World's Largest Sheets of Tiny Emitters Published in Top Journal
The research team of ESF-EURYI Assoc. Prof. Hilmi Volkan Demir (EEE, PHYS and UNAM) has recently demonstrated the world's largest-area nanocrystal quantum dot sheets (as large as >50 cm x 50 cm) that are flexible and stand alone. This work has been published in one of the most prestigious journals in the field of nanotechnology, Nano Letters, 12, 3986 (2012).
Semiconductor nanocrystal quantum dots (NQDs) make tiny particles with strong emissions, offering great potential with their superior optical properties. They are very promising for use in optoelectronic devices, including light-emitting diodes (LEDs). NQDs possess widely tunable optical absorption and emission properties using the quantum size effect.
Their narrow spectral emission and broadband absorption further make these tiny particles ideal for LEDs. However, to date their utilization in large-scale applications has been a scientific challenge due to the fundamental scale mismatch between "nano" and "large." The realization of large, freestanding sheets made of these nano-emitters had not previously been possible, even though they have been studied for decades.
Dr. Evren Mutlugün, who recently completed his PhD in the Department of Physics under the supervision of Prof. Demir, and his colleagues have been able to achieve high photometric quality LEDs using such stand-alone membranes of eco-friendly Cd-free nanocrystals and have studied the excitonic interactions in these NQD films. As a part of the Singapore NRF Fellowship program, the team worked together with their lab at NTU Singapore, with which Bilkent has signed a Memorandum of Understanding. The use of such flexible Cd-free quantum dot sheets holds great promise for surface-emitting light engines that would pave the way for high-end solid-state lighting.