A new chemical route to Cu2ZnSn(SxSe1‐x)4 based thin film solar cells has been developed using spin coating of commercially available molecular precursors from an environmentally friendly non‐toxic solvent. 4.1% efficiency solar cells were achieved after selenization of Cu2ZnSnS4. This technique could provide simple, facile, and reproducible fabrication for efficient and large area solar cells.

A unique type of inorganic-organic hybrid semiconductor bulk material is capable of emitting direct white light. Their photoluminescence properties can be tuned precisely and systematically by modifying structures and composition. They could be used as a single-material light-emitting source in high efficiency white-light-emitting diodes.

A unique family of II−VI based nanostructured inorganic−organic hybrid semiconductors exhibit nearly zero uniaxial thermal expansion in the temperature range of 95−295 K. Both their optoelectronic and thermal expansion properties are systematically tunable. The diamine molecules show a strong negative thermal expansion effect, and the extent of such an effect increases as the length of the organic molecules increases.

Printed on paper containing at least 50% wastepaper, including 10% post consumer waste.However the lengthy thermal process used in that tool is not viewed as a commercially scalable process, primarily due to its extended process time. Therefore the effort to use an RTP process was launched at the beginning of the project in order to develop a faster absorber formation process for eventual transfer to Solexant's pilot process line. Characterization ToolsSolexant has an array of analytical tools in-house that were used extensively throughout this project effort. These tools include scanning electron microscopy (SEM), transmission electron microscopy (TEM), electron beam induced current (EBIC), electron dispersive spectroscopy (EDS), white-light interferometry, Infrared Thermography, optical absorption spectroscopy, xray fluorescence (XRF), capacitance-voltage (C-V), current-voltage (I-V) and light-biased quantum efficiency (QE). We had collaborative efforts with NREL's Measurement and Characterization group for lock-in Infrared Thermography, SEM, focused ion beam (FIB)-SEM and EDS, STEM, EBIC, cathodoluminescence (CL) and Raman.

A group of copper iodide based hybrid semiconductors with the general formula of 2D-CuI(L) 0.5 (L = organic ligands) are synthesized and structurally characterized.All compounds are two-dimensional (2D) networks made of one-dimensional (1D) copper iodide staircase chains that are interconnected by bidentate Nitrogen containing ligands. Results from optical absorption and emission experiments and density functional theory (DFT) calculations reveal that their photoluminescence (PL) can be systematically tuned by adjusting the lowest unoccupied molecular orbital (LUMO) energies of the organic ligands. Charge carrier transport measurements were carried out for the first time on single crystals of selected 2D-CuI(L) 0.5 structures and the results show that they possess ptype conductivity with a Hall mobility of ~ 1 cm 2 V -1 s -1 for 2D-CuI(pm) 0.5 and 0.13 cm 2 V -1 s -1 for 2D-CuI(pz) 0.5 , respectively. These values are comparable to or higher than the mobilities of typical highly luminescent organic semiconductors. This work suggests that robust, high-dimensional copper iodide hybrid semiconductors are promising candidates to be considered as a new type of emissive layers for LED devices.

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Cobalt nanoparticles were synthesized on silica thin films by heat treating Co/silica films spun on thermally oxidized Si substrates. The as-deposited films were calcined in vacuum (∼0.03 Torr) for 2 h at 500 °C, followed by reduction in hydrogen at 650 °C for up to 15 h. The reduction process is characterized as one of time-dependent evolution of nanoparticles in both physical appearance and phase nature, eventually leading to the formation of well-dispersed Co nanoparticles, as ascertained by x-ray photoelectron spectroscopy and scanning electron microscopy. Slow conversion of Co ions into metallic Co observed in this study is ascribed to the absence of a Co3O4 phase that forms predominantly during calcination in air. Atomic force microscopy revealed a marked increase in the surface roughness of the film due to the development of nanoparticles. A distinct duplex-layer structure was observed in the reduced film, which consisted of the upper layer laden with nanoparticles and the lower layer essentially particle-free. The growth of the upper layer appears to be controlled by the upward diffusion of Co2+ in the film during the reduction process.

A new soluble synthetic route was developed to fabricate thin films of layered structure transition metal dichalcogendies, MoS2 and WS2. High-quality thin films of the dichalcogenides were prepared using new soluble precursors, (CH3NH3)2MS4 (M = Mo, W). The precursors were dissolved in organic solvents and spun onto substrates via both single- and multistep spin coating procedures. The thin films were formed by the thermal decomposition of the coatings under inert atmosphere. Structural, electrical, optical absorption, thermal, and transport properties of the thin films were characterized. Surface morphology of the films was analyzed by atomic force microscopy and scanning electron microscopy. Highly conductive and textured n-type MoS2 films were obtained. The measured room temperature conductivity ∼50 Ω−1 cm−1 is substantially higher than the previously reported values. The n-type WS2 films were prepared for the first time using solution-processed deposition. WS2 displays a conductivity of ∼6.7 Ω−1 cm−1 at room temperature.