39.1: <i>Invited Paper:</i> High Performance Red and Green Phosphorescent Emitters Suitable for BT.2020 Color Gamut

Wang, Jing; Xie, Menglan; Liu, Qi; Pang, Hai; Zhang, Cuifang; Sang, Ming; Zhang, Qi; Cai, Wei; Kwong, Raymond; Xia, Sean

doi:10.1002/sdtp.15966

Cited by 2 publications

(1 citation statement)

References 9 publications

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“…Based on the device structure of Device G where ETM‐02 is used without HBL, we fabricated a series of new devices. In this part of the work, we changed to a deep red phosphorescent emitter (DRD) as previously reported in, 19 which targets BT.2020 chromaticity. This modification comes from the increasing interest in the deep red OLEDs both in lighting and display applications 20–22 .…”

Section: Experiments and Resultsmentioning

confidence: 99%

Charge balance in OLEDs: Optimization of hole injection layer using novel p‐dopants

Xie,

Pang,

Wang

et al. 2024

J Soc Info Display

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Charge balance is one of the most important factors for realizing high performance organic light emitting devices (OLEDs). In this work, we provide a novel strategy to improve the charge balance in OLEDs by optimizing the hole injection layer (HIL) as well as the electron transporting layer (ETL) and thereby controlling the charge carrier supplies in the device. First, we develop a p‐dopant material (PD02), with a lowest unoccupied molecular orbit (LUMO) of −4.63 eV, much shallower than that of the commercial material (PD01) of which the LUMO is −5.04 eV. Nevertheless, this enables us to modulate the supply of holes to the emissive layer through tuning doping concentration. We demonstrate that device performances are significantly improved by employing such a scheme. With a 23% molar doping of PD02, a bottom emission red OLED achieves an external quantum efficiency (EQE) of over 30%, an operating voltage of 3.4 V and a LT95 ~15,000 h at 10 mA/cm2, with a Digital Cinema Initiative P3 (DCI‐P3) chromaticity of CIE (X, Y) = (0.68, 0.32). Moreover, the efficiency roll‐off is suppressed up till ~3500 cd/m2, a desirable feature in display applications. The lateral conductivity of by using such HIL is also found to be much lower than that of PD01, resulting in reduced crosstalk among RGB pixels. Next, a new electron transporting material (ETM‐02) with a deep LUMO of −2.86 eV is also introduced to further optimize the charge balance. Although devices with ETM‐02 shows lower voltage and higher EQE, lifetime is compromised. In order to improve lifetime, additional fine tuning of the charge balance is essential. Finally, a second p‐dopant PD03 with a LUMO of −4.91 eV is added to the HIL to further extend the modulation flexibility in the hole injection. A double‐layer HIL consisting of 8 nm of HTM:16% PD02 and 2 nm of HTM:3% PD03, where the former is in contact with anode, is adopted in the device structure. The bottom emission deep red device achieve EQE over 30%, an operating voltage of 3.2 V and an improved LT95 ~13,000 h at 10 mA/cm2 with a BT.2020 range chromaticity of CIE (X, Y) = (0.701, 0.299). In the double HIL configuration, the introduction of PD03 provides one more parameter for tuning and therefore improves the overall device performances.

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Section: Experiments and Resultsmentioning

confidence: 99%

Charge balance in OLEDs: Optimization of hole injection layer using novel p‐dopants

Xie,

Pang,

Wang

et al. 2024

J Soc Info Display

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11.1: Invited Paper: High Performance Deep Red OLEDs Using Dual p‐dopants to Control Hole Injection

Xie¹,

Pang²,

Wang³

et al. 2023

Symp Digest of Tech Papers

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We demonstrate improved charge balance in organic light emitting devices (OLEDs) by optimizing the hole injection layer (HIL) to control the hole density through the device. Two novel p‐dopants (PDs), PD02 with a shallow lowest unoccupied molecular orbital (LUMO) at ‐4.63 eV (reported in our previous work) and PD03 with a relatively deep LUMO of ‐4.91 eV were used. A two‐layer HIL consisting of HTM:PD02 and HTM:PD03 introduces new design flexibility to improve charge balance in the light emission layer. Using 16% by mass of PD02 and 3% by mass of PD03, we achieve, (1) a bottom emission deep red device with an external quantum efficiency (EQE) of over 30% at a CIE of (0.701, 0.299), an operating voltage of 3.2 V and LT95~13, 000 h at 10 mA/cm2. In particular, the efficiency roll‐off of this device is greatly reduced, which is highly desirable in the display industry. (2) a top emission deep red device with a current efficiency (CE) of 75 cd/A at a CIE of (0.707, 0.293), an operating voltage of 3.6 V and LT95 over 15, 000 h at 10 mA/cm2. An additional benefit from this novel dual p‐doped HIL approach is its much lower lateral conductivity compared to the standard single HIL device structure, resulting in reduced lateral crosstalk between RGB pixels.

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39.1: Invited Paper: High Performance Red and Green Phosphorescent Emitters Suitable for BT.2020 Color Gamut

Cited by 2 publications

References 9 publications

Charge balance in OLEDs: Optimization of hole injection layer using novel p‐dopants

Charge balance in OLEDs: Optimization of hole injection layer using novel p‐dopants

11.1: Invited Paper: High Performance Deep Red OLEDs Using Dual p‐dopants to Control Hole Injection

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