“…The contact angle of the ink on a PVK-coated surface was slightly higher than what we recorded for pristine CB (Figure 1e), confirming a slight increase in surface tension entirely inhibit the particle flow in the drying droplets, 45 which is in line with our previous observations with bis(3,5-di(9Hcarbazol-9-yl))diphenylsilane as the single host. 46 Given a root mean square (rms) value of 0.79, the inkjet-printed layer of TCTA was marginally rougher than the spin-coated layer displayed in Figure 3d (100% TCTA in 100% CB). With a change in the solvent ratio to 80:20 (Figure 5b), a small but noticeable rise in contact angle was observed, which again can be attributed to the slightly higher surface tension of CHX compared to CB (Table 1).…”
Section: Acs Applied Materials and Interfacesmentioning
confidence: 97%
“…More details regarding the related underlying principles are described elsewhere. 46 Roll-off was calculated as the decreased ratios from the maximum EQE/CE in percent. 62 Ambient device stability in terms of LT 50 at a constant current equivalent to that at the initial brightness of 1000 cd/m 2 was assessed on an OLED lifetime analyzer (M600 LAB/PMX, McScience).…”
We have investigated
the impact of the ink formulation on the properties
of an inkjet-printed small molecular mixed host in a phosphorescent
organic light-emitting diode (PhOLED). Host solubility, film roughness,
and device efficiency improved by blending tris(4-carbazoyl-9-ylphenyl)amine
(TCTA) with pyrido[3′,2′:4,5]furo[2,3-b]pyridine (3CzPFP). At a host ratio of 60:40 (TCTA/3CzPFP), the brightness
increased by 33%, the efficiency roll-off at 1000 cd/m2 dropped to well below 10%, and the luminance half-lifetime (LT50) improved by 80% in comparison to the device with a single
host (100% TCTA). When the optimized ink was deposited by inkjet printing,
a maximum external quantum efficiency of 8.9% and a current efficiency
of 28.8 cd/A were achieved at 1000 cd/m2 brightness. This
amounted to around 84% of the efficiency of a spin-cast reference
device. The obtained results provide a blueprint for designing enhanced
PhOLEDs with inkjet-printed mixed hosts.
“…The contact angle of the ink on a PVK-coated surface was slightly higher than what we recorded for pristine CB (Figure 1e), confirming a slight increase in surface tension entirely inhibit the particle flow in the drying droplets, 45 which is in line with our previous observations with bis(3,5-di(9Hcarbazol-9-yl))diphenylsilane as the single host. 46 Given a root mean square (rms) value of 0.79, the inkjet-printed layer of TCTA was marginally rougher than the spin-coated layer displayed in Figure 3d (100% TCTA in 100% CB). With a change in the solvent ratio to 80:20 (Figure 5b), a small but noticeable rise in contact angle was observed, which again can be attributed to the slightly higher surface tension of CHX compared to CB (Table 1).…”
Section: Acs Applied Materials and Interfacesmentioning
confidence: 97%
“…More details regarding the related underlying principles are described elsewhere. 46 Roll-off was calculated as the decreased ratios from the maximum EQE/CE in percent. 62 Ambient device stability in terms of LT 50 at a constant current equivalent to that at the initial brightness of 1000 cd/m 2 was assessed on an OLED lifetime analyzer (M600 LAB/PMX, McScience).…”
We have investigated
the impact of the ink formulation on the properties
of an inkjet-printed small molecular mixed host in a phosphorescent
organic light-emitting diode (PhOLED). Host solubility, film roughness,
and device efficiency improved by blending tris(4-carbazoyl-9-ylphenyl)amine
(TCTA) with pyrido[3′,2′:4,5]furo[2,3-b]pyridine (3CzPFP). At a host ratio of 60:40 (TCTA/3CzPFP), the brightness
increased by 33%, the efficiency roll-off at 1000 cd/m2 dropped to well below 10%, and the luminance half-lifetime (LT50) improved by 80% in comparison to the device with a single
host (100% TCTA). When the optimized ink was deposited by inkjet printing,
a maximum external quantum efficiency of 8.9% and a current efficiency
of 28.8 cd/A were achieved at 1000 cd/m2 brightness. This
amounted to around 84% of the efficiency of a spin-cast reference
device. The obtained results provide a blueprint for designing enhanced
PhOLEDs with inkjet-printed mixed hosts.
“…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: 67%
“…Therefore, the unbalance of charge becomes worse when the content of TPBi is enhanced. And it is worth mentioning that the Device E achieved maximum luminance of 15800 cd m −2 , which is one of best luminance in printed OLEDs 7,8,16 .…”
Section: Resultsmentioning
confidence: 95%
“…Hence, the solution processed OLEDs are not as good as thermally evaporated devices. 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 .…”
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.
The main bottleneck in inkjet printing (IJP) is a stable and jettable ink formulation. This paper discusses the ink formulation for the small molecule phosphorescent dopant/host system. The study involves the estimation of Hansen solubility parameters (HSP) to formulate inkjet‐printed ink of an iridium complex‐based phosphorescent material, bis(4‐phenylthieno[3,2‐c]pyridinato‐N,C2') (acetylacetonate) iridium(III) (PO‐01) as dopant and 4, 40‐bis (carbazol‐9‐yl) biphenyl as the host of the emissive layer. Based on dopant and host HSP analyses, toluene and methyl benzoate are chosen as ink solvents. Our ink is stable for a month and can be replicated with great accuracy. The interaction of individual drops is examined in detail since resolution or film quality is highly influenced by the drop formation and spread on a substrate. Finally, an inkjet‐printed emissive layer is demonstrated on both glass and flexible substrates. The fabricated devices exhibit the maximum current efficiency and luminance of 6.4 cd A−1 and 5781 cd m−2. A technique is also shown to print large‐area organic light‐emitting diode (OLED) devices having different patterns without patterning or pixelization of the active area of the electrodes. Up to 80 × 80 mm2 large‐area OLED tiles are made using IJP of the emissive layer.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
