“…3 and the data are summarized in Table 3. The data indicate that the turn-on voltage is around 4 V for all the devices, which is lower than most of the printed OLEDs reported in literatures 7,8,14,16 .Figure 3( a , d ) V-J-L curves, ( b , e ) J-EQE curves, and ( c , f ) J-CE-PE curves of Device A-I.…”
Section: Resultsmentioning
confidence: 68%
“…Within the solution process, inkjet-printed devices are usually worse than the spin-coated devices 7–9 . As a result, the most of reported OLEDs by inkjet printing are a single printing layer structure, either hole transporting layer (HTL) 10–16 or emission layer (EML) 17–20 , because bilayer printed OLEDs always show inferior performance 17–19 . Conventional thermal evaporation process has been using blended host materials (co-evaporation of multi-materials) for OLEDs to achieve balanced carrier transport 20,21 .…”
In order to solve the interface issues in solution deposition of multilayer OLED devices, a blended host concept was developed and applied to both spin-coating and inkjet printing of phosphorescent OLEDs. The blended host consists of 1,3-bis(carbazolyl)benzene (mCP) and1,3,5-tri(phenyl-2-benzimidazoly)-benzene (TPBi). Maximum current efficiency (CE) of 24.2 cd A
−1
and external quantum efficiency (EQE) of 7.0% have been achieved for spin-coated device. Maximum CE and EQE of 23.0 cd A
−1
and 6.7% have been achieved for inkjet printed device. The films deposited by printing and spin-casting were further researched to explore the effect of those different processing methods on device performance.
“…3 and the data are summarized in Table 3. The data indicate that the turn-on voltage is around 4 V for all the devices, which is lower than most of the printed OLEDs reported in literatures 7,8,14,16 .Figure 3( a , d ) V-J-L curves, ( b , e ) J-EQE curves, and ( c , f ) J-CE-PE curves of Device A-I.…”
Section: Resultsmentioning
confidence: 68%
“…Within the solution process, inkjet-printed devices are usually worse than the spin-coated devices 7–9 . As a result, the most of reported OLEDs by inkjet printing are a single printing layer structure, either hole transporting layer (HTL) 10–16 or emission layer (EML) 17–20 , because bilayer printed OLEDs always show inferior performance 17–19 . Conventional thermal evaporation process has been using blended host materials (co-evaporation of multi-materials) for OLEDs to achieve balanced carrier transport 20,21 .…”
In order to solve the interface issues in solution deposition of multilayer OLED devices, a blended host concept was developed and applied to both spin-coating and inkjet printing of phosphorescent OLEDs. The blended host consists of 1,3-bis(carbazolyl)benzene (mCP) and1,3,5-tri(phenyl-2-benzimidazoly)-benzene (TPBi). Maximum current efficiency (CE) of 24.2 cd A
−1
and external quantum efficiency (EQE) of 7.0% have been achieved for spin-coated device. Maximum CE and EQE of 23.0 cd A
−1
and 6.7% have been achieved for inkjet printed device. The films deposited by printing and spin-casting were further researched to explore the effect of those different processing methods on device performance.
“…Tekoglu et al [18] also produced gravure-printed OLEDs consisting of PEDOT:PSS and a green small molecule emitter, resulting in a maximum efficiency of 7.7 cd A −1 . Inkjet printing as a deposition technique for a variety of layers of OLEDs including HIL [19], EML [20], and EIL [21] has been extensively studied. In recent years, the focus has shifted to the deposition of thermally activated delayed fluorescence (TADF) emitters for display applications.…”
Section: State Of the Art Of Printed Multilayer Oledsmentioning
confidence: 99%
“…If individual nozzles clog during printing, this can lead to perforated layers, resulting in a failure of the devices. For low viscosity values, for example when pure toluene is used as solvent, the controlled drop ejection is difficult, resulting in misdirected and irregular jets and, thus, misplaced structures or saw tooth-like edges [19]. Olivier et al [19] used solvents of a higher viscosity such as anisole and isopropanol in addition to toluene to adjust the rheological behavior of a small molecule ink.…”
In this study, multilayer organic light-emitting diodes (OLEDs) consisting of three solution-processed layers are fabricated using slot die coating, gravure printing, and inkjet printing, techniques that are commonly used in the industry. Different technique combinations are investigated to successively deposit a hole injection layer (poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS)), a cross-linkable hole transport layer (N,N′-bis(4-(6-((3-ethyloxetan-3-yl)methoxy)-hexyloxy)phenyl)-N,N′-bis(4-methoxyphenyl)biphenyl-4,4′-diamin (QUPD)), and a green emissive layer (TSG-M) on top of each other. In order to compare the application techniques, the ink formulations have to be adapted to the respective process requirements. First, the influence of the application technique on the layer homogeneity of the different materials is investigated. Large area thickness measurements of the layers based on imaging color reflectometry (ICR) are used to compare the application techniques regarding the layer homogeneity and reproducible film thickness. The total stack thickness of all solution-processed layers of 32 OLEDs could be reproduced homogeneously in a process window of 30 nm for the technique combination of slot die coating and inkjet printing. The best efficiency of 13.3 cd A−1 is reached for a process combination of slot die coating and gravure printing. In order to enable a statistically significant evaluation, in total, 96 OLEDs were analyzed and the corresponding 288 layers were measured successively to determine the influence of layer homogeneity on device performance.
“…Only a few studies use a solution process to fabricate the top-emitting OLEDs and in most of them, only one or two films are actually solution-processed. 23,[32][33][34][35][36][37] The main issue in the fabrication of solution-processed organic devices is the uniform deposition of materials on top of the active layer in an OPV device (or the emissive layer in an OLED device). Most of the active (or emissive) layers show hydrophobic properties while the materials deposited on top are in aqueous solutions.…”
Roll-to-roll (R2R) printing and coating techniques can be the answer to a low cost and large-area mass production for organic electronics devices. While the research in the photovoltaic field has...
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