The nonlocal van der Waals density functional approach is applied to calculate the binding of graphene to Ir(111). The precise agreement of the calculated mean height h = 3.41  Å of the C atoms with their mean height h = (3.38±0.04)  Å as measured by the x-ray standing wave technique provides a benchmark for the applicability of the nonlocal functional. We find bonding of graphene to Ir(111) to be due to the van der Waals interaction with an antibonding average contribution from chemical interaction. Despite its globally repulsive character, in certain areas of the large graphene moiré unit cell charge accumulation between Ir substrate and graphene C atoms is observed, signaling a weak covalent bond formation.

Secondary phases like Cu2SnS3 are major obstacles for kesterite thin film solar cell applications. We prepare Cu2SnS3 using identical annealing conditions as used for the kesterite films. By x-ray diffraction, the crystal structure of Cu2SnS3 was identified as monoclinic. Polarization-dependent Raman investigations allowed the identification of the dominant peaks at 290 cm−1 and 352 cm−1 with the main A′ symmetry vibrational modes from the monoclinic Cu2SnS3 phase. Furthermore, micro-resolved Raman investigations revealed local variations in the spectra that are attributed to a secondary phase (possibly Cu2Sn3S7). This exemplifies the abilities of micro-resolved Raman measurements in the detection of secondary phases.

Alongside with Cu 2 ZnSnS 4 and SnS, the p-type semiconductor Cu 2 SnS 3 also consists of only Earth abundant and low-cost elements and shows comparable opto-electronic properties, with respect to Cu 2 ZnSnS 4 and SnS, making it a promising candidate for photovoltaic applications of the future. In this work, the ternary compound has been produced via the annealing of an electrodeposited precursor in a sulfur and tin sulfide environment. The obtained absorber layer has been structurally investigated by X-ray diffraction and results indicate the crystal structure to be monoclinic. Its optical properties have been measured via photoluminescence, where an asymmetric peak at 0.95 eV has been found. The evaluation of the photoluminescence spectrum indicates a band gap of 0.93 eV which agrees well with the results from the external quantum efficiency. Furthermore, this semiconductor layer has been processed into a photovoltaic device with a power conversion efficiency of 0.54 %, a short circuit current of 17.1 mA/cm 2 , a open circuit voltage of 104 mV hampered by a small shunt resistance, a fill factor of 30.4 %, and a maximal external quantum efficiency of just less than 60 %. In addition, the potential of this Cu 2 SnS 3 absorber layer for photovoltaic applications is discussed.

A precursor‐annealing process based on a Cu‐rich precursor that has a maximum power conversion efficiency of 7.5% for pure selenide kesterite cells is presented. The Cu‐rich step is beneficial for the transport properties. Nanometer‐sized domains of ZnSe are found in all films.

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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.

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