Recently, considerable attention in the development of Cu 2 ZnSnS 4 (CZTS)-based thin-film solar cells has been given to the reduction of antisite defects via cation substitution. In this Letter, we report the substitution of copper atoms by silver, incorporated into the crystal lattice through a solution processable method. We observe an increase in open-circuit voltage (V OC ) by 50 mV and an accompanying rise in device efficiency from 4.9% to 7.2%. The incorporation of Ag is found to improve the grain size, enhance the depletion width of the pn-junction, and reduce the concentration of antisite defect states. This work demonstrates the promising role of Ag in reducing the V OC deficit of Cu-kesterite thin-film solar cells.

The development of high efficiency semi-transparent perovskite solar cells is necessary for application in integrated photovoltaics and tandem solar cells. However, perovskite's sensitivity to temperature and solvents impose a restriction on following processes, thus favouring physical vapor deposition for the transparent contacts. Protection may be necessary especially for high energy sputtering and a transparent buffer layer providing good electrode adhesion and conductivity is desired. Here we evaluate Ag and MoOx buffer layers in pursuit of high efficiency tandem solar cells. The usage of thin Ag as a buffer layer demonstrated Indium Tin Oxide (ITO) contacts that were resistant to delamination and yielded a 16.0% efficiency of semi-transparent perovskite solar cell with average transparency of 12% in visible range and > 50% in near infrared. Further application in tandem with Cu(In,Ga)Se showed an overall efficiency of 20.7% in a 4-terminal (4T) configuration exceeding the subcells individual efficiencies.

Transparent conductors and charge transport layers play a key role in the design and fabrication of efficient renewable energy and electronic devices. Over the years, Indium tin oxide (ITO), is...

A heterojunction between a layer of CZTS nanoparticles and a layer of fullerene derivatives forms a pn-junction. We have used such an inorganic-organic hybrid pn-junction device for solar cell applications. As routes to optimize device performance, interdot separation has been reduced by replacing long-chain ligands of the quantum dots with short-chain ligands and thickness of the CZTS layer has been varied. We have shown that the CZTS-fullerene interface could dissociate photogenerated excitons due to the depletion region formed at the pn-junction. From capacitance-voltage characteristics, we have determined the width of the depletion region, and compared it with the parameters of devices based on the components of the heterojunction. The results demonstrate solar cell applications based on nontoxic and earth-abundant materials.

Wet-chemically synthesized 2D transition metal sulfides (TMS) are promising materials for catalysis, batteries and optoelectronics, however a firm understanding on the chemical conditions which result in selective lateral growth has been lacking. In this work we demonstrate that Ni9S8, which is a less common nonstoichiometric form of nickel sulfide, can exhibit two-dimensional growth when halide ions are present in the reaction. We show that the introduction of halide ions reduced the rate of formation of the nickel thiolate precursor, thereby inhibiting nucleation events and slowing growth kinetics such that plate-like formation was favored. Structural characterization of the Ni9S8 nanoplates produced revealed that they were single-crystal with lateral dimensions in the range of ∼100–1000 nm and thicknesses as low as ∼4 nm (about 3 unit cells). Varying the concentration of halide ions present in the reaction allowed for the shape of the nanostructures to be continuously tuned from particle- to plate-like, thus offering a facile route to controlling their morphology. The synthetic methodology introduced was successfully extended to Cu2S despite its different growth mechanism into ultrathin plates. These findings collectively suggest the importance of halide mediated slow growth kinetics in the formation of nanoplates and may be relevant to a wide variety of TMS.