Charge-transfer (CT) complexes, formed by electron transfer from a donor to an acceptor, play a crucial role in organic semiconductors. Excited-state CT complexes, termed exciplexes, harness both singlet and triplet excitons for light emission, and are thus useful for organic light-emitting diodes (OLEDs). However, present exciplex emitters often suffer from low photoluminescence quantum efficiencies (PLQEs), due to limited control over the relative orientation, electronic coupling and non-radiative recombination channels of the donor and acceptor subunits. Here, we use a rigid linker to control the spacing and relative orientation of the donor and acceptor subunits, as demonstrated with a series of intramolecular exciplex emitters based on 10-phenyl-9,10-dihydroacridine and 2,4,6-triphenyl-1,3,5-triazine. Sky-blue OLEDs employing one of these emitters achieve an external quantum efficiency (EQE) of 27.4% at 67 cd m⁻² with only minor efficiency roll-off (EQE = 24.4%) at a higher luminous intensity of 1,000 cd m⁻². As a control experiment, devices using chemically and structurally related but less rigid emitters reach substantially lower EQEs. These design rules are transferrable to other donor/acceptor combinations, which will allow further tuning of emission colour and other key optoelectronic properties.

由电子从供体转移到受体形成的电荷转移（CT）配合物在有机半导体中起着至关重要的作用。激发态CT复合物（称为激基复合物）利用单重态和三重态激子来发光，因此可用于有机发光二极管（OLED）。然而，由于对供体和受体亚基的相对取向，电子耦合和非辐射复合通道的有限控制，当前的激基复合物发射体经常遭受低的光致发光量子效率（PLQE）。在这里，我们使用刚性连接子来控制供体和受体亚基的间距和相对方向，如一系列基于10-苯基-9,10-二氢ac啶和2,4,6-三苯基- 1,3,5-三嗪。^-2在1,000 cd m ^-2的较高发光强度下效率下降很小（EQE = 24.4％）。作为对照实验，使用化学和结构相关但刚性较小的发射器的设备达到的EQE大大降低。这些设计规则可以转移到其他施主/受主组合，这将允许进一​​步调整发射颜色和其他关键的光电特性。