Molecular Engineering Modulating the Singlet–Triplet Energy Splitting of Indolocarbazole-Based TADF Emitters Exhibiting AIE Properties for Nondoped Blue OLEDs with EQE of Nearly 20%

Strategic carbazole-cycloalkyl fused donors to induce TADF featured AIE for high efficiency deep blue emission

“…As recent blue TADF emitters with AIE nature have reported EQE max values of 19.5% by Xi using PICzPMO and 7.05% by Zhai using BCzDPM in OLEDs (Fig. S7, ESI†), 48,49 comprehending how CyCzTrz and Cy2CzTrz result in relatively low EQE max values is crucial, and the root causes of such low efficiencies of D1 and D2 can be attributed to the charge imbalance and low exciton utilization efficiency (EUE). The mobilities of the holes and electrons were calculated within the space charge limited current (SCLC) region of nondoped HODs and EODs, as shown in Fig.…”

Pyrazino[2,3-f][1,10]phenanthroline-based color-tunable thermally activated delayed fluorescence emitters with AIE characteristics for high-efficiency organic light-emitting diodes

“…These emitters have a planar acceptor segment; however, the donor segment is orthogonal to the acceptor segment which restricts direct π–π interactions, thus avoiding non-radiative pathways and turning on radiative pathways. 51,52 Restriction of π–π stacking can be achieved by incorporation of the AIE effect, 53,54 and integration of AIE and TADF into the same molecule presents a promising pathway towards achieving highly efficient OLED devices. 55–58 These molecules are expected to be emissive in the aggregate state as the AIE effect is found to be present.…”

Effects of the nature of donor substituents on the photophysical and electroluminescence properties of derivatives of perfluorobiphenyl: donor–acceptor versus donor–acceptor–donor type AIEE/TADF emitters

“…7 The reduction of energy barrier between the first singlet and first triplet excited states is generally achieved by spatial separation of the highest occupied and lowest unoccupied molecular orbitals, the HOMO and LUMO, respectively. 8,9 One of the design strategies for TADF materials is the development of donor–acceptor or donor–acceptor–donor structures, which can guarantee the formation of intramolecular charge transfer states. 10 Restriction of intramolecular rotational and vibrational motions can lead to aggregation induced emission enhancement (AIEE).…”