In this work, centimeter-scale macrocrystals of nonpolar colloidal quantum dots (QDs) incorporated into anthracene were grown for the first time. The exciton transfer from the anthracene host to acceptor QDs was systematically investigated, and anisotropic emission from the isotropic QDs in the anthracene macrocrystals was discovered. Results showed a decreasing photoluminescence lifetime of the donor anthracene, indicating a strengthening energy transfer with increasing QD concentration in the macrocrystals. With the anisotropy study, QDs inside the anthracene host acquired a polarization ratio of ~1.5 at 0° collection angle, and this increases to ~2.5 at the collection angle of 60°. A proof-of-concept application of these excitonic macrocrystals as tunable color converters on light-emitting diodes was also demonstrated.
Keywords: colloidal quantum dots; light-emitting diodes; nonradiative energy transfer; optical anisotropy; organic semiconductor macrocrystals.