In order to convert light into electricity efficiently and generate flexible, high-performance solar energy, researchers have been seeking new material for solar cells.
A group headed by CUI researcher Dr. Christian Klinke (Department of Chemistry, Universität Hamburg) has now successfully used lead sulfide to create two-dimensional nanocrystals of variable density and demonstrated their suitability for use in solar cells. These findings have been published in the journal Nanoscale, among other places.
Pattern of a solar cell. The bubbles above the contacts represent the positive and negative charges. Credit: UHH/ Klinke
Lead sulfide is a semiconductor which can transform light into electric currents. The research group around Dr. Christian Klinke recently succeeded in producing two-dimensional lead sulfide nanocrystals of variable thickness. The generated structures have an area of some square-micrometers and a height of two up to 20 nanometers. The structure’s small height leads to quantum effects that influence their optical and electrical properties. This means that the characteristics can be accurately adjusted to the application of purpose. The investigations revealed that an optimal thickness exists which leads to maximal efficiency in solar cells that consist of single lead sulfide nanocrystals.
Nano technology is a key technology of the 21st century. Materials with an expansion of few nanometers (the millionth part of a millimeter) have particular optical, magnetic, electric and photoelectric properties. The results can be used in efficient light-emitting diodes, solar cells, novel sensors, photo detectors, and flexible transistors, but also in biological and medical contexts.
“We could prove that the materials are highly appropriate for the usage in transistors and solar cells and that the devices’ properties depend crucially on the layer thickness of the nanocrystals”, Dr. Klinke said. These new research results that are described in detail in the journal “Nanoscale” are a significance contribution to the knowledge about the opto-electronic properties of nanostructures with fitted shapes. They provide the basis for further research on usable two-dimensional systems and their applications.
Citation:
Dogan S., Bielewicz,Th., Lebedevaa V., and Klinke Ch.
“Photovoltaic effect in individual asymmetrically contacted lead sulfide nanosheets”
Nanoscale (2015)
DOI: 10.1039/C4NR06957A