Dimethyl acridine (Ac) and carbazole (Cz) donors are fused to produce acridine–carbazole hybrid donors 12AcCz (8,8-dimethyl-5-phenyl-8,13-dihydro-5H-indolo[2,3-c]acridine) and 23AcCz (13,13-dimethyl-7-phenyl-7,13-dihydro-5H-indolo[3,2-b]acridine).

In this work, a design approach of three thermally activated delayed fluorescence (TADF) emitters to extend the device lifetime of the TADF sensitized fluorescent devices was studied. Three TADF materials, 5‐{4,6‐bis[4‐(tert‐butyl)phenyl]‐1,3,5‐triazin‐2‐yl}‐2‐(10,15‐diphenyl‐10,15‐dihydro‐5H‐diindolo[3,2‐a:3′,2′‐c]carbazol‐5‐yl)benzonitrile (tTCNTruX), 4‐[3‐cyano‐4‐(10,15‐diphenyl‐10,15‐dihydro‐5H‐diindolo[3,2‐a:3′,2′‐c]carbazol‐5‐yl)phenyl]‐2,6‐diphenylpyrimidine‐5‐carbonitrile (PCNTruX) and 4‐(4‐{10,15‐bis[4‐(tert‐butyl)phenyl]‐10,15‐dihydro‐5H‐diindolo[3,2‐a:3′,2′‐c]carbazol‐5‐yl}‐3‐cyanophenyl)‐2,6‐diphenylpyrimidine‐5‐carbonitrile (PCNtTruX), were synthesized as sensitizers for TADF‐sensitized fluorescent organic light‐emitting diodes. The two tTCNTruX and PCNtTruX TADF emitters were designed to have Dexter energy transfer with blocking groups either in the donor or acceptor unit of the donor–acceptor‐type TADF sensitizer. The TADF materials showed small singlet–triplet energy splitting and a high reverse intersystem crossing (RISC) rate for effective sensitization of the fluorescent emission of the fluorescent emitter. tTCNTruX‐ and PCNtTruX‐sensitized fluorescent devices showed maximum external quantum efficiencies (EQEs) of 17.7 % and 11.5 % in the yellow and red devices, respectively, which were higher than those of TADF‐sensitized devices with the corresponding TADF sensitizer without a blocking group. Moreover, the device lifetime was also extended by employing the tTCNTruX and PCNtTruX sensitizers. This work demonstrated that the tTCNTruX and PCNtTruX sensitizers are effective to improve the maximum EQE and device lifetime of TADF‐sensitized fluorescent devices.

We observe how temperature and compliance currents (CCs) affect the coexistence of nonvolatile resistive memory switching (NVMS) and volatile threshold switching (VTS) in a complementary metal-oxide-semiconductor compatible Cu/SiOx/p++-Si device. NVMS and VTS behaviors are investigated at different temperatures (300 K, 360 K, and 420 K) and different CCs (100 nA–1 mA). In CCs smaller than 1 mA, NVMS and VTS coexist, and as the CC decreases, the frequency of occurrence of VTS tends to increase. The frequency of VTS events increases at higher temperatures. We demonstrate the transient characteristics of the device using a pulse transient for SET, RESET, and volatile switching. These results could be used to artificially mimic the long-term and short-term plasticity of biological synapses using the phenomena of NVMS and VTS.