A spiro-configured ambipolar host material for impressively efficient single-layer green electrophosphorescent devices

Abstract

A spiro-configured bipolar molecule (CSC) that possesses high triplet energy, suitable energy levels, and balanced ambipolar carrier mobilities was successfully applied as an efficient host material, compatible with various iridium-based green phosphors, to realize highly efficient single-layer PhOLEDs of a maximum external quantum efficiency up to 8.3% (31.4 cd A(-1)) at a practical brightness of 1000 cd m(-2) (8 V).

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

“…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.…”

Bipolar Host Materials: A Chemical Approach for Highly Efficient Electrophosphorescent Devices

“…The low triplet energy of D2ACN can be attributed to the CN‐capped ET block and diphenylamino‐terminated biphenyl HT moiety. Thus, replacing DPA in the HT block of D2ACN with carbazole and reducing the conjugation length of the ET block with a bipyridine gives a new spirobridged bipolar host host material CSC ( 104 ) 103. The orthogonal molecular configuration of CSC gives enhanced thermal ( T d = 416 °C) and morphological ( T g = 179 °C) stabilities.…”

Blue phosphorescent organic light-emitting devices based on carbazole/thioxanthene-S,S-dioxide with a high glass transition temperature

“…17 Unique molecular designs are required to develop high-E T host materials with bipolar transport properties. 18,19 Rigid building blocks with high E T 's, such as fluorenes, 20,21 arylsilane, 22,23 arylphosphine oxides, 24,25 triazines, 26 arylsilanes, 15 spirofluorenes, 27,28 and phosphazenes, 29 have been the extensively investigated on PHOLED host materials with lower HOMO or higher LUMO levels to improve their efficiencies. Recently, nonconjugated rigid building blocks, such as fluorenes, arylsilanes, and spiro-fluorenes, have been investigated as a way to satisfy the criteria of a high E T and a high ambipolar mobility to maintain a high T g .…”

“…Recently, nonconjugated rigid building blocks, such as fluorenes, arylsilanes, and spiro-fluorenes, have been investigated as a way to satisfy the criteria of a high E T and a high ambipolar mobility to maintain a high T g . [20][21][22][23][24][25][26][27][28][29] However, this approach is still limited by inflexibility when introducing the host component between the donor and acceptor unit because of multistep synthesis processes required due for p-conjugation lengths. 30,31 In this study, a simple synthesis procedure introducing a thioxanthene-S,S-dioxide bearing a sulfone group as an electron transport moiety using two non-conjugated carbazole moieties in the 9-position of the thioxanthene-S,S-dioxide ring is described.…”