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In this study, we report the effects of the substrate rotational speed on the morphological characteristics of lithium fluoride (LiF) during thermal evaporation. LiF is used as a typical material in a vacuum-level shift-based electron injection layer and can improve both the charge injection and light emission properties when inserted into the electrode/organic material interface of organic light-emitting diodes (OLEDs). In general OLED research, rotary evaporation is widely used to ensure uniformity. However, there are few reports regarding the effects of this rotary evaporation method on the morphological characteristics of the thin films. Therefore, in this study, we analyzed the effects of rotary variations on the morphological and electron injection characteristics during deposition. The root mean square roughness of the LiF thin film deposited on Alq3 changed by up to 12.3%. Additionally, the driving voltage of the electron-only device showed a difference of 2.3 V at maximum and a change in the slope of the ohmic region was demonstrated. The morphological change in the LiF thin film based on the rotational speed of the substrate had a significant influence on the reaction at the electrode/organic material interface.

In the research of organic light-emitting diodes (OLEDs), the OLEDs that are fabricated via conventional doping methods have complicated structures and fabrication processes. To overcome these limitations, the ultra-thin emission layer (EML) method, which adopts a simple structure has been effectively used in the research of OLEDs. However, studies on white color OLEDs (WOLEDs) fabricated using the ultra-thin EML method are scarce. In this paper, we report the results of color tuning for the realization of WOLEDs based on an ultra-thin EML structure. The WOLEDs were fabricated and evaluated based on a two-color dopant system (sky-blue dopant and yellow dopant). The fabricated WOLEDs exhibited color coordinates of the International Commission on Illumination (CIE) 1931 from (0.287, 0.436) to (0.486, 0.483) according to the thickness ratio of the two dopants. This result suggests that the WOLEDs color tuned with multi-color dopants can be fabricated based on the ultra-thin EML method, and the development of WOLEDs with high efficiency and stability can be attained in the future.

In this study, we report the self-nanostructured growth of 4,6-bis(3,5-di(pyridin-3-yl)phenyl)-2-methylpyrimidine (B3PyMPM), which is widely used as an electron transport layer for organic light-emitting diodes (OLEDs). B3PyMPM nanostructures were formed on the surface of a substrate using vacuum thermal evaporation, and parameters such as substrate rotation speed and evaporation angle were altered to study their effect on the growth of nanostructures. Moreover, it was proven that the growth of nanostructures was dependent on the underneath materials. This self-nanostructured growth of B3PyMPM would affect the outcoupling and the efficiency improvement of OLEDs.

BackgroundCompared to the conventional approach, including preoperative orthodontic preparation, the so-called surgery-first approach (SFA) seems to reduce the overall treatment time in the correction of skeletal class III dentofacial deformity. However, there have been controversies about postoperative skeletal stability with SFA. Therefore, we investigated the long-term stability and the overall treatment time after maxillomandibular surgery for skeletal class III correction with or without preoperative orthodontic preparation.MethodsThis retrospective study included eight patients who underwent maxillomandibular surgery for class III correction with the SFA (SFA group) and 20 patients who underwent the conventional approach (CA group). A comparative study of the change in the maxillary and mandibular position on preoperative (T1), 1-day (T2), 6-month (T3), and 2-year (T4) postoperative lateral cephalograms. We calculated the overall treatment time for each group.ResultsAt the presurgical stage (T1), there was no bias in the skeletal features between the two groups. In the surgical change from T1 to T2, the mandible (point B) of the CA group was significantly moved superiorly. Short-term changes from T2 to T3 revealed that the mandible moved forward in both groups, whereas the maxillary position showed no significant changes. Long-term changes from T3 to T4 demonstrated that none of the measured parameters showed any significant differences. Finally, the average of overall treatment time was 15.1 months in the SFA group and 26.0 months in the CA group.ConclusionsThese findings suggest that SFA in bimaxillary orthognathic surgery for skeletal class III correction leads to predictable long-term skeletal stability, similar to surgery with CA. Furthermore, SFA reduced the overall treatment time compared to CA.

Background Many studies on maintaining the condyle in a normal or anatomical position during orthognathic surgery have been conducted to stabilize surgical outcomes and prevent iatrogenic temporomandibular joint complications. The aim of this study is to evaluate the changes in condylar positions after orthognathic surgery using virtual surgical planning via the balanced orthognathic surgery (BOS) system. Methods Postoperative changes in condylar position were retrospectively evaluated in 22 condyles of 11 patients with skeletal class III malocclusion who underwent orthognathic surgery using virtual surgical planning via the BOS system. The center point coordinates of the condylar head before and after orthognathic surgery were analyzed using voxel-based registration. Results Changes in the condylar position mainly occurred downward in the y-axis (−1.09 ± 0.62 mm) (P < 0.05). The change in the x-axis (0.02 ± 0.68 mm) and z-axis (0.01 ± 0.48 mm) showed no significant difference between before and after orthognathic surgery. Conclusion These results indicate that the changes in the condylar positions after orthognathic surgery using virtual surgical planning via the BOS system mainly occurred downward in the y-axis, with slight changes in the x- and z-axes. The change in the condylar position after orthognathic surgery using the BOS system is clinically acceptable.

In this study, an external light extraction layer with a micro-nano hybrid structure was applied to improve the external light extraction efficiency of organic light-emitting diodes (OLEDs). A reactive ion-etching (RIE) process, using O2 and CHF3 plasma, was performed on the surface of the micro-scale pattern to form micro-nano hybrid structures. According to the results of this study, the nanostructures formed by the treatment of O2 and CHF3 were different, and the efficiency according to the structures was analyzed experimentally and theoretically. As a result, the OLED, to which the micro-nano hybrid structure, manufactured through a simple process, is applied, improved the external light extraction efficiency by up to 38%, and an extended viewing angle profile was obtained. Additionally, an effective method for enhancing the out-coupling efficiency of OLEDs was presented by optimizing the micro-nano hybrid structure according to process conditions.

In this study, we fabricated a random nanostructure (RNS) external light extraction composite layer containing high-refractive-index nanoparticles through a simple and inexpensive solution process and a low-temperature mask-free process. We focused on varying the shape and density of the RNSs and adjusted the concentration of the high-refractive-index nanoparticles to control the optical properties. The RNSs fabricated using a low-temperature mask-free process can use the distance between the nanostructures and various forms to control the diffraction and scattering effects in the visible light wavelength range. Consequently, our film exhibited a direct transmittance of ~85% at a wavelength of 550 nm. Furthermore, when the RNSs’ composite film, manufactured using the low-temperature mask-free process, was applied to organic light-emitting diodes (OLEDs), it exhibited an external quantum efficiency improvement of 32.2% compared with the OLEDs without the RNSs. Therefore, the randomly distributed high-refractive-index nanoparticles on the polymer film can reduce the waveguide mode and total reflection at the substrate/air interface. These films can be used as a scattering layer to reduce the loss of the OLED substrate mode.

Of the drugs developed to prevent and treat osteoporosis, bisphosphonate has played a very important role in preventing osteoporotic fractures. However, case reports describing atypical femoral fractures in patients using long-term bisphosphonates have emerged. The majority of atypical femur fractures occurs in the lateral aspect of the subtrochanteric or femur diaphysis, which is explained by accumulation of tensile stress in these areas. Although the superior cortex of the femur neck withstands maximum tensile stress, to our knowledge, there have been only two reports (three cases) of atypical femoral neck fracture. In addition, none of those case reports revealed detailed pathology related to suppressed bone turnover rate. We encountered an incomplete femoral neck fracture and diagnosed it as "atypical" on the basis of the patient's lack of trauma and medication history and pathological findings. For patients with groin pain, minimal or no trauma, and a history of long-term bisphosphonate use, an atypical femoral neck fracture should be considered.

The aims of this study were to propose a minimally invasive lateral approach technique for maxillary sinus floor elevation (MSFE) with simultaneous implant placement and to evaluate the surgical outcome and complications of this technique. This study reviewed 49 surgeries of MSFE with simultaneous implant placement (n = 83) using a minimally invasive lateral approach. A circular shape window with a diameter of 5 to 6 mm and an area of 20–30 mm2 was made on the lateral wall of the maxillary sinus. After elevation of the Schneiderian membrane, the xenograft was used for bone grafting. The MSFE was possible with a minimum-sized window in 47 of 49 cases. For the remaining 2 cases, MSFE with a minimum-sized window was failed. In one case, it was expanded to be more than 30 mm2 to repair the membrane perforation. In another case, MSFE was performed by forming two minimum-sized windows. Post-operative bleeding after MSFE occurred in one anticoagulant-treated patient. There was no failed implant during the follow-up period (mean 22 months). A minimally invasive lateral approach through a small circular window with a diameter of 5 to 6 mm is a feasible and safe technique for MSFE with simultaneous implant placement.

In this study, we fabricate solution processable, flexible, and transparent hybrid electrodes. The hybrid electrodes are designed by depositing a tungsten trioxide (WO3) buffer layer on silver nanowires. The fabrication method is solution based, and the electrodes can be fabricated directly on a flexible substrate at low temperatures. This fabrication method is cost-effective and scalable. The hybrid electrodes show high flexibility, transparency, and conductivity. In addition, since the thickness of the WO3 buffer layer can be controlled, the transparency, conductivity, and surface roughness of the hybrid electrodes can be tailored. These hybrid electrodes are potential alternatives to conventional indium tin oxide electrodes for flexible electronic devices.

We investigated various characteristics of chlorinated indium tin oxide (Cl-ITO) for highly efficient organic light-emitting diodes (OLEDs): the work function, surface morphology, wetting characteristic, and hole-injection property. Via the systematic analysis of Cl-ITO, we showed that the modification of ITO using the plasma treatment method has a simple process and offers higher stability than that achieved with a solution-based modification method. We fabricated Cl-ITO with a high work function of 6.04 eV, which is 1.04 eV higher than that of pristine ITO. We verified that Cl2 plasma treatment does not affect the ITO surface morphology. The Cl halogenated surface showed a low surface polarity and influenced the growth of the organic material, especially for films as thin as ∼4 nm. Therefore, we found when using ultra-thin film on Cl-ITO for design devices, the wetting characteristic of Cl-ITO should be considered. In addition, using tris-(4-carbazoyl-9-ylphenyl)-amine resulted in increased current and power efficiencies compared with those obtained using 4,4′-N,N′-dicarbazolebiphenyl. When a carrier-only device was used, the carrier-injection characteristics of Cl-ITO were higher than those of other well-known hole-injection materials. Furthermore, the Cl-ITO OLEDs showed higher stability than OLEDs with other hole-injection materials.

A light extraction structure and a flexible electrode have been developed to enhance the electroluminescence (EL) efficiency of flexible organic light-emitting diodes (FOLEDs). However, these structures are still influenced by optical losses, poor electrical stability, and low throughput, and are not suitable to be adopted into FOLEDs due to the surface roughness problem, low flexibility/adhesion, complicated process, and high temperature/pressure process. Here, to solve these problems, we demonstrate embedded Ag nanowires (AgNWs) in flexible substrate and highly flexible random nano pattern via easy/low-cost solution form process at atmospheric pressure and low temperature without any additional material. This study demonstrates an internal and external light extraction structure composed of double-sided nano-dimpled substrate PVB (DndP), which is directly fabricated on both sides of a flexible substrate (polyvinyl butyral, PVB) only in itself without additional material via the easy/low-cost transferring process using the anodic aluminum oxide (AAO) template by an anodization process-based solution form at atmospheric pressure and low temperature. Therefore, because the DndP and the substrate are composed of the same material, PVB, there is no light loss between their interfaces. In addition, a high-refractive-index TiO2 nanoparticle, for the scattering effect, and AgNWs, for electrode flexibility, are embedded into the DndP via the covering method using the solution form. Such structures exhibit extraordinary mechanical flexibility due to the AgNWs embedded in the PVB substrate. Therefore, FOLEDs using such structures can be well adapted to flexible/rollable/foldable displays and wearable application devices. Moreover, the corrugated surface of FOLEDs by such structures can improve the current flow through increased surface area of electrodes and extract the trapped light through the scattering effect (Rayleigh, Mie), reducing the total reflection and coupled photon in metal/dielectric. In addition, the FOLEDs with such structures show color/spectrum-stable property and independence of viewing angles owing to their random nature. The final green FOLEDs with DndP, embedded scattering TiO2 nanoparticle, and embedded AgNWs&PEDOT:PSS demonstrate an outstanding EL efficiency enhancement ratio of 2.23 time via internal and external light extraction without electrical short.

We present a micro-sphere PDMS film to improve the external quantum efficiency (EQE) in OLEDs. The micro-sphere PDMS film was fabricated with the breath figure (BF) and replica molding process. The polymer template was prepared through stabilization of the water droplets at the polymer/water interface. The micro-sphere PDMS film was fabricated by pouring PDMS on the polymer template. At a 45 mg/mL concentration, the size of the spheres was approximately 12.3 µm and they had the most circular shape, so this condition yielded the best performance, with an improvement of 33% in the EQE and the widest viewing angle ranging from 0° to 50°. As a result, the sphere film’s size and distribution seem to play important roles in enhancing the EQE in OLEDs. Furthermore, the flexible sphere film based on polymeric materials could offer an effective, large-scale, mass-produced product and a simple process and approach to achieve high efficiency in flexible OLEDs.

Recently, after the first demonstration of efficient, thermally activated delayed fluorescence (TADF) organic light-emitting diodes (OLEDs), these devices have been widely investigated, and several new materials (hole and electron transport materials) have been reported. In this work, we demonstrate highly efficient TADF OLEDs with a simplified structure, and systematically characterize these partially evaluated reported materials; (4s,6s)–2,4,5,6,–tetra(9H–carbazol–9–yl)isophthalonitrile (4CzIPN) has been used as a TADF emissive dopant; the exciton blocking and carrier transport characteristics of 9,9′–Diphenyl–6–(9–phenyl–9H–carbazol–3–yl)–9H,9′H–3,3′–bicarbazole (Tris-PCz) and 2,7–bis(2,2′–bipyridin–5–yl)triphenylene (BPy-TP2) have been characterized and compared with those of other widely used well-known organic materials. The demonstrated simplified TADF OLEDs with a 4CzIPN doped single emissive layer showed a high peak external quantum efficiency and power efficiency of 18.6% and 31.5 lm/W, respectively.

In this study, we report highly efficient green phosphorescent organic light-emitting diodes (OLEDs) with ultra-thin emission layers (EMLs). We use tris[2-phenylpyridinato-C2,N]iridium(III) (Ir(ppy)3), a green phosphorescent dopant, for creating the OLEDs. Under systematic analysis, the peak external quantum efficiency (EQE) of an optimized device based on the ultra-thin EML structure is found to be approximately 24%. This result is highest EQE among ultra-thin EML OLEDs and comparable to the highest efficiency achieved by OLEDs using Ir(ppy)3 that are fabricated via conventional doping methods. Moreover, this result shows that OLEDs with ultra-thin EML structures can achieve ultra-high efficiency.

In this paper, we report on the effects of the substrate thermal evaporation process rotation speed on the electroluminescence (EL) characteristics of organic light-emitting diodes (OLEDs). In general OLED research, rotational and angle tilted deposition are widely used to maintain uniformity. However, there have been few reports on the effects of this deposition method on film characteristics. We analyzed these effects and found that the film density and its refractive index showed remarkable changes as a function of substrate rotational speed during tilted deposition. The EL characteristics of the transport layer of fluorescent OLEDs were also significantly affected. We derived the OLED optimal thickness and refractive index from our calculations.

Background Pedicled buccal fat pad (PBFP) has been used for the reconstruction of small-sized maxillary defects but cannot be used without hard tissue support on the defect larger than 4 cm × 4 cm × 3 cm. Case presentation A 64-year-old man had a history of squamous cell carcinoma of the left maxilla. After removal of the posterior maxilla, a complex bone defect (size, 5 cm × 4 cm × 3 cm) was immediately reconstructed using PBFP combined with a titanium mesh. A pinpoint fistula was found in the left palatal region 1 month after the surgery and was treated with a palatal sliding flap. There were no further complications during the follow-up. Conclusion The present technique demonstrated that PBFP combined with a titanium mesh could be used for the reconstruction of complex maxillary defect (size, 5 cm × 4 cm × 3 cm) without additional bone graft.

There is an association between diabetes and impaired bone healing. The purpose of this study was to determine whether sericin had a positive effect on bone regeneration with streptozotocin-induced diabetes in a rat model. Sprague Dawley rats (n = 21) were assigned to one of three groups. A critical-sized bone defect was created on the calvaria. In the sericin group (S group, n = 7), the bone defect was filled with a sericin–gelatin combination, whereas in the gelatin group (G group, n = 7), only gelatin sponge was used. The control group (N group, n = 7) did not receive any graft. New bone formation was evaluated by micro-computerized tomogram and histological analysis. The regenerated bone volume in group S was the highest among the three groups (3.87 ± 2.51 mm3), followed by group N (1.71 ± 1.65 mm3) and group G (1.24 ± 1.05 mm3). The application of sericin in combination with a gelatin sponge enhanced the process of bone regeneration in streptozotocin-induced type I diabetes animal model.

The viewing angle characteristics and light extraction efficiency of organic light-emitting diodes (OLEDs) with a micro-cavity structure were enhanced. This was accomplished by inserting a diffusion layer composed of nano-sized structures of a transparent polymer poly(methyl methacrylate) (PMMA) combined with a zinc oxide (ZnO) semi-planarization layer with a high refractive index (n = 2.1) into the devices. The PMMA nanostructures were fabricated by employing a reactive ion etching (RIE) process. The height and density of the PMMA nanostructures were controlled by varying the speed at which the PMMA was spin-coated onto the substrate. The insertion of the diffusion layer into the micro-cavity OLEDs (MC-OLEDs) improved the external quantum efficiency (EQE) by as much as 17% when compared to that of a MC-OLED without a diffusion layer. Furthermore, adjustment of the viewing angle from 0° to 60° halved the peak shift distance of the electroluminescence (EL) spectra from 42 to 20 nm. Additionally, changing the viewing angle from 0° to 60° changed the color coordinate movement distance of the MC-OLED with the diffusion layer to 0.078, less than half of the distance of the MC-OLED without the diffusion layer (0.165).

Conventional sensors are rigid, involve complex processes and structures, and one sensor can detect only one type of stimulus. The manufacturing costs of such devices are high owing to the use of vacuum processes for the formation of thin films and electrodes and the complicated fabrication processes required to construct multiple layers. In addition, the multiple-layer design increases the risk of peeling due to mechanical movement. In this study, to solve the aforementioned problems, a simple two-layer multi-sensor has been fabricated using a non-vacuum solution process. The sensor consists of a light absorption layer comprising polyvinyl butyral and semiconductor particles and a top layer comprising two spiral-shaped Ag nanowire electrodes. The sensor experiences minimal damage by external adhesives and has a light-sensitive optical response at 420 nm and at 1.2 mW cm−2. Herein, the capacitance of the sensor applied to the two-electrode structure was determined, along with the light sensitivity and change in noise with frequency. We believe that the proposed multi-sensor can be applied in a wide range of fields because it can act as a touch sensor and light sensor.

The phenomenon by which the efficiency decreases rapidly with the increase in luminance or current density in organic light-emitting diodes is termed efficiency roll-off. In particular, phosphorescent organic light-emitting diodes are known to have higher efficiency, but tend to exhibit higher efficiency roll-off compared with fluorescent organic light-emitting diodes. In this study, we report the efficiency roll-off characteristics of double-dopant phosphorescent organic light-emitting diodes. The double-dopant phosphorescent organic light-emitting diodes showed significantly lower efficiency roll-off compared with single-dopant phosphorescent organic light-emitting diodes. (The double-dopant device showed a 2.5-fold decrease in efficiency roll-off compared with the single-dopant device at 50 mA/cm2, and a 1.6-fold decrease in efficiency roll-off at 100 mA/cm2).

In this work, we report the effect of the rotation speed of the deposited substrate on the electroluminescence (EL) efficiency of the organic light-emitting diode (OLED). Because it has been reported that the deposition angle velocity affects the growth of an organic thin film, it is expected that the OLED EL characteristics must be affected depending on the substrate rotation velocity. Thus, in this work, the substrate rotation velocity was altered during the deposition of each organic material. The OLED devices fabricated with different depositing substrate rotation speeds showed different EL characteristics. The film thickness of the organic materials with different substrate rotation speed was carefully controlled. It was confirmed to be the same with a surface profiler and was further field enhanced using a scanning electron microscope. The difference in peak EQE was observed to be greater than 1.5 times. Based on this result, it is possible to conclude that the speed of the rotational deposition system should affect the film characteristics and therefore should be considered an important parameter.

To extract the confined waveguided light in organic light-emitting diodes (OLEDs), inserting a low refractive index (RI) periodic structure between the anode and organic layer has been widely investigated as a promising technology. However, the periodic-structure-based light extraction applied inside devices has been shown to severely distort spectrum and affect EL characteristics. In this study, a simple light extraction technology using periodic low-RI nanodot array (NDA) as internal light extraction layer has been demonstrated. The NDA was fabricated simply via laser interference lithography (LIL). The structural parameters of periodic pattern, distance, and height were easily controlled by the LIL process. From computational analysis using finite-difference time-domain (FDTD) method, the NDA with 300 nm pitch and 0.3 coverage ratio per unit cell with 60 nm height showed the highest enhancement with spectral-distortion-minimized characteristics. Through both computational and experimental systematic analysis on the structural parameters of low-RI NDA-embedded OLEDs, highly efficient OLEDs have been fabricated. Finally, as representative indicators, hexagonal and rectangular positioned NDA-embedded OLEDs showed highly improved external quantum efficiencies of 2.44 (+29.55%) and 2.77 (+57.38%), respectively. Furthermore, the disadvantage originating from the nanoscale surface roughness on the transparent conductive oxide was minimized.

Purpose The aim of this study was to evaluate the effect of buccal fat pad (BFP) in the palatoplasty and to investigate the risk factors associated with postoperative palatal fistula formation. Materials and methods Sixty-five cleft palate patients were enrolled for this study. Clinical data regarding sex, age, type of cleft, surgical technique, the ratio of cleft width, and BFP graft were collected. The ratio of cleft width was measured and calculated using preoperative clinical photographs. In 36 patients, the BFP was harvested and grafted on the cleft palate to prevent palatal fistula formation. The patients were followed up, the incidence of fistula formation was investigated, and the risk factors related with the fistula were evaluated. Results Four patients had postoperative palatal fistula and were not BFP grafted during operation. The BFP graft and ratio of cleft width are significant factors in palatal fistula formation (P = .035, .003). There was a significant difference in the ratio of cleft width between the normal and fistula groups (P = .006). In the logistic regression analysis, there was significant association between high ratio of cleft width and palatal fistula formation in the no BFP group (odds ratio; 11.15, P = .036). Conclusions The ratio of cleft width and BFP graft was a significant factor in palatal fistula formation. The BFP graft is a reliable procedure to prevent palatal fistula formation and increase the success of palatoplasty.

In this study, we evaluated a nanoscale random rubbed structure (nRRS) used as a scattering layer in organic light-emitting diodes (OLEDs) through an innovative manufacturing method. The rubbing technique, which is conventionally utilized only for liquid crystal alignment, is a manufacturing process with excellent merit in that it can form nanoscale random corrugation in a large area without vacuum equipment even at room temperature, and it is simple and inexpensive. The optimized nRRS, fabricated via rubbing, exhibited a high transmittance of 97.8% and haze of 17.8%, making it suitable as a scattering layer for OLEDs. Owing to its random nature, the scattering effect occurred effectively by rearranging the waveguided light inside the glass substrate. The OLED combined with the optimized nRRS showed a 25.4% improvement in the external quantum efficiency. Additionally, the spectral distortion according to the viewing angle was alleviated, which was confirmed by the negligible difference in the International Commission on Illumination 1931 color space coordinates (∆(x, y) = (0.01, 0.013)). The optical performance of the nRRS–OLED was predicted through a finite-difference time-domain simulation and verified by showing results consistent with those of the fabricated device. This research is expected to be widely applied in many optical devices because it is possible to form a random corrugation on the outside of the device without the difficulty of simply fabricating a beneficial optical structure.