High Quantum Yield Colloidal Semiconducting Nanoplatelets and High Color Purity Nanoplatelet QLED

Recently, colloidal semiconductor nanoplatelets (NPLs) have drawn attention due to their quasi-two-dimensional quantum well structure with extremely narrow photoluminescence. However, the quantum yield of NPLs reported so far is still low compared to the traditional semiconductor quantum dots. In this paper, we demonstrate a method of synthesizing CdSe/CdS core/crown NPLs with well-controlled layer thickness [four-monolayer (4-ML)] and aspect ratio, and hence efficiently enhance their photoluminescence quantum yield to ~47% and 72% for the core and core/crown NPLs, respectively. With these NPLs, we further fabricated the 4-ML NPL QLED device emitting at 516 nm with super color purity (linewidth of 10 nm), which is good enough to achieve a wide color gamut larger than Rec. 2020.