High‐efficiency thermally activated delayed fluorescence materials via a shamrock‐shaped design strategy to enable OLEDs with external quantum efficiency over 38%

Abstract

To achieve highly‐efficient organic light‐emitting diodes (OLEDs), great efforts have been devoted into constructing thermally activated delayed fluorescence (TADF) with high horizontal dipole ratios (Θ//). Here, we proposed a design strategy by integrating a rigid electron‐accepting oxygen‐bridged boron core with triple electron‐donating groups, which exhibited a “shamrock‐shape”, namely BO‐3DMAC and BO‐3DPAC. Benefiting from the rigid and large‐planar skeletons brought by shamrock‐shaped design, BO‐3DMAC and BO‐3DPAC exhibit high Θ// of 84%/70% and 93%/94% in neat/doped films, respectively, and finally furnish excellent external quantum efficiencies (EQEs) of up to 28.3% and 38.7% in 20 wt% doped OLEDs with sky‐blue emission, as well as adequate EQEs of up to 21.0% and 16.7% in nondoped OLEDs. This work unveils a promising strategy to establish high‐Θ// TADF emitters by constructing large‐planar molecular structures using shamrock‐shaped design.

Selectively Controlling the Guest–Host Contacts to Improve the Horizontal Orientation of Thermally Activated Delayed Fluorescence Emitters

“…This fully validates the effectiveness of our molecularly designed strategy, that is, suppressing or reducing the interaction between the planar TRZ acceptor and the host surface. Recently, some shamrock-shaped (or D 3 -A type) TADF emitters have been demonstrated to exhibit preferential horizontal orientations. ,,− We note that the design strategy of those TADF emitters is similar to our case. However, a mechanistic understanding at the atomic level for this strategy is still lacking.…”

Pyrene-Based Deep-Blue Fluorophores with Narrow-Band Emission

“…This is attributed to their diverse molecular types, controllable molecular functionalization with tunable optical properties, and relatively low cost. 1,2 The photophysical properties of organic luminescent materials have played a crucial role in influencing the performance of optoelectronic devices. With the development of display technology, ultrahigh-definition displays are becoming a hot research topic and one of the most important next-generation display technologies.…”

“…Organic luminescent materials, as the key components in organic light-emitting diode (OLED) devices, have garnered significant interest in both academic research and industrial communities. This is attributed to their diverse molecular types, controllable molecular functionalization with tunable optical properties, and relatively low cost. , The photophysical properties of organic luminescent materials have played a crucial role in influencing the performance of optoelectronic devices. With the development of display technology, ultrahigh-definition displays are becoming a hot research topic and one of the most important next-generation display technologies. − Among them, the color purity of organic luminescent materials is one of the main factors that affect the ultrahigh-definition displays .…”

Disorder‐Enhanced Charge‐Transfer‐Mediated Room‐Temperature Phosphorescence in Polymer Media

“…[1][2][3][4][5][6][7] Being less expensive, more flexible and stable to moisture compared to their organometallic counterparts, these materials have found applications in various technologies such as anticounterfeiting, [8][9][10][11] encryption, [12][13] bioimaging [14][15][16][17][18][19] and optoelectronics. [20][21][22] According to the first-order perturbation theory, the rate of intersystem crossing (ISC), the first step for RTP, is proportional to the spin-orbit coupling (SOC) matrix element and the reciprocal of energy gap between the excited singlet and triplet states ( ~EST ). [23][24] A conventional way for enhancing the triplet-excited state population and achieving efficient RTP in metal-free organic luminophore is to incorporate halogen atoms (such as iodine) to augment SOC.…”