Phosphor-Free Three-Dimensional Hybrid White LED With High Color-Rendering Index

In this study, we demonstrate the phosphor-free hybrid white LED devices with the combination of the truncated-hexagonal-pyramid (THP) structures and quantum dots (QDs) (THPQD). In the THP structures, it is noted that the broad spectrum can be obtained from different microfacets. Moreover, the THP structures make the far-field viewing angle decrease by ∼45.4° and improve the light extraction efficiency compared with the traditional LED. The simulations also show that the light extraction efficiency of the THP LED is as approximately seven times as high as that of the traditional LED. Furthermore, by controlling the selective area growth (SAG) and adding QDs, the white emission can be realized from the THPQD LED with high color-rendering index (CRI). The CRI of the THPQD LED is from 71.2 up to 87.2 with the change of driving different current and its correlated color temperature covers the scope from 4845 to 5877 K.