GeS Nanotechnologies To Make Solar Energy Cheaper

Scientists have found a simple way to control the structure of semiconductor material germanium monosulfide, paving the way for applications in solar energy conversion and faster computer circuits.

AsianScientist (Apr. 8, 2014) – Researchers in China have found a convenient way to selectively prepare germanium sulfide nanostructures, including nanosheets and nanowires, that are more active than their bulk counterparts. This could open the way to lower cost and safer optoelectronics, solar energy conversion and faster computer circuitry.

Germanium monosulfide (GeS) is emerging as one of the most important semiconductor materials with potential in opto-electronics applications for telecommunications and computing, as well as solar energy conversion. One important property is its much lower toxicity and environmental impact when compared to other semiconductors made with cadmium, lead and mercury. It is also less costly than other materials made with rare and noble metal elements.

Glassy GeS has been used in lasers, fiber optic devices and infrared lenses, as well as rewritable optical discs and non-volatile memory devices for several years. It is also used extensively as a solid electrolyte in conductive bridging random access memory (RAM) devices.

The repertoire of this material might be extended even further with the extra control over its nanostructure. Shi Liang and Dai Yumei of the University of Science and Technology of China used simple “wet” chemistry to synthesize GeS nanostructures. The ingredients were mixed in a sealed reaction flask, blasted with ultrasound to exclude air and then stirred and heated.

The researchers found that they were able to make nanosheets of GeS this way if the process was carried out for several hours at 593 Kelvin. At a higher temperature of 613 Kelvin, the sheets wound up into nanowires. Indeed, the precise heating time and temperature allowed them to control the structure of the final product. The team suggests that nanowire formation is driven by surface tension between the sheet and OLA molecules during heating.

Having established the structural integrity of their GeS nanowires and nanosheets, the team went on to build several test devices, including a photoresponsive unit which demonstrated “outstanding photoresponsive behavior.”

“This indicates the potential use of GeS nanosheets and nanowires in solar energy conversion systems, such as the fabrication of photovoltaic devices,” said the authors.

The article can be found at: Shi and Dai. (2014) Synthesis, Formation Mechanism and Photoelectric Properties of GeS Nanosheets and Nanowires.


Source: International Union of Crystallography.

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