High-Efficiency Blue-Emission Crystalline Organic Light-Emitting Diodes by Engineering Thermally Activated Delayed Fluorescence Nanoaggregates

A crystalline host matrix (CHM) with embedded nanoaggregates (NA) is a powerful strategy to develop high-performance crystalline OLEDs that can combine the advantages of both crystalline and high-exciton-utilization-efficiency light emitting materials. Here a CHM-NA structure blue-emission crystalline OLED is developed, which employs a thermally activated delayed fluorescence (TADF) material. The CHM-TADFNA OLED is proved to efficiently manage exciton distribution by engineering nanoaggregates. The device exhibits a remarkable EQE up to 10.4% and achieves the characteristics of rapid turn-on, and fast ramping of luminance and current density, resulting in an enhanced photon output and a lower series-resistance Joule-heat loss ratio, indicating a competitive pathway to future blue-emission OLEDs. By employing a crystalline host matrix with an embedded thermally active delayed fluorescence nanoaggregates structure, an efficient crystalline thin-film blue-emission organic light-emitting diode with high photon output and low driving voltage is created.image