase. The aperture area of the devices in this work is 0.048 cm2, and the photoelectric conversion efficiency of our device still reaches 80.64 % of the initial efficiency after 600 h of continuous heating in a glove box with a nitrogen atmosphere, maintaining a test temperature of 60 °C.

Molecular Dynamics Analysis of Graphene Nanoelectromechanical Resonators Based on Vacancy Defects.

Due to the limitation of graphene processing technology, the prepared graphene inevitably contains various defects. The defects will have a particular influence on the macroscopic characteristics of the graphene. In this paper, the defect-based graphene nanoresonators are studied. In this study, the resonant properties of graphene were investigated via molecular dynamic simulations. The effect of vacancy defects and hole defects at different positions, numbers, and concentrations on the resonance frequency of graphene nanoribbons was studied. The results indicated that single monatomic vacancy has no effect on graphene resonant frequency, and the concentration of the resonant frequency of graphene decreases almost linearly with the increase of single-atom vacancy concentration. When the vacancy concentration is 5%, the resonance frequency is reduced by 12.77% compared to the perfect graphene. Holes on the graphene cause the resonance frequency to decrease. As the circular hole defect is closer to the center of the graphene nanoribbon, not only does its resonant frequency increase, but the tuning range is also expanded accordingly. Under the external force of 10.715 nN, the resonant frequency of graphene reaches 429.57 GHz when the circular hole is located at the center of the graphene nanoribbon, which is 40 GHz lower than that of single vacancy defect graphene. When the circular hole is close to the fixed end of graphene, the resonant frequency is 379.62 GHz, which is 90 GHz lower than that of single vacancy graphene. When the hole defect is at the center of nanoribbon, the frequency tunable range of graphene reaches 120 GHz. The tunable frequency range of graphene is 100.12 GHz when the hole defect is near the fixed ends of the graphene nanoribbon. This work is of great significance for design and performance optimization of graphene-based nanoelectro-mechanical system (NEMS) resonators.

Numerical Simulation of OXIDE-ION Blocking Effect in Hydrogen Permeable Metal-Supported Fuel Cell

Protonic ceramic fuel cells (PCFCs) have been drawing considerable attentions because of their potential for high-power operating at intermediate temperature (IT), 400–600°C, which is a salient issue for their practical implementation. BaZr0.1Ce0.7Y0.2O3, popular proton-conducting ceramic electrolyte material, has notably high conductivity of 9 × 10−3 S cm−1 at 500°C [1], but vast majority of power outputs in current PCFC literature still lag far behind 1.0 W cm−2 at the IT regime. In general, PCFCs have structure of porous anode support composed proton-conducting ceramic electrolyte and metallic Ni. Meanwhile, a hydrogen membrane fuel cell (HMFC), which consist of a dense hydrogen-permeable metal anode and kindred electrolyte material, has achieved extraordinary performances of 1.4 W cm−2 at 600°C [2]. This is higher than any others ever reported to the best of our knowledge. However, what give rise to such high performance is obscure. Here, we simulated effect of oxide-ion blocking at anode/electrolyte on defect profile in HMFC and compared them with those of PCFCs to elucidate origins of the high performance.The one-dimensional concentration profiles of three charged defect carriers: oxygen vacancy, proton, and oxygen hole at steady state were computed based on Nernst–Planck–Poisson model with defect thermodynamics of BaZr0.8Y0.2O3 [3]. In PCFC, membrane is equilibrated with O2, H2, and H2O gases. In HMFC, however, boundary conditions at the anodic surface are unknown since the surface is sealed by dense metal anode. We made an assumption that a flux of oxygen vacancy is kept at 0 inside the electrolyte membrane of HMFC [4].Simulations confirm that oxide-ion blocking at an electrolyte/anode interface greatly modifies the defects’ distribution across the membrane. Positively charged oxygen vacancies are depressed near electrolyte/anode interface owing to the oxide-ion blocking, and thus, protonic defects are alternatively accumulated near the regions for the charge neutrality preservation, which results in the enhancement of local proton conductivity (Attached image). Accordingly, the superior performance of HMFC to PCFC is attributable the proton pumping by utilizing the oxygen chemical potentials.

First-principles on the energy band mechanism for modifying conduction property of graphene nanomeshes

By means of first-principles electronic structure calculations, the ordered graphene nanomeshes with patterned hexagonal vacancy holes are theoretically studied to explore the modification mechanism of electrical conduction on graphene atomic monolayers. According to pseudopotential plane wave first-principles scheme based on density functional theory, the band structures of graphene nanomeshes are calculated to analyze the electrical conductance in correlation with the superlattice symmetry and vacancy hole magnetism. Based on the structural features and topological magnetism of Y-shaped nodes between the nanopores on the atomic monolayer of graphene, the graphene nanomeshes are classified into three types. The quadruplet degeneracy and splitting of electronic states at Brillouin zone center are investigated by comparing the band structures of graphene nanomeshes and analogical superlattices. The effects of inversion symmetry and supercell size on the opening band-gap at Dirac cone are elaborately analyzed with the consideration of antiferromagnetic coupling and hydrogen passivation at the magnetic edge of nanopores on graphene nanomeshes. The band-structure calculation results indicate that the (3<i>m</i>, 3<i>n</i>) (<i>m</i> and <i>n</i> are integers) superlattices have fourfold degenerate electronic states at center point of Brillouin zone, which can be effectively splitted by regularly arranging porous atomic vacancy to make the (3<i>m</i>, 3<i>n</i>) nanomesh, resulting in adjustable band-gap no matter whether or not the sublattices keeping in equivalence. In the nanomeshes formed by patterned holes with magnetic edge, the antiferromagnetic coupling adds a quantum parameter to the inversion symmetry so as to break the sublattice equivalence, opening band-gap at the twofold degenerate <i>K</i> point. Nevertheless, the hydrogen passivation at the edge of magnetic nanopores will convert the magnetic graphene nanomeshes into non-magnetic and eliminate the band-gap at <i>K</i> point. The band-gap of graphene nanomeshes could also be controlled by changing the density of nanopores, suggesting a graphene nanomaterial with adjustable band-gap that can be designed by controlling the mesh pore spacing. The graphene nanomeshes represent a new mechanism of forming band-gap and thus promise a strategy for achieving special electrical properties of graphene nanostructures. These results also theoretically demonstrate that the nano-graphene is a prospective candidate with flexibly adjustable electrical properties for realizing multivariate applications in new-generation nano-electronics.

Efficient sensitized photoluminescence of Er silicate in silicon oxide films embedded with amorphous silicon clusters, part II: photoluminescence

We report on the sensitized photoluminescence (PL) of Er silicates in a-Si-embedded Er silicate films. A two-step annealing process is utilized, where the first step determines the distribution and the sizes of the a-Si embedded structure and the second step modifies the crystal quality and the phase composition of Er silicates as well as the concentration of sensitizers. The determination of the annealing temperatures and the annealing time for each step requires an overall consideration of these factors. Optimized PL from Er silicates sensitized by luminescent centers (LCs) such as neutral oxygen vacancy (NOV) or non-bridging oxygen hole center (NBOHC) have been achieved in the film annealed at 1000 °C for 30 min followed by 1100 °C for 30 min, which is composed of well-crystallized y-Er2Si2O7 embedded with a-Si clusters.

Lifetime of the metastable P1/22 state of F-like Ar9+ isolated in a compact Penning trap

Multiply ionized atoms of a single charge state can be captured at low energy in a compact Penning trap, allowing the measurement of the radiative lifetime of an atomic state that decays via weakly allowed transitions. Such a measurement is reported here for the radiative decay lifetime of the metastable $^{2}P_{1/2}$ state in fluorinelike ${\mathrm{Ar}}^{9+}$, wherein the $n=2$ shell has only one vacancy (hole) in a $2p$ orbital. Highly ionized atoms are extracted from an electron beam ion trap and guided into the ion capture apparatus. Upon capturing the ${\mathrm{Ar}}^{9+}$ ions, light from the magnetic-dipole transition is detected with a photomultiplier tube and counted with a multichannel scaler. Using this technique, the radiative lifetime of the metastable $^{2}P_{1/2}$ state in ${\mathrm{Ar}}^{9+}\phantom{\rule{4pt}{0ex}}1{s}^{2}\phantom{\rule{0.16em}{0ex}}2{s}^{2}\phantom{\rule{0.16em}{0ex}}2{p}^{5}$ is measured to be $\ensuremath{\tau}=9.31\ifmmode\pm\else\textpm\fi{}0.08$ ms, consistent with a previous intra-EBIT measurement.

The Calculation of Negative Bias Illumination Stress-Induced Instability of Amorphous InGaZnO Thin-Film Transistors for Instability-Aware Design

We propose a systematic calculation method for negative bias illumination stress (NBIS)-induced instabilities in amorphous InGaZnO thin-film transistors (TFTs). The proposed method is based on activation energy window (AEW) in subgap energy range, and it can reproduce the NBIS time evolution of ${I}$ – ${V}$ characteristics without long-term stress test. Furthermore, it quantitatively explains the effect of oxygen content on the NBIS instability. The AEW, which is employed for emulating the oxygen vacancy ionization, peroxide formation, and hole trapping, has the order of magnitude of 1016–1017 cm−3 for the bias stress of −20 V and the commercial LED backlight of 300 cd/m2. The proposed method is expected to play such an important role in the instability awareness of amorphous oxide TFTs.

Cu:ZnS and Al:ZnS thin films prepared on FTO substrate by nebulized spray pyrolysis technique

Cu doped ZnS and Al doped ZnS thin films were coated on the fluorine-doped tin oxide substrates by nebulized spray pyrolysis technique. The structural, morphological, optical and electrical properties of Cu and Al doped ZnS thin films were investigated. X-ray diffraction analysis revealed that all the doped ZnS films are polycrystalline nature with hexagonal structure. The size of the crystallites was also determined. Field emission scanning microscopic images of the doped ZnS thin films shows smooth and uniform plaque shaped grains on to the surface of the films. Energy dispersive analysis of X-ray confirms the presence of expected elements without any other impurities and nature of the thin film. The optical transmittance values were observed to be 71 and 74% for Cu:ZnS and Al:ZnS films, respectively. The observed high band gap value is 3.67 eV for 2% Cu:ZnS film. The room temperature photoluminescence spectra of the Cu:ZnS films showed blue emission peaks at wavelength 407 and 422 nm. The visible emission band at 478 nm is due to the recombination of electrons in the sulphur vacancy level and holes in the zinc vacancy. Low resistivity value was observed at 4% Cu:ZnS film is explained by crystalline size and carrier concentration. The enhanced electrical properties behavior of Cu and Al doped ZnS thins film proposes for effective solar cell application.

Antituberculosis drugs degradation by UV-based advanced oxidation processes

Several advanced oxidation processes (AOPs) were investigated for the degradation of isoniazid (INH) and rifampicin (RIF) in aqueous solution: TiO2 and ZnO heterogeneous photocatalysis and homogeneous and heterogeneous UV-A photo-Fenton processes. Under optimized conditions (pH 6.0 and 500mgL−1 of photocatalyst) the UV-A TiO2-photocatalysis removed approximately 90% of INH and 60% of RIF at 60min. Under similar experimental conditions, the degradation efficiency of ZnO was significantly lower to INH. The low-cost UV-A homogeneous photo-Fenton process removed 70% of INH and 80% of RIF at 60min. Photo-Fenton process using iron-immobilized in chitosan beads showed lower degradation efficiency (7% to INH and 50% to RIF) probably due to low iron availability in the catalyst surface. A radical scavenging assay was performed to investigate the effect of free radicals (hydroxyl radical (OH), electron vacancy (hole, h+), superoxide radical anions (O2−), and singlet oxygen (1O2)) on INH and RIF degradation during TiO2/UV-A photocatalysis. The two drugs have distinct degradation mechanisms, while RIF is degraded by h+, INH suffers influence of various active species. The TiO2/UV-A photocatalysis was employed to degrade INH/RIF residue.

Synthesis and characterization of Sr0.75Y0.25Co0.9Ru0.1O3−δ perovskite as a solid oxide fuel cell cathode material

The oxygen-deficient Sr0.75Y0.25Co0.9Ru0.1O3−δ (SYCR) cathode is systematically evaluated for the application of solid oxide fuel cells. X-ray diffraction analysis indicates that SYCR presents a tetragonal structure with space group of I4/mmm (139). In the measured high oxygen partial pressure (pO2) region (0.01–0.21 atm), the conductivity increases with increasing pO2 because of the oxygen vacancy annihilation and hole creation, relating to a general p-type semiconducting mechanism. To get an insight into the rate-limiting step of SYCR cathode, behaviors of individual polarization resistance (R 1 and R 2) are investigated in different pO2. The obtained fitting results reveal that R 1 is nearly independent on the pO2, while R 2 presents a (pO2)−0.5 dependence. At 800 °C, SYCR cathode exhibits an R p value of 0.14 Ω cm2, moreover, when using the wet hydrogen (∼ 3% H2O) as fuel and ambient air as oxidant, the maximum power density of single cell Ni-YSZ (yttria-stabilized zirconia)|YSZ|SYCR reaches 452.9 W cm−2.

Radiation-Induced Damage In Quartz At the Arrow Uranium Deposit, Southwestern Athabasca Basin, Saskatchewan

Abstract Radiation-induced damage in quartz from the overlying Athabasca Supergroup sandstones and the basement host rocks at the Arrow uranium deposit in the southwestern margin of the Athabasca basin, Saskatchewan, has been investigated by electron paramagnetic resonance (EPR) spectroscopy as well as cathodoluminescence (CL) imaging and spectroscopy. Powder EPR spectra confirm that quartz from the Arrow deposit contains a suite of radiation-induced defects, including characteristic silicon vacancy hole centers formed from bombardment of α particles emitted from the radioactive decay of U, Th, and their daughter isotopes. The EPR intensity distribution of α particle-induced defects in detrital quartz close to the sandstone–basement unconformity suggests that uranium-bearing fluids at Arrow are restricted to areas directly above the basement-hosted mineralization. Pink quartz in the basement, which occurs as veins and breccias in spatial association with uranium mineralization, is characterized by elevated, homogeneously distributed radiation-induced defects, suggesting its crystallization from uranium-bearing fluids most likely linked to the main mineralization event. Smoky quartz in veins and cavities often exhibits characteristic α particle-induced CL rims, which crosscut the growth zoning and apparently record late uranium remobilization. Abundant radiation-induced defects in the basement at the Arrow deposit are restricted to quartz within ∼7 m from uranium mineralization, confirming structurally controlled fluid flows. These results highlight the application of radiation-induced defects in quartz for determining the loci of uranium-bearing fluids.

Surface modification of reduced graphene oxide film by Ti ion implantation technique for high dye-sensitized solar cells performance

Titanium (Ti) ion implantation approach was used in the present study to modify the reduced graphene oxide nanosheet (rGO NS) by incorporating the Ti4+ ion (at various applied powers ranging from 50 to 250W) onto the rGO NS to prepare photoanodes for Dye-Sensitized Solar Cell (DSSC). The surface morphologies, functional groups, optical properties and surface chemical states of the modified rGO based photoanode (rGO-TiO2 nanocomposite (NC)) were studied. Fourier transform infrared (FTIR) spectra coupled with the elemental/chemical states in X-ray photoelectron spectroscopy (XPS) analysis revealed the presence of Ti–O–C functional groups after the modification process. Besides, the average size of Ti ion was found to be 70–80nm as incorporated with rGO NS. The spacing of anatase TiO2 onto rGO NS were reported as 0.35nm and 0.34nm under HRTEM analysis, respectively. Experimental result implied that 150W was the optimum applied power for the surface modification to take place ascribed to the lowest possibility for the recombination to occur and the smallest energy band gap. On top of that, at 150W, the electron transfer rate was also found to be the highest due to the highest availability of the carbon-atom vacancy holes for Ti4+ replacement. It was also discovered that the optimized power conversion efficiency (PCE) of 8.51% could be achieved in DSSC by implanting the Ti ion onto rGO NS-based photoanode using 150W. Further increase of the applied power to 200W or 250W led to the undesirable recombination of the Ti ions and rGO NS due to the exceptional photocatalytic activity among N719 dye/rGO/TiO2 interfaces which interfered the charge transportation at the KI electrolyte/N719 dye/rGO/TiO2 interfaces.

Electro-Chemo-Mechanical Studies of Perovskite-Structured Mixed Ionic-Electronic Conducting SrSn1-XFexO3-x/2+d

High efficiency and fuel flexibility make solid oxide fuel cells (SOFCs) attractive for conversion of fuels to electricity. Reduced operating temperatures, desirable for reduced costs and extended operation, however result in significant losses in efficiency. This has been traced primarily to slow cathode surface reaction kinetics. In this work, we extended previous studies on the promising mixed ionic and electronic conducting perovskite-structured SrTi1-xFexO3-x/2+δ (STF) materials system whose exchange kinetics were correlated with the minority electron charge density by replacing Ti with Sn, due to its distinct band structure and higher electron mobility. Oxygen nonstoichiometry and defect chemistry of the SrSn1-xFexO3-x/2+δ (SSF) system were examined by thermogravimetry as a function of oxygen partial pressure in the temperature range of 973-1273 K. Marginally higher reducibility was observed compared to corresponding compositions in STF system. The bulk electrical conductivity was measured in parallel to examine how changes in defect chemistry and electronic band structure associated with the substitution of Ti by Sn impact carrier density and ultimately electrode performance. Bulk chemical expansion was measured by dilatometry as a function of oxygen partial pressure while surface kinetics were examined by means of AC impedance spectroscopy. The electro-chemo-mechanical properties of SSF were found not to differ significantly from the corresponding composition in STF. Key thermodynamic and kinetic parameters for SrSn0.65Fe0.35O2.825+δ (SSF35) were derived including the reduction enthalpy, high electronic band gap, anion Frenkel enthalpy, oxygen vacancy migration energy, electron and hole mobilities. Though slightly shifted by Sn’s larger size, the defect equilibria and the cathode area specific resistance differed only in a limited way from those in STF. This was attributed to properties being largely dominated by Fe and not by the substitution of Ti with Sn.

Cathodoluminescence study of radiative interface defects in thermally grown SiO2/4H-SiC(0001) structures

Radiative defects in thermally grown SiO2/4H-SiC(0001) structures and their location in depth were investigated by means of cathodoluminescence spectroscopy. It was found that while luminescence peaks ascribed to oxygen vacancy and nonbridging oxygen hole centers were observed both from thermal oxides grown on (0001) Si-face and C-face surfaces as with thermal oxides on Si, intense yellow luminescence at a wavelength of around 600 nm was identified only from the oxide interface on the Si-face substrate regardless of the oxide thickness and dopant type. Possible physical origins of the radiative centers localized near an oxide interface of a few nm thick are discussed on the basis of visible light emission from Si backbone structures.

The abnormal electrical and optical properties in Na and Ni codoped BiFeO3 nanoparticles

Bi0.97Na0.03Fe1−xNixO3 (x = 0, 0.005, 0.01, 0.015) nanoparticles are prepared via a sol-gel method. Weak ferromagnetism and exchange bias phenomenon without field cooling are observed in the samples. The oxygen vacancy concentration and leakage current density are increased with increasing the Ni content. However, with the increase of Ni content, the band gap of Bi0.97Na0.03Fe1−xNixO3 nanoparticles first decreases and then increases. To explain the abnormal phenomenon, the interplay of oxygen vacancy donor and hole acceptor is analyzed and a phenomenological qualitative model based on the electronic energy band is proposed. Additionally, the threshold switching behavior appears in Bi0.97Na0.03Fe1−xNixO3 samples with x = 0.01, 0.015 and the effect is qualitatively explained by introducing a conducting channel model based on the high-density mobile charges.

Structure, bonding, and passivation of single carbon-related oxide hole traps near 4H-SiC/SiO2 interfaces

Single carbon interstitial in silicon dioxide, existing in carboxyl configuration, is shown to act as a border hole trap near 4H-SiC/SiO2 interface. Using density functional theory-based formation energy considerations, it is found to switch charge state between +2 and neutral as the 4H-SiC Fermi level sweeps its charge transition level located 1.4 eV above 4H-SiC valence band edge. Thus, carboxyl defect is predicted to be a potential candidate for threshold voltage instability in 4H-SiC MOSFETs. Post oxidation annealing of the interface with nitric oxide is shown to remove carboxyl defects. However, treating the defect in H2 creates a hole trap level at 1.1 eV above 4H-SiC valence band edge similar to the original carboxyl defect. The stability of carboxyl and H2 treated carboxyl defects in their doubly positive state is explained on the basis of their structural and bonding transformations during hole capture. These include puckering and back-bonding of silicon with lattice oxygen as in the well-known oxygen vacancy (E′ center) hole traps and an increase in the bond order between carboxyl carbon and oxygen.

Electrocatalysis Involving High Temperature Proton-Conducting Oxides: Intriguing Experimental Observations & Theoretical Implications

High temperature proton conducting oxides were discovered in the 1980s, and they exhibit, depending on temperature and atmosphere, conduction of proton as well as oxygen vacancy and electron hole at temperatures of ~400-900 oC. From electrocatalysis point of view, the conduction of proton together with oxygen vacancy and hole present new opportunity to tailor the electrode reaction process for high temperature electrochemical reactions, which could provide, sometimes surprisingly, new features that may benefit efficient energy conversion and chemical production. Using the electrochemical system of solid oxide fuel cells (SOFC) as an example, this presentation will show incorporating proton conducting oxides as electrolyte and/or (part of) the electrodes in SOFC leads to interesting experimental observations such as improved resistance to poisoning by hydrogen sulfide (H2S), better resistance to deactivation by deposition of carbon, and higher open circuit voltage. The theoretical implications of these intriguing observations will be discussed in terms of the possible changes in the underlying electrochemical reaction mechanisms, and the directions for future research will be pointed out.

Mechanism of Metal Catalyzed Healing of Large Structural Defects in Graphene

Structural defects are almost unavoidable in graphene synthesis and they may significantly deteriorate the performance of graphene in applications. Although defects of small sizes may be easily healed by the rearrangement of a few C atoms near the defect site, the healing of large ones is rather complicated and the healing mechanism remains unclear. In this work, we reveal a catalytic healing of large structural defects in graphene based on both classical molecular dynamics simulations and density functional theory calculations. The kinetic healing processes of large vacancy holes in graphene with and without a nickel catalyst are explored. Our results show that the presence of a single Ni atom can (1) catalyze the dissociation of carbon feedstock, (2) heal nonhexagonal C rings formed during the addition of C atoms, and (3) prevent the formation of hanging C chains and arching C patches, and ultimately lead to the successful healing of large structural defects in graphene.

Fluorescence induced by double K capture

Features of double fluorescence spectra generated by double K capture in the 78Kr atom are considered. The energies and bandwidths of fluorescence are calculated. The latter are approximately four times wider for the first and second quanta, respectively, relative to the vacancy hole in the K shell. The fluorescence yields are calculated as well. They are 0.77 and 0.61 for the first and second quanta, respectively, and 0.47 for both quanta simultaneously.

Optimal Electron Doping of aC60Monolayer on Cu(111) via Interface Reconstruction

We demonstrate the charge state of C60 on a Cu(111) surface can be made optimal, i.e., forming C60(3-) as required for superconductivity in bulk alkali-doped C60, purely through interface reconstruction rather than with foreign dopants. We link the origin of the C60(3-) charge state to a reconstructed interface with ordered (4x4) 7-atom vacancy holes in the surface. In contrast, C60 adsorbed on unreconstructed Cu(111) receives a much smaller amount of electrons. Our results illustrate a definitive interface effect that affects the electronic properties of molecule-electrode contact.