Exciton-triggered luminance degradation of organic light-emitting diodes

Ingram, Grayson L.; Zhao, Yongbiao; Lu, Zheng‐Hong

doi:10.1016/j.orgel.2019.03.023

Cited by 10 publications

(2 citation statements)

References 25 publications

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“…Intensitas cahaya dan kuat penerangan cahaya buatan stabil tanpa dipengaruhi perubahan waktu dan cuaca. Besarnya juga dapat diukur sesuai kebutuhan (Hartati et al, 2011;Ingram et al, 2019).…”

Section: Pendahuluanunclassified

Tingkat Akurasi Aplikasi Smart Lux Meter Sebagai Solusi Percobaan Mandiri Pada Pembelajaran Jarak Jauh

Marpaung

Mulyaningsih

SAPUNDANI³

2022

JPF Unimed

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Hingga tulisan ini disusun, pandemi COVID-19 masih terus berlangsung, sementara proses pembelajaran harus terus berjalan, termasuk juga praktikum. Oleh karena itu, penelitian ini bertujuan untuk mengukur tingkat akurasi percobaan yang dilakukan secara mandiri dengan studi kasus pada pengukuran kuat terang cahaya. Metode yang digunakan yaitu melakukan pengukuran terhadap 2 sumber cahaya yaitu lilin dan senter handphone yang dilakukan pada variasi jarak 15 cm, 30 cm dan 45 cm, dengan menggunakan aplikasi smart lux meter. Hasil penelitian dibandingkan dengan rumus kuat penerangan yang sudah standar. Hasil penelitian menunjukkan bahwa percobaan yang dilakukan secara mandiri, dengan menggunakan aplikasi yang ada pada smartphone, mempunyai tingkat akurasi yang tinggi, dengan nilai akurasi pengukuran kuat terang cahaya lilin dan cahaya senter handphone masing-masing sebesar 84,05% dan 83,32%. Oleh karena itu, dapat disimpulkan bahwa percobaan yang dilakukan secara mandiri dengan menggunakan aplikasi smart lux meter mempunyai tingkat akurasi yang tinggi dan dapat digunakan sebagai solusi untuk kegiatan praktikum selama pembelajaran jarak jauh.

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Section: Pendahuluanunclassified

Tingkat Akurasi Aplikasi Smart Lux Meter Sebagai Solusi Percobaan Mandiri Pada Pembelajaran Jarak Jauh

Marpaung

Mulyaningsih

SAPUNDANI³

2022

JPF Unimed

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“…Though the formation of excitons is necessary for EL, the additional energy that molecules possess while in an excitonic state can drive various unimolecular and bimolecular processes that can bring about degradative changes in the materials. In this regard, several exciton-induced degradation mechanisms have been proposed including exciton–polaron-mitigated formation of quenching centers within the emitting layer, − and chemical decomposition of the hole transport/host materials − and/or hole and electron blocking materials. − We recently discovered that exciton stress can also lead to morphological changes in organic luminescent materials, and that the changes can be accelerated when positive polarons are also present. − This phenomenon causes a decrease in the luminescence quantum yield of the materials as well as in host-to-guest energy transfer efficiency, leading to a deterioration in OLED EL efficiency . The rate of this aggregation was found to influence device EL lifetime and to correlate with material band gap, with wider band gap materials aggregating faster.…”

Section: Introductionmentioning

confidence: 99%

Direct Observation of Exciton-Induced Molecular Aggregation in Organic Small-Molecule Electroluminescent Materials

Aziz

2019

J. Phys. Chem. C

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Recent studies have suggested that exciton stress can lead to molecular aggregation in organic luminescent materials and that the phenomenon plays a leading role in the deterioration in organic light-emitting device efficiency with time. The occurrence of this aggregation, however, has until now been only inferred from indirect experimental observations. In this work, using 2-tert-butyl-9,10-di(2-naphthyl)anthracene (TBADN) and 4,4′-bis(N-carbazolyl)-1,1′-biphenyl (CBP) as representative materials, we present direct evidence of this phenomenon. Tests show that UV irradiation causes changes in the surface roughness of TBADN films, giving direct evidence of exciton-induced morphological changes. Associated changes in photoluminescence spectral characteristics point to molecular aggregation and thus corroborate these observations. Results also show that irradiated TBADN and CBP films are more susceptible to crystallization by thermal annealing, pointing to the formation of aggregates during UV irradiation that can act as nucleation sites for crystal growth. The results provide the first direct evidence of exciton-induced morphological changes and aggregation in organic small-molecule electroluminescent materials.

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55‐2: Methods for Overcoming the Trade‐off between Efficiency and Lifetime of Organic Light‐Emitting Diodes: OLED Lifetime Simulation

Lee

Han

Song

et al. 2020

Symp Digest of Tech Papers

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Next generation OLED displays demand high energy efficiency and high resolution, but it is a hard challenge for the OLED display industry to meet the needs for high efficiency and long lifetime simultaneously. When excitons relax to their ground state a photon is emitted; however, such excited exciton states can, on occasion, quench, leading to material degradation. In order to increase efficiency, a high concentration of excitons is needed, but this leads to more quenching events between excitons and polarons and, in turn, increased material degradation. Thus, a trade-off exists between efficiency and lifetime, which can be alleviated by carefully optimizing the concentration and spatial distribution of excitons. In this paper, we introduce an OLED lifetime model, which we apply to overcome the aforementioned trade-off. In order to develop the model, we first identified the key quenching factors that dominate efficiency and lifetime degradation. Based on these factors, our model can quantitatively predict device degradation. Subsequently, we can optimize the OLED stack, in terms of layer materials and thicknesses, so as to maximize efficiency, while minimizing degradation. Consequently, we demonstrate an optimized device that exhibits a 6% higher efficiency and a 2.7 times extended lifetime relative to the reference device.

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Exciton-triggered luminance degradation of organic light-emitting diodes

Cited by 10 publications

References 25 publications

Tingkat Akurasi Aplikasi Smart Lux Meter Sebagai Solusi Percobaan Mandiri Pada Pembelajaran Jarak Jauh

Tingkat Akurasi Aplikasi Smart Lux Meter Sebagai Solusi Percobaan Mandiri Pada Pembelajaran Jarak Jauh

Direct Observation of Exciton-Induced Molecular Aggregation in Organic Small-Molecule Electroluminescent Materials

55‐2: Methods for Overcoming the Trade‐off between Efficiency and Lifetime of Organic Light‐Emitting Diodes: OLED Lifetime Simulation

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