OSE Seminars
Tailoring core/shell heterostructure of colloidal quantum dots for high performance electroluminescent devices
Presented by Dr. Jaehoon Lim, Chemistry Division, LANL
Colloidal quantum dots (QDs) with core/shell heterostructure are promising active materials for novel optoelectronic devices that demand high photoluminescence quantum yield, ultra-narrow linewidth, and extended stability under chemical/physical stress. On the basis of their promise, vigorous research has been continued over the past decade to employ colloidal QDs as light emission layer in electroluminescent devices [i.e., QD-based light emitting diodes (QD-LEDs)]. The device performance has rapidly improved, in terms of peak external quantum efficiency (EQE, ~20%) and brightness (more than 100,000 candelas/m2).
Despite such rapid advance, a depression in device performance with increasing current, so-called efficiency droop, has remained an unsolved problem in QD-LEDs. We have revealed that the nonradiative processes in QD films such as dot-to-dot energy transfer or Auger decay are behind this impediment and have explored the core/shell structure and interface structure of colloidal QDs to suppress those detrimental effects. Elaborate synthetic strategies enable us to realize novel core/shell heterostructure QDs, which suppresses Auger recombination by smoothened confinement potential and minimizes dot-to-dot energy transfer by increasing shell thickness. Applying these advanced QD emitters to QD-LEDs results in improved quantum efficiency and reduced droop behavior. This further suggests the general direction of QD material engineering which should help boosting the performance of QD-LEDs, and potentially, QD-based high-power LEDs or diode lasers.
1:00 pm, Friday, December 9, 2016
Room 101, Center for High Tech Materials
Science and Technology Park - South Campus
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