69‐1: <i>Invited Paper:</i> Trap‐dependent Electrical Characteristics of Organic Semiconductor Devices

Ko, Donghyun; Lee, Jaesang

doi:10.1002/sdtp.14047

Cited by 4 publications

(3 citation statements)

References 14 publications

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“…According to our drift‐diffusion simulation, however, the charge density of the dopant in the EML is comparable to that of the host, even though the concentration is only ≈5 vol%. [ 15 ] This is because, in general, the dopant possesses energetically more favorable states for accommodating charges compared to the host, leading to spontaneous transfer of charges from the host to the dopant. Moreover, none of the previous studies paid attention to how the defect profile affects charge and exciton dynamics in PHOLEDs and hence their lifetimes.…”

Section: Introductionmentioning

confidence: 99%

Effects of Charge Dynamics in the Emission Layer on the Operational Lifetimes of Blue Phosphorescent Organic Light‐Emitting Diodes

Yang

Nam

Kim

et al. 2022

Adv Funct Materials

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Despite more than 20 years of research, the root cause of the impractically short lifetimes of blue phosphorescent organic light-emitting diodes (PHOLEDs) has remained unclear. To overcome this, the authors investigate how the electrical properties of the emission layer (EML) of blue PHOLEDs affect degradation of the devices. It is found that a large density of dopant carriers is the dominant factor triggering triplet-polaron annihilation (TPA), which is a major defect-generation and hence lifetime-reduction mechanism. In order to reduce the generation of the TPA-induced defects to ensure long device lifetimes, the dopant carrier density should be minimized by suppressing the spontaneous charge transfer from the host to the dopant initially and by supplying sufficient charges with opposite polarity into the EML. However, there exists another critical factor that offsets the low overall density of defects against device lifetimes-that is, the non-uniform distribution of defects leading to intense exciton quenching. These two degradation factors are predetermined, and hence can be controlled, by the charge mobilities of the PHOLED EML. Given these considerations, it is demonstrated that the long-lifetime blue PHOLEDs can be realized.

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Section: Introductionmentioning

confidence: 99%

Effects of Charge Dynamics in the Emission Layer on the Operational Lifetimes of Blue Phosphorescent Organic Light‐Emitting Diodes

Yang

Nam

Kim

et al. 2022

Adv Funct Materials

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“…By comparison, D3-type device possess a better overall performance: 60% lifetime promotion, 3% EQE decline and 6% voltage rise at 10 mA/cm 2 . Usually, common layer materials are selected to modulate the drift-diffusion property for balanced electron-hole recombination profiles [6][7][8], as shown in Figure 7. In our emitting layer, the transport speed of electron is several orders of magnitude faster than that of hole.…”

Section: (C) Efficiency-lifetime Trade-off In Oled Can Be Clarified B...mentioning

confidence: 99%

P‐125: Investigation of Mechanisms to Enhance Efficiency and Lifetime of Blue Organic‐Emitting Diodes

Song

You

et al. 2022

Symp Digest of Tech Papers

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A series of bottom‐emitting Blue OLEDs with an optimal efficiency and lifetime are successfully fabricated by introducing different electrical material combinations. Distinct EQE‐Current density performance are analyzed and validated by the transient EL response, which reveal the Triplet‐Triplet Annihilation (TTA) impact differently. Overall, an efficiency‐lifetime‐trade‐off have been obtained, with 60% Lifetime promotion, 3% EQE decline and 6% voltage rise. The investigation of mechanism and experimental validation provide a method in long‐lifetime and high‐efficiency device design.

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“…In order to overcome this difficulty, we suggested the method of intentionally inserting the defects with known energetics and a controlled density in a particular position in organic devices (8). This method allows ones to obtain the one-to-one correspondence between the device performance and the property of defects, i.e., a density, a position and the energy levels of their highest occupied molecular orbital (HOMO), lowest unoccupied molecular orbital (LUMO) and their excitons.…”

mentioning

confidence: 99%

65‐1: Invited Paper: Diverse Effects of Defects on the Performance of Organic Light‐Emitting Diodes

Lee

2023

Symp Digest of Tech Papers

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Defects in organic light‐emitting diodes (OLEDs) generate the electronic states whose energy level are usually found in the energy gap of OLED materials. Hence, defects can disturb the movement of, and sometimes eliminate, the charges and excitons in OLEDs. Here, we discuss how the properties of the defects, i.e., their originating positions, energy levels and densities, affect the dynamics of the charges and excitons, thereby determining the electrical and optical performance of the comprising OLEDs.

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69‐1: Invited Paper: Trap‐dependent Electrical Characteristics of Organic Semiconductor Devices

Cited by 4 publications

References 14 publications

Effects of Charge Dynamics in the Emission Layer on the Operational Lifetimes of Blue Phosphorescent Organic Light‐Emitting Diodes

Effects of Charge Dynamics in the Emission Layer on the Operational Lifetimes of Blue Phosphorescent Organic Light‐Emitting Diodes

P‐125: Investigation of Mechanisms to Enhance Efficiency and Lifetime of Blue Organic‐Emitting Diodes

65‐1: Invited Paper: Diverse Effects of Defects on the Performance of Organic Light‐Emitting Diodes

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