Efficient deep-blue crystalline OLEDs via hot exciton nanoaggregate sensitizing TTA emitters

Crystalline organic semiconductors exhibit high carrier mobility. Embedding high exciton-utilization emitters as nanoaggregates (NA) within a crystalline host matrix (CHM) is an effective strategy to achieve strong light emission under a low driving voltage. In this study, a hot exciton material (PyPO) was embedded as NA into a CHM. By sensitizing a TTA-based blue emitter (DPASP), we realized a CHM-HENA-TTAD OLED through sensitization engineering. The device achieved a high external quantum efficiency (EQE) of 8.16%. Benefiting from the high mobility of the CHM, the device exhibited rapid luminance rise with increasing current, significantly enhancing photon output while reducing the proportion of Joule heating. These results demonstrate the great potential of the CHM-NA structure and provide a promising design strategy CHM-HENA-TTAD for high-performance crystalline OLEDs.