Vera Lebedeva | Searcharxiv

arXiv2016

From dots to stripes to sheets - Shape control of lead sulfide nanostructures

Controlling anisotropy in nanostructures is a challenging but rewarding task since confinement in one or more dimensions influences the physical and chemical properties of the items decisively. In particular, semiconducting nanostructures can be tailored to gain optimized properties to work as transistors or absorber material in solar cells. We demonstrate that the shape of colloidal lead sulfide nanostructures can be tuned from spheres to stripes to sheets by means of the precursor concentrations, the concentration of a chloroalkane co-ligand and the synthesis temperature. All final structures still possess at least one dimension in confinement. Electrical transport measurements complement the findings.

cond-mat.mtrl-sci↗

arXiv2015

Photovoltaic effect in individual asymmetrically contacted lead sulfide nanosheets

Solution-processable, two-dimensional semiconductors are promising optoelectronic materials which could find application in low-cost solar cells. Lead sulfide nanocrystals raised attention since the effective band gap can be adapted over a wide range by electronic confinement and observed multi-exciton generation promises higher efficiencies. We report on the influence of the contact metal work function on the properties of transistors based on individual two-dimensional lead sulfide nanosheets. Using palladium we observed mobilities of up to 31 cm2/Vs. Furthermore, we demonstrate that asymmetrically contacted nanosheets show photovoltaic effect and that the nanosheets' height has a decisive impact on the device performance. Nanosheets with a thickness 5.4 nm contacted with platinum and titanium show a power conversion efficiency of up to 0.94 % (EQE 75.70 %). The results underline the high hopes put on such materials.

cond-mat.mtrl-sci↗