Carbon nanotube surfaces, activated and randomly decorated with metal nanoclusters, have been studied in uniquely combined theoretical and experimental approaches as prototypes for molecular recognition. The key concept is to shape metallic clusters that donate or accept a fractional charge upon adsorption of a target molecule, and modify the electron transport in the nanotube. The present work focuses on a simple system, carbon nanotubes with gold clusters. The nature of the gold-nanotube interaction is studied using first-principles techniques. The numerical simulations predict the binding and diffusion energies of gold atoms at the tube surface, including realistic atomic models for defects potentially present at the nanotube surface. The atomic structure of the gold nanoclusters and their effect on the intrinsic electronic quantum transport properties of the nanotube are also predicted. Experimentally, multi-wall CNTs are decorated with gold clusters using (1) vacuum evaporation, after activation with an RF oxygen plasma and (2) colloid solution injected into an RF atmospheric plasma; the hybrid systems are accurately characterized using XPS and TEM techniques. The response of gas sensors based on these nano(2)hybrids is quantified for the detection of toxic species like NO(2), CO, C(2)H(5)OH and C(2)H(4).

Thin film solar cells based on nontoxic and earth-abundant elements are necessary for future-generation photovoltaic devices. Tin monosulfide is a promising candidate that can be used as an absorber material in thin film photovoltaics. In this paper, we introduce the direct synthesis of stoichiometric and single-phase p-type SnS films via the electrodeposition from the ionic liquid 1-butyl-3-methylimidazolium dicyanamide ([C4mim][DCA]) containing elemental sulfur and SnCl2 at high temperature. The electrochemical behavior is studied, and a deposition mechanism of tin monosulfide from the elemental sulfur saturated ionic liquid is proposed. XRD, XPS, and Raman spectroscopy demonstrate the sole presence of α-SnS without any secondary sulfide phases (e.g., SnS2, Sn2S3). XPS depth profiling confirmed the phase purity and disproved the presence of organic contamination in the as-deposited films. Photoelectrochemical measurements affirmed the p-type conductivity of the SnS films. The as-deposited layers have an indirect optical band gap at 1.17 eV and high optical absorption (α ≥ 104 cm–1) at photon energy above 1.4 eV. First solar cells with a standard thin film substrate cell configuration are presented.

For the first time, the plasma‐assisted inkjet printing of metal‐organic decomposition (MOD) inks is demonstrated to provide an easily up‐scalable method toward the deposition of highly conductive silver features on paper. Atmospheric plasma sintering methods provide a fast and effective alternative to thermal treatment. This high‐speed, room‐temperature approach ensures the immediate conversion of the MOD inks after printing and thus overcomes wetting issues typically encountered in porous substrates—a mechanical solution to a chemical problem.

Alkali metal doping is essential to achieve highly efficient energy conversion in Cu(In,Ga)Se 2 (CIGSe) solar cells. Doping is normally achieved through solid state reactions, but recent observations of gasphase alkali transport in the kesterite sulfide (Cu 2 ZnSnS 4 ) system (re)open the way to a novel gas-phase doping strategy. However, the current understanding of gas-phase alkali transport is very limited. This work (i) shows that CIGSe device efficiency can be improved from 2% to 8% by gas-phase sodium incorporation alone, (ii) identifies the most likely routes for gas-phase alkali transport based on mass spectrometric studies, (iii) provides thermochemical computations to rationalize the observations and (iv) critically discusses the subject literature with the aim to better understand the chemical basis of the phenomenon. These results suggest that accidental alkali metal doping occurs all the time, that a controlled vapor pressure of alkali metal could be applied during growth to dope the semiconductor, and that it may have to be accounted for during the currently used solid state doping routes. It is concluded that alkali gas-phase transport occurs through a plurality of routes and cannot be attributed to one single source.Control of alkali doping is crucial for a range of technologically relevant chalcogenide materials, from photovoltaics (CdTe, Cu(In,Ga)Se 2 , Cu 2 ZnSn(S,Se) 4 ) 1-5 and thermoelectricity (Pb(S,Se,Te)) 6-9 potentially to superconductivity (KFeSe 2 ) 10,11 and quantum computing (Bi 2 Te 3 12 , MoS 2 and WSe 2 13 ). In the case of Cu(In,Ga)Se 2 (CIGSe) solar cell material, the current alkali metal doping procedures are overwhelmingly based on condensed state reactions. Two common approaches are taken. Either by indirect control of the diffusion from a sodium-containing substrate or back contact [14][15][16][17] , or by deliberate doping from the precursor surface through a post deposition treatment (PDT), e.g. by NaF or KF evaporation onto the surface of the absorber to form a tens of nanometer thick layer, followed by annealing [18][19][20] . Control of the sodium content in the former case is difficult as substrates are never identical 21 , and in the latter case at least one extra step is required to add the alkali metal. The subject has been extensively reviewed by Salomé et al. 22. CIGSe thin films are always grown in a controlled atmosphere containing a certain pressure of selenium. The semiconductor requires selenium for its formation and to prevent its decomposition, given that the reaction is ruled by a solid/gas-phase equilibrium 23,24 . The question arises, are any other gas-phase chemical species involved in the equilibrium? All the main binary compounds of CIGSe have low vapour pressures; however, usually CIGSe contains also a considerable amount of sodium incorporated in the film. Is the vapour pressure of sodium or its

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