Efficient Cadmium-Free Quantum Dot Light-Emitting Diodes

OPERA Solutions is capable of fabricating several types of QLED samples for evaluation. To provide our customers with reliable data, we often utilize the inverted structure.

Cadmium selenide-based quantum dots are the current standard for QD applications, which are, however, subject to the RoHS restriction. Non-toxic cadmium-free QD materials, such as indium phosphide-based QDs, are highly anticipated by industry. We propose a novel approach for an efficient cadmium-free QLEDs by inserting a thin assist layer between the exciton blocking layer and the QD emitting layer.

The TADF assist layer plays a role as an exciton energy reservoir, and the excitons are eventually transferred to the QD layer by means of Foerster resonance energy transfer, resulting in a sharp red emission. We believe that in the near future, by utilizing suitable energy reservoir materials, highly efficient red and green cadmium-free QLEDs will be available, which will also pave the way for a stable cadmium-free blue QLED.

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SID Digest of Technical Papers 51, 870-873 (2020)