Tim S. Jones

The University of Warwick · Department of Chemistry

The surface stability of coinage metals is paramount when they are used as electrode materials for functional electronic devices incorporating organic semiconductors. Here, adsorption of non-planar vanadyl phthalocyanine molecules on Cu(110) drastically restructures the metal surface at room temperature (RT) that is further enhanced upon moderate a...

We report here the temperature-dependent incorporation kinetics of dimeric arsenic in InAs(001) homoepitaxy, using reflection high-energy electron diffraction (RHEED). Surface reconstructions, in combination with the RHEED investigation have provided insight into the growth of InAs(001), developing an accurate method of controlling the V:III ratio,...

Invited for the cover of this issue is a collaboration between the groups of D. Bonifazi (University of Namur, Cardiff University), A. De Vita (King's College London), and G. Costantini (University of Warwick). The shape of a scanning tunneling microscopy image of filament structures formed when pyrene 4,5,9,10-tetraone is co-deposited with iron on...

Supplementary

The pyrene 4,5,9,10-tetraone (PTO) molecule spontaneously forms two-dimensional metal–organic nanostructures with atoms from the substrate when deposited on a Cu(111) surface or with iron atoms if Fe is co-deposited with PTO. The nanostructures are stabilized by the coordination of individual metallic atoms by the molecule's strongly electronegativ...

Two-dimensional metal-organic nanostructures based on the binding of ketone groups and metal atoms were fabricated by depositing pyrene-4,5,9,10-tetraone (PTO) molecules on a Cu(111) surface. The strongly electronegative ketone moieties bind to either copper adatoms from the substrate or codeposited iron atoms. In the former case, scanning tunnelli...

Copper (I) iodide (CuI) thin films are employed as a structural templating layer for the growth of metal-free phthalocyanine (H2Pc) thin films. Structural polymorphs are observed in x-ray diffraction patterns when micro-crystalline CuI films exhibiting copper and iodine terminated grains are used. Each polymorph is nucleated from a single terminati...

The performance of organic semiconductor thin films in electronic devices is related to their crystal structure and morphology, with charge transport mobility dependent on the degree of crystallinity and on the crystallographic orientation. Here organic molecular beam deposition of vanadyl phthalocyanine is studied on graphene and it is shown that...

The growth and characterisation of a non-planar phthalocyanine (vanadyl phthalocyanine, VOPc) on a complete monolayer (ML) of a planar phthalocyanine (Iron(ii) phthalocyanine, FePc) on an Au(111) surface, has been investigated using ultra-high vacuum (UHV) scanning tunnelling microscopy (STM) and low energy electron diffraction (LEED). The surface...

The spectroscopic and nonlinear optical properties of the positional isomers of metal free 4α-(4-tert-butylphenoxy) phthalocyanine are presented. Second order nonlinear polarizability (β), imaginary hyperpolarizability (Im(γ)) and imaginary susceptibility (Im[χ(3)]) values were determined for the four positional isomers. The measured β values of th...

Interfacial layers are commonly employed in organic photovoltaic (OPV) cells in order to improve device performance. These layers must be transparent, stable, be compatible with the photo-active materials and provide efficient charge extraction with a good energetic match to the relevant organic material. In this report we demonstrate the compatibi...

Metal oxide thin films are increasingly utilized in small molecular organic photovoltaic devices to facilitate electron transport and injection. Despite this there is little understanding of the influence these layers have on the structure of adjacent organic semiconductor layers. Here we use both O- and Zn-terminated (0001) single crystal zinc oxi...

The transition between the a(1 × 3) and c(4 × 4) surface reconstructions of InSb(0 0 1) has been carefully monitored by reflection high energy electron diffraction as a function of temperature and Sb2 flux, without incident In flux. Arrhenius-like behaviour is observed across the whole range of Sb2 fluxes and temperatures, allowing accurate interna...

Molecular template growth (MTG) is a newly developed method for fabricating high-quality organic semiconductor thin films with controllable morphologies, molecular orientations, electronic structures, and interface properties to produce high-performance organic electronic and optoelectronic devices. There are several MTG methods with different mole...

Using conductive atomic force microscopy, we introduce a method to simultaneously acquire electrical space charge limited current measurements and material properties such as Young's modulus and surface adhesion, with nanoscale resolution. We demonstrate the utility of this method using thin films of the prototypical, semiconducting polymer poly-3-...

Recent requirements for low cost energy solutions have led to increased research in the area of organic photovoltaics (OPVs), on account of their potential flexibility, low cost and large scale manufacture. The success of these devices, however, has been hampered by low carrier mobilities, resulting in poorly performing devices. Whilst bulk propert...

We study the roughening process and morphology transition of organic semiconductor thin film induced by molecular orientation in the model of molecular semiconductor copper hexadecafluorophthalocyanine (F16CuPc) using both experiment and simulation. The growth behaviour of F16CuPc thin film with the thickness, D, on SiO2 substrate takes on two proc...

We report the direct deposition of indium antimonide, by molecular beam epitaxy (MBE) on gallium antimonide, resulting in the formation of quantum dots (QDs) with a maximum density of ~5.3×10^10 cm−2. Using reflection high energy electron diffraction (RHEED) and atomic force microscopy (AFM) for the analysis of samples with InSb depositions of 1–6...

A new evaporable electron acceptor material for organic photovoltaics based on N-ethyl barbituric acid bithiophene (EBB) has been demonstrated. Bilayer devices fabricated with this non-fullerene acceptor and boron subphthalocyanine chloride (SubPc) donor produce power conversion efficiencies as high as 2.6% with an extremely large open-circuit volt...

The incorporation of Bi in alloys grown by molecular beam epitaxy is investigated as a function of Bi flux at fixed growth temperature (275 °C) and growth rate . The Bi content is found to vary proportionally with Bi flux with Bi contents, as measured by Rutherford backscattering, in the range . The GaSbBi samples grown at the lowest Bi fluxes have...

Solution-grown copper iodide crystals are used as substrates for the templated growth of the nonplanar vanadyl phthalocyanine using organic molecular beam deposition. Structural characterization reveals a single molecular orientation produced by the (111) Miller plane of the copper iodide crystals. These fundamental measurements show the importance...

The unique electronic properties and functional tunability of polycyclic aromatic hydrocarbons have recently fostered high hopes for their use in flexible, green, portable and cheap technologies. Most applications require the deposition of thin molecular films onto conductive electrodes. The growth of the first few molecular layers represents a cru...

Elevated substrate temperature growth of phthalocyanine thin films is known to influence film morphology and increase crystallinity. Structural templating offers another method through which the structure of phthalocyanine films can be controlled. Here we combine the use of copper iodide (CuI) and elevated substrate temperatures and investigate the...

Two photoluminescence (PL) peaks were observed in temperature-dependent PL spectra of GaSb1−xBix layers with 0 < x ≤ 0.042. The high-energy (HE) peak was found to be associated with the bandgap-related emission in GaSb1−xBix, since its energy corresponds to the bandgap determined from photoreflectance measurements. The low-energy (LE) peak was attr...

The properties of molecular beam epitaxy-grown InSb 1− x Bi x alloys are investigated. Rutherford backscattering spectrometry shows that the Bi content increases from 0.6% for growth at 350 °C to 2.4% at 200 °C. X-ray diffraction indicates Bi-induced lattice dilation and suggests a zinc-blende InBi lattice parameter of 6.626 Å. Scanning electron m...

Morphological and structural control of organic semiconductors through structural templating is an efficient route by which to tune their physical properties. The preparation and characterisation of iron phthalocyanine (FePc) / copper iodide (CuI) bilayers at elevated substrate temperatures is presented. Thin CuI (111) layers are prepared which are...

In this work, a thin ZnSe layer was deposited in vacuum and then thermally annealed in air to provide an efficient electron extraction layer for an inverted organic photovoltaic (OPV) cell. Annealing the ZnSe film at 450 °C (ZnSe(450 °C)) increased the device performance and gave an efficiency of 2.83%. X-ray photoelectron spectroscopy (XPS) measur...

Understanding the growth of organic semiconductors on solid surfaces is of key importance for the field of organic electronics. Non planar phthalocyanines have shown great promise in organic photovoltaic (OPV) applications, but little of the fundamental surface characterization to understand their structure and properties has been performed. Acquir...

Indium tin oxide (ITO)-free organic photovoltaic (OPV) devices were fabricated using highly conductive poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) as the transparent conductive electrode (TCE). The intrinsic conductivity of the PEDOT:PSS films was improved by two different dimethyl sulfoxide (DMSO) treatments - (i) DMSO was...

Molecular beam epitaxy is used to grow Ga1-yInySb1-xBix (y <= 5.5% and x <= 2.5%) and AlyGa1-ySb1-xBix alloys (y <= 6.6% and x <= 2.0%). The alloy composition and film thickness are determined by high resolution x-ray diffraction. The band gap of the alloys is determined by photomodulated reflectance (PR) spectroscopy. The band gap energy reduces w...

Photoreflectance (PR) spectroscopy was applied to study the band gap in GaSb1−xBix alloys with Bi < 5%. Obtained results have been interpreted in the context of ab initio electronic band structure calculations in which the supercell (SC) based calculations are joined with the alchemical mixing (AM) approximation applied to a single atom in the cell...

We demonstrate hybrid organic photovoltaic (HOPV) bilayer devices with very high open circuit voltages (VOC) of 1.18 V based on a sol-gel processed zinc oxide (ZnO) acceptor and a vacuum deposited boron subphthalocyanine chloride (SubPc) donor layer. X-ray photoelectron spectroscopy (XPS) and Kelvin Probe (KP) measurements of the ZnO/SubPc interfac...

Two borazine derivatives have been synthesised to investigate their self-assembly behaviour on Au(111) and Cu(111) surfaces by scanning tunnelling microscopy (STM) and theoretical simulations. Both borazines form extended 2D networks upon adsorption on both substrates at room temperature. Whereas the more compact triphenyl borazine 1 arranges into...

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The epitaxial growth, structural, and optical properties of GaSb1–xBix alloys have been investigated. The Bi incorporation into GaSb is varied in the range 0 < x ≤ 9.6% by varying the growth rate (0.31–1.33 μm h−1) at two growth temperatures (250 and 275 °C). The Bi content is inversely proportional to the growth rate, but with higher Bi contents a...

Structural templating of organic semiconductors affords control of out-of-plane film structure and molecular orientation with respect to solid surfaces. Herein we use a prototypical copper iodide (CuI)/planar phthalocyanine system to produce detailed surface and crystal structure information using atomic force microscopy (AFM) and X-ray diffraction...

In this paper, we discuss the use of the typical electron-donor (donor) material boron subphthalocyanine chloride (Cl-BsubPc) and a chlorinated derivative (hexachloro boron subphthalocyanine chloride, Cl-Cl(6)BsubPc) to act as electron-accepting (acceptor) materials and as replacements for Cap when coupled with tetracene and pentacene as the electr...

GaSb1-xBix layers with 0 < x ≤ 0.042 have been studied by photoreflectance in 15–290 K temperature range. We found that due to the incorporation of Bi atoms into the GaSb host, the E0 band gap-related transition redshifts (∼30 meV per 1% Bi) and significantly broadens. The shift of the E0 transition in the temperature range 10–270 K has been found...

We have studied the element and orbital-specific electronic structure of thin films of 3,4,9,10-perylene-tetracarboxylic-dianhydride (PTCDA) using a combination of synchrotron radiation-exited resonant x-ray emission spectroscopy, x-ray absorption spectroscopy, x-ray photoelectron spectroscopy, as well as density functional theory calculations. Res...

Spray deposition is currently attracting significant attention as a low cost method for organic photovoltaic (OPV) device fabrication. We report indium tin oxide (ITO)-free small moleule OPV devices comparing spin coated and spray deposited highly conductive poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) as the transparent cond...

We report a new method for introducing metal atoms into silicon wafers, using negligible thermal budget. Molecular thin films are irradiated with ultra-violet light releasing metal species into the semiconductor substrate. Secondary ion mass spectrometry and x-ray absorption spectroscopy show that Mn is incorporated into Si as an interstitial dopan...

Molecular-beam epitaxy has been used to grow GaSb1-xBix alloys with x up to 0.05. The Bi content, lattice expansion, and film thickness were determined by Rutherford backscattering and x-ray diffraction, which also indicate high crystallinity and that >98% of the Bi atoms are substitutional. The observed Bi-induced lattice dilation is consistent wi...

We report an improvement in power conversion efficiency in a small molecule tandem organic photovoltaic (OPV) device by the optimisation of current balancing of the sub-cells using an optical spacer layer. A co-deposited layer of N,N'-bis(1-naphthyl)-N,N'-diphenyl-1,1'-biphenyl-4,4'-diamine (alpha-NPD) and molybdenum oxide was used as the optical s...

The optical properties of GaNSb alloys with N contents of up to 2.5% have been investigated at room temperature using infrared absorption spectroscopy. The evolution of the absorption onsets with N content has been described using a three level band anticrossing model of the N localized states interactions with the GaSb conduction band. This approa...

It's a kind of magic: Hydroxy pentaaryl borazine molecules self-assemble into small clusters on Cu(111) surfaces, whereas with symmetric hexaaryl borazine molecules large islands are obtained. Simulations indicate that the observed "magic" cluster sizes result from long-range repulsive Coulomb forces arising from the deprotonation of the BOH group...

The N content of a series of GaNSb samples grown by molecular-beam epitaxy is investigated using high-resolution x-ray diffraction (HRXRD) and secondary-ion mass spectrometry. The N contents determined by the two methods agree well at lower N compositions (x < 0.01), and deviate significantly at larger N contents (x > 0.02). Analysis of the HRXRD-d...

We calculate the electronic structure and exchange interactions in a copper(II)phthalocyanine (Cu(II)Pc) crystal as a one-dimensional molecular chain using hybrid exchange density functional theory (DFT). In addition, the intermolecular exchange interactions are also calculated in a molec-ular dimer using Green's function perturbation theory (GFPT)...

The epitaxial growth of GaN by Plasma Assisted Molecular Beam Epitaxy was investigated by Scanning Tunnelling Microscope (STM). The GaN film was grown on initial GaN (0001) and monitored by in situ Reflection High Energy Electron Diffraction and STM during the growth. The STM characterization was carried out on different sub-films with increased th...

Low power electronics are an ideal application for organic photovoltaics (OPV) where a low-cost OPV device can be integrated directly with a battery to provide a constant power source. We demonstrate ultra-high voltage small molecule multijunction devices with open circuit voltage (VOC) values of up to 7V. Optical modelling is employed to aid the o...

The incorporation of N into MBE grown GaNSb and GaInNSb is investigated. Measurements of the N fraction in GaNSb show the familiar linear dependence on inverse growth rate, followed by a departure from this at low growth rates; a similar behaviour is observed for GaInNSb. Unexpectedly, the point at which there is a departure from this linear behavi...

The structural and magnetic properties of F 16 CuPc thin films and powder, including x-ray diffraction (XRD), superconducting quantum interference device (SQUID) magnetometry, and theoretical modelling of exchange interactions are reported. Analysis of XRD from films, with thickness ranging between 100 and 160 nm, deposited onto Kapton and a peryle...

The structural and magnetic properties of F 16 CuPc thin films and powder, including x-ray diffraction (XRD), superconducting quantum interference device (SQUID) magnetometry, and theoretical modelling of exchange interactions are reported. Analysis of XRD from films, with thickness ranging between 100 and 160 nm, deposited onto Kapton and a peryle...

We report a method of fabricating a high work function, solution processable vanadium oxide (V2Ox(sol)) hole-extracting layer. The atmospheric processing conditions of film preparation have a critical influence on the electronic structure and stoichiometry of the V2Ox(sol), with a direct impact on organic photovoltaic (OPV) cell performance. Combin...

We calculate the electronic structure and exchange interactions in a copper(II)phthalocyanine (Cu(II)Pc) crystal as a one-dimensional molecular chain using hybrid exchange density functional theory (DFT). In addition, the intermolecular exchange interactions are also calculated in a molecular dimer using Green's function perturbation theory (GFPT)...

The orientation of the constituent molecules in organic thin film devices can affect significantly their performance due to the highly anisotropic nature of π-conjugated molecules. We report here an angle dependent x-ray absorption study of the control of such molecular orientation using well-ordered interlayers for the case of a bilayer heterojunc...

Electron microscopy and diffraction are used to examine the nanoscale structure and molecular orientation in molecular films down to nominally monolayer thickness. The films studied consist of the planar n-type molecular semiconductor copper hexadecafluorophthalocyanine (F16CuPc) directly deposited onto graphene oxide (GO) membranes by organic mole...

High-efficiency fullerene-free single-heterojunction (SHJ) organic photovoltaic (OPV) cells consisting of tetracene (Tc) as a typical donor material and boron subphthalocyanine chloride (SubPc) as an acceptor material are reported. Cells containing SubPc as a direct replacement for C60 exhibit an ∼60% improvement in open circuit voltage (Voc) achie...

The theoretical understanding of exchange interactions in organics provides a key foundation for quantum molecular magnetism. Recent SQUID magnetometry of a well know organic semiconductor, copper-phthalocyanine [1,2] (CuPc) shows that it forms quasi-one-dimensional spin chains. Green's function perturbation theory calculation [3] is used to find t...

Atomic resolution scanning tunneling microscopy (STM) has been used to study the asymmetric-(1×3) and c(4×4) Sb-terminated reconstructions of InSb(100). STM images show that these are examples of ordered and disordered reconstructions respectively. The c(4×4) structure involves the chemisorption of excess Sb onto an already Sb-terminated surface wi...

Atomic resolution scanning tunneling microscopy (STM) has been used to study the Asterminated (2×4) and c(4×4) reconstructions formed on GaAs(001) surfaces grown in situ by molecular beam epitaxy (MBE). Filled states STM images of the (2×4) surface always showed unit cells consisting of two As dimers in the top layer. Cooling this surface under an...

We demonstrate organic discrete heterojunction photovoltaic cells based on fullerene (C60) and copper hexadecafluorophthalocyanine (F16CuPc), in which the C60 and F16CuPc act as the electron donor and the electron acceptor, respectively. The C60/F16CuPc cells fabricated with conventional and inverted architectures both exhibit comparable power conv...

White light bias External Quantum Efficiency (EQE) measurements made on organic tandem cells are demonstrated to provide a quick and direct measurement of current-balancing. EQE measurements under white light bias can therefore be used to help guide or measure optimisation in asymmetric multi-junction cells.

A systematic study of the effect of the zinc oxide (ZnO) electrodeposition parameters (concentration, temperature, potential and pH) on film morphology, thickness, transparency, roughness and crystallographic orientation is presented with the view of producing optimized thin, planar, and continuous ZnO films for photovoltaic applications. Electroch...

Electrodeposition of highly crystalline ZnO nanostructures directly onto copper phthalocyanine and pentacene thin films, from aqueous solutions containing zinc nitrate and dissolved oxygen, has been successfully demonstrated for the first time using a two-step electrochemical deposition process. Importantly, surface activation of the molecular thin...

The incorporation of N in molecular-beam epitaxy of GaNxSb1−x alloys with x ⩽ 0.022 has been investigated as a function of temperature (325–400°C) and growth rate 0.25–1.6 μmh−1. At fixed growth rate, the incorporated N fraction increases as the temperature is reduced until a maximum N content for the particular growth rate reached. At each tempera...

We report increased cell performance for boron subphthalocyanine chloride (SubPc)/fullerene (C60) organic photovoltaic (OPV) cells when thermally evaporated vanadium oxide (V2OX) thin films are incorporated as a hole-extracting layer at the indium-tin oxide (ITO)/SubPc interface. Ultra-violet photoemission spectroscopy (UPS) studies of the V2OX fil...

We present a new generic method to synthesize nanostructured metal(II) oxide films on a substrate such as silicon. Vacuum ultraviolet (VUV) excimer lamps rupture metal–organic precursors, creating volatile organic fragments, while the metal species at the surface form oxides. X-ray photoemission spectroscopy (XPS) and X-ray absorption spectroscopy...

A rapid, solvent free method for the fabrication of highly transparent ultrathin (∼8 nm) Au films on glass has been developed. This is achieved by derivatizing the glass surface with a mixed monolayer of 3-mercaptopropyl(trim­ethoxysilane) and 3-aminopropyl(trimethoxysilane) via co-deposition from the vapor phase, prior to Au deposition by thermal...

By tuning the frontier orbital energies through selective halogenation of the periphery of the organic framework, new light harvesting electron acceptors based on boron subphthalocyanine chloride (SubPc) have been made. Planar heterojunction organic photovoltaics made using a Cl 6-SubPc acceptor deliver an exceptionally high open-circuit voltage (∼...

We report that through the incorporation of polar self-assembled monolayers (SAMs) at the indiumtin oxide (ITO)/donor interface in chloroaluminium phthalocyanine (ClAlPc)/C60 discrete heterojunction organic photovoltaic (OPV) cells, the power conversion efficiency can be dramatically increased. This enhanced performance is due to better alignment b...

Nanowire-array films of the molecular semiconductor, copper hexadecafluorophthalocyanine (F16CuPc), have been fabricated by templated growth on a pre-deposited planar perylene-3,4,9,10-tetracarboxylic-3,4,9,10-dianhydride (PTCDA) layer. The PTCDA template induces the F16CuPc molecules to adopt a new type of lying-down arrangement with the molecular...

We present a detailed investigation of the molecular orientation transition and resulting morphology of copper hexadecafluorophthalocyanine (F16CuPc) thin films induced by solvent annealing. The F16CuPc molecules reorganize from small spherical or fibre-like crystals to large-size ribbon crystals which then dominate the resulting film properties. T...

Organic photovoltaic (OPV) planar heterojunction devices based on an aqueous solution processed 3,4′,4′′,4′′′-copper(II) phthalocyanine-tetrasulfonic acid tetrasodium salt (TSCuPc) donor layer and a fullerene (C60) acceptor have been fabricated demonstrating power conversion efficiencies of up to 0.32% and an open circuit voltage (VOC) of almost 0....

Free base phthalocyanine films have been grown on glass substrates by organic molecular beam deposition. In situ post-growth annealing of the samples leads to the α → β1 transformation. Different transition states have been identified and their morphological properties studied by atomic force and optical microscopy. The transition occurs via a disc...

Powder X-Ray diffraction (XRD) has been used to study multilayered structures grown by organic molecular beam deposition based on the molecular materials PTCDA and metal-free phthalocyanine (H2Pc). Double layers of different polymorphic forms (α β1 and β2) of H2Pc indicate that the structure of the second layer is determined by the properties of th...

We report a significant increase in the open circuit voltage (Voc) and power conversion efficiency in both chloroaluminium phthalocyanine (ClAlPc)/fullerene (C60) and boron subphthalocyanine chloride (SubPc)/C60 organic photovoltaic (OPV) cells with the insertion of a thin molybdenum oxide (MoOx) hole-extracting layer. This improvement was not seen...

The formation of three-dimensionally interconnected donor–acceptor nanocomposites from copper(II) phthalocyanine tetrasulfonic tetrasodium salt (tsCuPc) and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) is reported. Thin films were formed using a multi-step template-directed growth method. The nanocomposites consist of crystalline, continuous a...

The surface structures of copper phthalocyanine (CuPc) thin films deposited on sulphur-passivated and plane perylene-3,4,9,10-tetracarboxylic dianhydride (PTCDA)-covered InAs(100) surfaces have been studied by low energy electron diffraction (LEED) and van der Waals (vdW) intermolecular interaction energy calculations. The annealing to 300 o C and...

We demonstrate that the molecular semiconductor, copper hexadecafluorophthalocyanine (F16CuPc), can be used as an electron accepting layer in bilayer small molecule organic photovoltaic (OPV) cells using boron subphthalocyanine chloride (SubPc) as the electron donor. The F16CuPc/SubPc cells show good overall performance and stability, with a power...

The structure−function relationship of organic photovoltaic (OPV) cells based on the chloroaluminum phthalocyanine (ClAlPc)/fullerene (C60) planar heterojunction are explored. Optimization is achieved with the use of a molybdenum oxide (MoOx) and an underlying 3,4,9,10-perylene tetracarboxylic acid (PTCDA) interlayer at the hole extracting electrod...

The operation of discrete heterojunction organic photovoltaic (OPV) cells employing chloro-aluminium phthalocyanine (ClAlPc) as the electron donor and C as the electron acceptor is reported and the characteristics are correlated with the energy level structure of the devices determined using X-ray photoelectron spectroscopy. The results give new in...

We report a new method for introducing metal atoms into silicon wafers, using negligible thermal budget. Molecular thin films are irradiated with ultra-violet light releasing metal species into the semiconductor substrate. Secondary ion mass spectrometry and x-ray absorption spectroscopy show that Mn is incorporated into Si as an interstitial dopan...

The interface electronic structure of a bilayer heterojunction of C 60 and three different phthalocyanines grown on indium tin oxide (ITO) has been studied using synchrotron radiation-excited photoelectron spectroscopy. The energy difference between the highest occupied molecular orbital level of the phthalocyanine (donor) layer and the lowest unoc...

We report a 60% increase in open circuit voltage (Voc) and power conversion efficiency in a chloroaluminium phthalocyanine (ClAlPc)/fullerene (C60) planar heterojunction photovoltaic device after insertion of a MoO3 hole-extracting layer at the interface between the indium tin oxide (ITO) electrode and the ClAlPc donor layer, with an associated imp...

Intermediate band solar cells (IBSC) have emerged as an alternative design for solar cells that can dramatically increase power conversion efficiency. Here, it is demonstrated that a k.p multiband theory with periodic boundary conditions can easily be applied to predict electronic and absorption characteristics of the semiconductor QD arrays that...