Engineers at the university of California, Berkeley, and Lawrence Berkeley national laboratory have discovered a simple new process for repairing common defects in thin films. The discovery could boost the development of atomic-scale single-layer semiconductors for transparent LED screens, high-efficiency solar cells and tiny transistors. By treating a single layer of semiconductor made from molybdenum disulfide with a super-strong organic acid, the researchers were able to increase the material's efficiency a hundredfold. Lead researcher Ali Javey, a professor at the university of California, Berkeley, said: 'this study is the first demonstration of a 'perfect monolayer' of optoelectronic materials that we've never heard of being so thin.
Pictured above is a laser-excited single-layer semiconductor of imperfection molybdenum disulfide (MoS2), which has helped develop transparent LED displays, ultra-efficient solar panels, photodetectors, and nanoscale transistors.
The researchers created a layer of molybdenum disulfide just 7/10 nanometers thick, thinner than human DNA 2.5 nanometers in diameter. Impregnating the material with superacid removes contaminants and fills in missing atoms to repair defects -- a chemical reaction known as protonation
The industry's interest in single-layer semiconductors stems from their low absorption of light and their ability to withstand torsion caused by bending and other pressures. This makes it ideal for transparent or flexible devices, such as high-performance deformable LED displays and devices that can turn transparent when power is cut off.
Left - MoS2 single-layer semiconductor in the shape of Cal Logo; Image right - superacid treatment.
The process also improves transistor performance by removing defects, which have become a major impediment to computer development as chips become smaller and thinner.
'The development of a defect-free monolayer could also eliminate many of the problems encountered in developing new types of low-power switchers,' Javey said. The team's work has been published in a recent issue of the journal Science