Facile Synthesis of Multicolored Stacked Quantum Dot Films for Efficient White Light Emission

Abstract

Quantum dot (QD)-based white light-emitting diodes (LEDs) or white QD-LEDs were successfully fabricated by stacking QD films of primary colors (i.e., red, green, and blue). An ultrathin ZnO film was deposited between each QD layer to facilitate the formation of a tricolor-stacked QD structure. Such stacked QD films effectively suppress the Forster resonance energy transfer between QDs and enable efficient blue light emission, unlike randomly mixed QD films of different colors. The photoluminescence (PL) spectra of various QD films were obtained to study the change in the corresponding color gamut with applied voltage. In addition, QD-LEDs were fabricated based on the PL behavior and electronic band diagrams of QDs of different colors. Maximum luminance and peak EQE of white QD-LED shows 5700 cd/m 2 and 1.1% compared to 2200 cd/m 2 and 0.3% of QD-LED with mixed QD layer. Finally, a smooth color transition and white light emission were achieved using a blue/green/red stacking sequence for the QDs, which successfully suppressed the energy transfer effect. The overall performance and brightness of the white QD-LEDs synthesized in this study can be further enhanced by developing high-performance blue QDs.

Advancements in semiconductor quantum dots: expanding frontiers in optoelectronics, analytical sensing, biomedicine, and catalysis

“…Another emerging trend of CQDs in LED applications is to produce white light-emitting diodes (WLED). Two common approaches to producing white light from CQDs stem from either mixing a set of quantum dot films of different emission colours, 114 or by the specific synthesis of nanocrystals with a wide luminescence band. 115 To achieve a broad luminescence peak, purpose trap-related emission can be stimulated via surface passivation 116 or modification 117 or nanocrystals can be doped with specific ions such as Cu + and Mn 2+ .…”