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The employment of thermally activated delayed fluorescence (TADF) emitters is one of the most promising ways to realize the external quantum efficiency (EQE) of over 25% for organic light-emitting diodes (OLEDs). In addition, the TADF emitter based on oxygen-bridged boron (BO) fragment can maintain blue emission with high color purity. Herein, we constructed two blue TADF emitters, 3TBO and 5TBO, for OLEDs application. Both emitters consist of three donors linked at the oxygen-bridged boron acceptor. OLED devices based on 3TBO and 5TBO exhibited both high excellent device efficiency and high color purity with a maximum EQE; full-width at half-maximum (FWHM); and CIE coordinates of 17.3%, 47 nm, (0.120, 0.294), and 26.2%, 57 nm, (0.125, 0.275), respectively. [ABSTRACT FROM AUTHOR]

[Display omitted] • The HLCT property based on the ISCT emitter is presented. • The HLCT&ISCT emitter enables multi-stimulus response properties. • High efficiency and exciton utilization in OLEDs are achieved. Organic materials with multi-stimulus response (MSR) properties have magnificent application prospects in the optoelectronics field. Herein, a new asymmetric donor-spiro-acceptor type hybridized local and charge-transfer excited state (HLCT) compound based on benzothiadiazole derivative (2P-BT) moiety, Spiro-2P-BT-TPA , was designed and synthesized. The fluorene unit has a rigid linker to position the acceptor and donor subunit in close vicinity with control over their spacing and molecular structure and to achieve MSR properties, such as quasi-aggregation-induced emission (quasi-AIE), mechanochromic and solvatochromic. Moreover, Spiro-2P-BT-TPA possesses a high photoluminescence quantum yield (PLQY) of 80.9% when it is incorporated in a solid matrix, owing to spatial confined D/A stacked structure, multi-inter/intramolecular interactions as well as quasi-AIE properties. OLEDs based on Spiro-2P-BT-TPA achieve an EQE of 6.6% and the exciton utilization is 40%. To the best of our knowledge, this is a novel example for HLCT materials based on intramolecular spatial charge transfer as well as MSR properties. [ABSTRACT FROM AUTHOR]

• Two asymmetric ACZ-containing molecules ACZ-TAD/ACZ-TPA as efficient HTMs for PeSCs. • Both the HTMs exhibited low cost, high thermal stability and superior hole mobility. • The ACZ-TAD based PSCs achieved a high PCE over 20% with negligible hysteresis. • The novel HTMs delivered excellent hydrophobicity and long-term stability. Here, the asymmetrical 8,8-dimethyl-8H-indolo[3,2,1-de]acridine (ACZ) is firstly developed as central core for hole-transporting materials (HTMs) in perovskite solar cells (PeSCs). Two asymmetrical HTMs N3,N3,N6,N6,N10,N10-hexakis(4-methoxyphenyl)-8,8-dimethyl-8H-indolo[3,2,1-de]acridine-3,6,10-triamine (ACZ-TAD) and 4,4′,4′'-(8,8-dimethyl-8H-indolo[3,2,1-de]acridine-3,6,10-triyl)tris(N,N-bis(4-methoxyphenyl) aniline) (ACZ-TPA) with different arylamines branches were designed and synthesized. This molecular design for incorporating different blocks could consolidate their merits to construct new HTMs. Meanwhile, the rigid and planar ACZ fragment results in good thermal stability, high hole mobility and suitable energy level of the materials. As a result, ACZ-TAD exhibits higher hole mobility and better charge extraction property compared with ACZ-TPA and the classical 2,2′,7,7′-tetrakis-(N,N-di-paramethoxyphenylamine)-9,9′-spirobifluorene (spiro-OMeTAD). The high power conversion efficiencies (PCEs) of 18.72% and 20.23% are generated for ACZ-TPA and ACZ-TAD in the PeSCs device, which are both superior to spiro-OMeTAD (18.18%). Therefore, the molecular design concept in this work exhibits great potential in developing HTMs in the future. [ABSTRACT FROM AUTHOR]