Acyclic, Linear Oligo‐meta‐phenylenes as Multipotent Base Materials for Highly Efficient Single‐layer Organic Light‐emitting Devices

Abstract

Oligo‐meta‐phenylenes have been designed and synthesized as multipotent base materials of single‐layer organic light‐emitting devices. Simple molecular structures of oligo‐meta‐phenylenes composed of linear phenylene arrays benefited from the wealth of modern reactions available for biaryl couplings and were concisely synthesized in a series. Structure‐performance relationship studies with the first seven congeners revealed key features important for the multipotent materials in single‐layer devices. As a result, highly efficient phosphorescent electroluminescence was made possible in a highly simplified device architecture comprising one‐region, single‐layer configurations. Detailed investigations with hole‐only devices disclosed that the hole mobility was effectively retarded by potent materials, which should facilitate hole/electron recombination for electroluminescence.

Universal host materials for red, green and blue high-efficiency single-layer phosphorescent organic light-emitting diodes

“…During the writing of this manuscript, Isobe and coworkers have reported green SL-PhOLEDs with a higher EQE, overpassing 20%. 34 Blue phosphors are the most difficult to host and blue-emitting PhOLEDs remain the weakest link of the technology. 5,18,42,68,[80][81][82] In this work, two blue phosphors have been used: the classical sky blue emitter FIrpic (HOMO = -5.55 eV / LUMO= -2.52 eV, E T = 2.63 eV dispersed in the present hosts, Table 2) and the barely studied blue emitter FIr6 (HOMO = -5.66 eV / LUMO= -2.32 eV, E T = 2.70 eV dispersed in the present hosts, Table 2).…”

“…19 The so-called Single-Layer PhOLEDs (SL-PhOLEDs), the simplest device only made of the electrodes and the EML, have thus stimulated a strong interest for the last fifteen years. However, reaching high efficiency SL-PhOLEDs of all the colours (red, [20][21][22][23][24][25] yellow, 21,26,27 orange, 26,27 green, 21,23,26,[28][29][30][31][32][33][34] blue 23,24,33,[35][36][37] and white 38 ) is a difficult task as removing the functional organic layers of a PhOLED stack leads to a dramatic decrease of the performance. Simplifying the PhOLED technology goes also through the use of high-efficiency universal materials which can efficiently host red (R), green (G) and blue (B) phosphors.…”

Designing Host Materials for the Emissive Layer of Single‐Layer Phosphorescent Organic Light‐Emitting Diodes: Toward Simplified Organic Devices

“…Finally, the last examples of highly efficient green SL‐PhOLEDs were also reported in 2020 by Isobe and their co‐workers (D56‐D61). [ 73 ] They have designed pure hydrocarbon (PHC) hosts constructed on the association of 5 phenylene units with either a cyclic architecture as 5Me‐[5]CMP or a linear architecture as [5]LOMP x with x : 2, 4, 5, 6, or 7 (Figure 6). The linear compounds have been substituted with either one ([5]LOMP2), two ([5]LOMP4), three ([5]LOMP5), five ([5]LOMP6), or seven ([5]LOMP7) methyl substituents in order to investigate the effect of this simple chemical modification on the device performance.…”

Quinolinophenothiazine as an electron rich fragment for high efficiency RGB single-layer phosphorescent organic light-emitting diodes

“…The goal is to bridge the gap between multi-layer PhOLEDs, which are highly efficient and widely described nowadays in literature 11,[24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40] and the new generation of single-layer PhOLEDs (SL-PhOLEDs), which still presents low performance except for a few examples. 7,23,[41][42][43] Simplifying PhOLEDs will notably reduce the inherent complexity of the stack and its cost. More importantly, for the future ecological transition, simplifying electronic devices will help to reduce its environmental footprint.…”

“…Recently, great advances have been reached with very high performance host materials reported in red, green and blue SL-PhOLEDs. 7,[41][42] However, to date, there is only a very small number of high-efficiency host materials, which are compatible with red (R), green (G) and blue (B) SL-PhOLEDs. 41 As the future of SL-PhOLEDs (and more generally organic electronics) strongly relies on the use of elementary molecular fragments, we wish to report herein the use of the QPTZ building block integrated in a universal host for RGB SL-PhOLEDs.…”