It is essential to manage the alignment of the locally excited (³LE) and charge-transfer triplet (³CT) and singlet (¹CT) states of thermally activated delayed fluorescence (TADF) materials to accelerate reverse intersystem crossing (RISC) process. A series of donor-acceptor (D-A) type TADF emitters were developed by attaching acridine (DMAC) or phenoxazine (PXZ) donor at 3-site of acridin-9(10H)-one (i.e. acridone, AD) acceptor. Regardless of the donor, the lowest triplet excited states (T₁) are always dominated by the ³LE_A state with certain contribution from the ³CT state. By introducing methyl (Me) or trifluoromethyl (CF₃) at 6-site of AD acceptor, the energy levels of ¹CT, ³CT and ³LE states were tuned in different ways. When the donor is DMAC, incorporating Me on AD ring (3-DMAC-6-Me-AD) destructed the emission performance, while CF₃ (3-DMAC-6-CF₃-AD) strongly stimulated the TADF by pulling down the ¹CT state level and reducing the energy splitting ΔE_ST to almost zero. In the case of strong donor PXZ, decorating acceptor with Me (3-PXZ-6-Me-AD) did not bring extinct effect on the TADF property. In particular, 3-DMAC-6-CF₃-AD and 3-PXZ-6-Me-AD exhibited high rate constants of RISC (k_RISC) of 10⁻⁶ and of radiation (k_R) of 10⁷ S⁻¹, respectively. They achieved the maximum external quantum efficiency (EQE_max) of 21.6% and 23.3% in the doped OLEDs, and realized EQE_max of 14.7% and 17.6% with low efficiency roll-offs in non-doped devices.

必须管理热激活延迟荧光 (TADF) 材料的局部激发 ( ³ LE) 和电荷转移三重 ( ³ CT) 和单重 ( ¹ CT) 态的排列，以加速反向系统间交叉 (RISC) 过程。通过将吖啶(DMAC)或吩恶嗪(PXZ)供体连接在吖啶-9(10 H )-一(即吖啶酮，AD)受体的3位点，开发了一系列供体-受体(DA)型TADF发射体。无论供体如何，最低的三重激发态（T ₁）总是由³ LE _{A态支配，而}³ CT 态有一定的贡献。通过引入甲基（Me）或三氟甲基（CF₃）在AD受体的6个位点，^1个CT、^3个CT和^3个LE状态的能级以不同的方式调整。当供体是 DMAC 时，在 AD 环 ( 3-DMAC-6-Me-AD ) 上加入 Me 会破坏发射性能，而 CF ₃ ( 3-DMAC-6-CF ₃ -AD ) 通过拉下 TADF 强烈刺激 TADF ¹ CT 状态水平并将能量分裂 Δ E _ST降低到几乎为零。在强供体PXZ的情况下，用Me（3-PXZ-6-Me-AD）修饰受体对TADF性能没有产生消光作用。特别是3-DMAC-6-CF ₃ -AD和3-PXZ-6-Me-AD 分别表现出10 ^{-6的 RISC (} k _{RISC ) 和 10} ⁷  S ^-1的辐射 ( k _R ) 的高速率常数。他们在掺杂的 OLED 中实现了 21.6% 和 23.3%的最大外部量子效率 (EQE _max )，并在非掺杂器件中实现了 14.7% 和 17.6% 的 EQE max 和低效率滚降_。