根據許多文獻報導，已知許多熱活化延遲螢光材料都有實現高效率有機發光二極體的潛力，但同時兼顧高效率和穩定生命週期一直都是科學家的挑戰。此次論文設計與合成DiphCzDBA來達到高效率以及超長元件生命週期，在參雜元件中螢光量子效率可達90%、熱裂解溫度高達476 oC、〖△E〗_ST僅有19 meV、且延遲生命週期為1.09 μs、逆系統跨越常數為7.46 × 105 s-1、同時維持高水平偶極比81%。在元件表現中可達最大外部量子效率35.2%、最大亮度為26368 cd/m2、並保持低於10%的滾降現象。在生命週期結構中，元件LT80在1000 cd/m2下可長達283小時，長元件生命週期的原因是快速RISC表現能降低激子在三重激發態的濃度，減少STA、TTA的機會；另一原因是剛性結構能提高鍵結分解的能障，在激發態中保持穩定。此外，由於分子末端的苯環官能基，可以降低分子間π–π堆疊的效應，有助於降低自我滅淬提升延遲螢光，在非參雜元件中最大外部量子效率22.2%、最大亮度為31741 cd/m2、驅動電壓僅有2.2 eV、波長為587 nm、CIE為(0.55, 0.45)。同時也合成MECzDBA、EECzDBA和iPrCzDBA，比較同樣拉、推電子基但不同橋基下分子堆疊對發光表現的影響，當橋基越壅擠，熱穩定性和水平偶極比都會大幅降低，進而影響元件表現。

Organic light-emitting diodes (OLEDs) based on thermally activated delayed fluorescence (TADF) materials are promising for the realization of highly efficient light emitters. However, it is challenging to satisfy both the high device efficiency and the long operational lifetime together. Here, a highly efficient and electrochemically stable TADF emitter DiphCzDBA is designed and synthesized. This doped emitter exhibits high photoluminescence quantum yield of 90.0 %, excellent thermal stability with decomposition temperature at 476 oC, small single-triplet energy gap of 19 meV, short delayed exciton lifetime of 1.09 μs, high rate constants of RISC(7.46 × 105 s-1) and an 81% horizontal dipole ratio in the thin film. TADF light-emitting devices fabricated with these doped emitters exhibited a maximum external quantum efficiency (EQE) and luminance of 35.2%, 26368 cd/m2 and revealed low efficiency roll-off under 10%. The operation lifetime of a DiphCzDBA-based device revealed the long LT80 of 283 h at the initial luminance of 1000 cd/m2. The long lifetime of the material is likely due to the first reason is that the faster RISC reduced triplet exciton densities and suppressed STA and TTA, and the rigid structure, sp2 hybridization, exhibited high bond dissociation energies. Moreover, the incorporation of a terminal phenyl group can weaken the intermolecular π–π stacking to provide long intermolecular distance in the non-doped device, and thus significantly suppress self-aggregation which can cause emission quenching for enhanced delayed fluorescence. Non-doped device exhibited a maximum external quantum efficiency (EQE) and luminance of 22.2%, 31741 cd/m2 and a low turn on voltage of 2.2 V. The device has a peak emission wavelength of 587 nm and colour coordinates of the Commission International de l´Eclairage (CIE) of (0.55, 0.45). In addition, MECzDBA, EECzDBA and iPrCzDBA are designed and synthesized for modifying the connected bridge between same Donor and Acceptor units to compare stacking impact. When the bridge is more bulky, the decomposition temperature and horizontal dipole ratio of molecules are much lower, which affected the performance of the device.

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