A novel solution-based approach is presented to process earth-abundant Cu(2)ZnSn(S,Se)(4) absorbers using fully dissolved CZTS precursors in which each of the elemental constituents intermix on a molecular scale. This method enables the low-temperature processing of chemically clean kesterite films with excellent homogeneity. The high performance of resulting optoelectronic devices represents a chance to extend the impact of CZTS into the next chapter of thin-film solar cells.

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The hydrazine-based deposition of Cu(In,Ga)(S,Se) 2 (CIGS) thin fi lms has attracted considerable attention in recent years due to its potential for the high-throughput production of photovoltaic devices based on this absorber material. This article provides an introduction as well as presenting a complete picture of the current status of hydrazine-based CIGS solar-cell fabrication, including the three major steps of this deposition process: dissolution of the precursor materials in hydrazine, deposition of a fi lm from the resulting precursor solution, and the completion and characterization of a photovoltaic device following absorber deposition. Recent discoveries are then discussed, regarding the dissolution chemistry of the relevant precursor complexes in hydrazine, which together represent the true foundation of this processing method. Recent studies on CIGS fi lm formation are then summarized, including the control and analysis of the crystalline phase, electronic bandgap, and fi lm morphology. Finally, the latest progress in high-performance device fabrication is highlighted, with a focus on optoelectronic characterization including current-voltage, junction capacitance, and minority carrier lifetime measurements. Finally, a discussion and future outlook is provided.

We investigate the molecular species present in hydrazine CuIn(Se,S)2 precursor solutions, their interactions, and phase formation in solution processed CuIn(Se,S)2 thin films through Raman spectroscopy. The reaction between Cu2S and sulfur yields [Cu6S4]2− ions, while [In2Se4]2− ions are formed by the reaction of In2Se3 with selenium within their respective solutions. Once combined to prepare a CuIn(Se,S)2 precursor solution, these two species appear to be bridged via newly formed In−S bonds. The creation of the In−S bonds in the CuIn(Se,S)2 precursor solution provides strong evidence for the mixing of copper, indium, sulfur, and selenium at a molecular level even prior to deposition. From this configuration, relatively little atomic diffusion is required to reach the chalcopyrite structure, which enables the formation of highly uniform polycrystalline CuIn(Se,S)2 films at relatively low temperatures.

The fabrication and operation of a solution-processed vertical organic transistor are now demonstrated. The vertical structure provides a large cross section and a short channel length to counter the inherent limitations of the organic materials. The operation of a vertical organic transistor relies on a transition metal oxide layer, V2O5, to lower the carrier injection barrier at the organic/metal interface. The effect of the oxide thickness was examined to verify the role of transition metal oxide in device operation. By studying the device performance at different temperatures and in solvent environments, an operating mechanism that occurs via an ion drift and doping process was proposed. The drift direction of the dissolved Li+ ion can be controlled by altering the gate voltage bias in order to change the carrier injection barrier.

Carbon-fiber (CF)-reinforced aluminum-matrix composites were prepared by spreading fibers and squeeze casting. The interface structure of CF/Al composites was examined using high-resolution transmission electron microscopy (HRTEM) and electron spectroscopy for chemical analysis (ESCA). Aluminum carbide (Al 4 C 3 ) interfacial reaction products were observed to nucleate heterogeneously from carbon fibers and to grow toward the aluminum matrix in the form of lath-like crystals after heat treatment. The growth of aluminum carbide was anisotropic, since it was faster along the a-and b-axes of the basal plane than along the c-axis. Both the tensile strength and the elongation of composites decline with an increased duration of heat treatment. The results of ESCA revealed that approximately 1 pct of carbide enhanced interface bonding. However, increasing the content of brittle carbides to over 3 pct after heat treatment degraded the mechanical properties of composites.

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The authors demonstrate the operation of an organic single-crystal complementary circuit in the form of a simple inverter. The device is constructed from a high mobility p-type organic single-crystal transistor of tetramethylpentacene (TMPC) and a n-type single-crystal transistor of N,N′-di[2,4-difluorophenyl]-3,4,9,10-perylenetetracarboxylic diimide (PTCDI). Field-effect mobilities of up to 1.0cm2∕Vs are reported for TMPC devices, while a mobility of 0.006cm2∕Vs is reported for a n-type PTCDI single-crystal device. Considering that organic single-crystal inverters have not yet been explored, they are representative of potential candidates for use in high-performance complementary circuits.