Effect of Solvents, Their Mixture and Thermal Annealing  on the Performance of Solution Processed Polymer  Light-Emitting Diodes

Rezvani, Mohammad; Farajollahi, Farid; Nikfarjam, Alireza; Bakhtiarpour, Parisa; Saydanzad, Erfan

doi:10.3390/ma6051994

Cited by 16 publications

(7 citation statements)

References 35 publications

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“…Some of these issues need further investigation. In solution-processed organic devices, the solvent plays a critical role in the device performance, where the viscosity, temperature, and evaporation rate of solvent control the electrical properties of the thin film [30][31][32][33][34][35]. A non-aromatic solvent such as chloroform (CF), with a high evaporation rate, or an aromatic solvent like chlorobenzene (CB) or dichlorobenzene (DCB), with a low evaporation rate, can be employed to study device characteristics, and exploiting these properties could be an effective route to change the electrical and optical properties of the device [34].…”

Section: Introductionmentioning

confidence: 99%

Towards Highly Efficient TADF Yellow-Red OLEDs Fabricated by Solution Deposition Methods: Critical Influence of the Active Layer Morphology

Kumar

Pereira

2020

Nanomaterials

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Organic light-emitting diodes (OLEDs) based on thermally activated delayed fluorescence emitters (TADF) in simple device structures fabricated by solution processing are strongly dependent on a suitable host molecular conformation and morphology. Herein, we report the fabrication of highly efficient yellow-red TADF-based OLEDs via solution processing in a simple, two-organic-layer device structure. The devices were fabricated at different weight concentrations of 5%, 8%, and 10% emitter in an n-/p-type mixed host matrix, and their characteristics were studied. The device performance was compared with different thickness parameters for both the emitting layer (EML) and the electron transport layer (ETL) in various solvents, including chlorobenzene, dichlorobenzene, and chloroform. By optimizing the mixed ratio of EML, yellow-red OLEDs of 2-[4 (diphenylamino)phenyl]-10,10-dioxide-9H-thioxanthen-9-one (TXO-TPA) emitter in an n-/p-type host matrix of poly(N-vinylcarbazole):1,3-Bis[2-(4-tert-butylphenyl)-1,3,4-oxadiazo-5-yl]benzene (PVK:OXD-7) as a blend for the active layer were fabricated. In the best results, the device exhibited a lower turn-on voltage at around 6 V, with an external quantum efficiency (EQE) of 18.44%, current efficiency of 36.71 cd/A, and power efficiency of 14.74 Lm/W for the 8% emitter concentration. The importance of solvent for improving the electrical properties, together with organic layer thickness and host effect for the charge carrier’s transport and device characteristics are also discussed.

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Section: Introductionmentioning

confidence: 99%

Towards Highly Efficient TADF Yellow-Red OLEDs Fabricated by Solution Deposition Methods: Critical Influence of the Active Layer Morphology

Kumar

Pereira

2020

Nanomaterials

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“…Figure (10) shows the variation of optical conductivity as a function of photon energy at different annealing temperatures. The optical conductivity was calculated using equation (6).…”

Section: Volume 68mentioning

confidence: 99%

“…Thermal treatment of polymer doped laser dye after casting step of their fabrication process may improve their optical properties [10].…”

Section: Introductionmentioning

confidence: 99%

Optical Study on Deposed Polystyrene Doped DCM Laser Dye Thin Films at Different Temperature

Tuhaiwer

2016

ILCPA

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Abstract. Polystyrene (PS) polymer doped with DCM laser dye thin films have prepared on glass substrate using casting method. The obtained PS doped with DCM thin films were treated at different annealing temperatures such (30, 40, 50, 60, 70) o C. It was observed from result that the allowed direct electronic transitions energy gap was increased from 2.21 up to 2.3e.V as the temperature increasing from 30-70 o C. And the allowed indirect electronic transition energy gap rose from 0.06 to 0.15e.V as the temperature increasing. The allowed indirect phonon energy also was decreased at the same range of temperature. The different effect of temperature variation was observed on the optical properties of PS doped with DCM thin films.

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“…Semiconducting polymers are predicted to find wide use in future electronic devices because of their low cost, versatility, scalability, and solution processability. − Undoped semiconducting polymers are inherently poor electrical conductors due to their wide band gaps and low density of intrinsic charge carriers . As a result, doping is required to generate carriers and make semiconducting polymers more conductive .…”

mentioning

confidence: 99%

Crystal Structure Control of the Energetics of Chemical Doping in Rub-Aligned P3HT Films

Wu,

Duong,

Simafranca

et al. 2024

ACS Materials Lett.

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Semiconducting polymers have received increased attention in recent years as low-cost, electrically conductive layers. To show reasonable electrical conductivity, however, semiconducting polymers must be doped, a process that requires oxidation or reduction of the conjugated backbone and structural rearrangement to accommodate a charge-balancing counterion into the polymer network. Here, we aim to understand how this structural rearrangement contributes to the energetics of doping. We utilize the fact that rub-aligned poly(3hexylthiophene-2,5-diyl) (P3HT) films contain two polymorphs, one with a crystal structure that is less dense than the structure observed in unaligned films and the other with a more compact, denser structure. The two structures are dominantly face-on and edge-on with respect to the substrate, respectively, so their diffraction is well separated in q-space and thus doping induced structural changes can be monitored separately for each population. When films are doped with 2,3,5,6tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F 4 TCNQ), the less-dense face-on oriented P3HT polymorph undergoes doping induced structural change more easily than the denser edge-on oriented polymorph. This finding suggests that rearrangement of the polymer crystal structure to accommodate the dopant counterion is a significant energetic term in the doping process and that doping of semiconducting polymers can be facilitated by designing new polymers where dopant counterions can be accommodated in the polymer lattice with reduced structural change.

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Effect of Solvents, Their Mixture and Thermal Annealing on the Performance of Solution Processed Polymer Light-Emitting Diodes

Cited by 16 publications

References 35 publications

Towards Highly Efficient TADF Yellow-Red OLEDs Fabricated by Solution Deposition Methods: Critical Influence of the Active Layer Morphology

Towards Highly Efficient TADF Yellow-Red OLEDs Fabricated by Solution Deposition Methods: Critical Influence of the Active Layer Morphology

Optical Study on Deposed Polystyrene Doped DCM Laser Dye Thin Films at Different Temperature

Crystal Structure Control of the Energetics of Chemical Doping in Rub-Aligned P3HT Films

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