30 November 2017
Efficient 2D semiconductors herald flexible displays
Published online 1 December 2015
Researchers have developed highly efficient 2D semiconductors that can be used to make flexible or transparent displays.
A new preparation technique has improved the luminescence efficiency of 2D optoelectronic semiconductors more than a hundredfold, opening the door to futuristic screens and more efficient solar cells.
Although 2D semiconductors would be ideal for making transparent or flexible displays, poor efficiency has hampered their development. Researchers in the United States, Taiwan and Saudi Arabia have collaborated to overcome this hurdle by treating a MoS2 monolayer with an organic superacid, resulting in an opto-electronically perfect 2D semiconductor1.
“Energy in semiconductors is stored by excited particles that travel within the material and can emit light. If the semiconductor is low quality, these excited particles can lose their energy to heat at trap sites. We reduced the number of traps in MoS2 to the point where less than 5% of the excited particles become trapped before giving off light,” explains co-lead author Matin Amani of the University of California, Berkeley, USA.
The result is an increase in the photoluminescence efficiency from just 1% to over 95%.
In addition to bringing flexibility to our screens, efficient MoS2 semiconductors offer the promise of better solar cells. Semiconductors in existing solar cells become less efficient at lower intensities, thus suffering doubly at low light levels.
Since the treated MoS2 semiconductor remains efficient even at low intensities, it could be used to make solar cells which perform well even in cloudy conditions.
- Amani, M. et al. Near-unity photoluminescence quantum yield in MoS2. Science 350, 1065–1068 (2015).