This paper explores how different layers in an organic light emitting diode (OLED) impacts its performance. Here, different layers of OLED similar to hole/electron injection layer, transport layer, and block layers are analyzed. Four experimental devices are taken into consideration and their results are compared to one over another to analyze the impact of every layer. Inside depth analysis is also performed on the device to inspect what really is happening Innermost of the OLED. It is noticed that hole and electron block layer are instrumental in improving the device luminescence performance and efficiency. There is an improvement of 16, 37 and 38% in the luminescence of the device when hole block layers and electron block layers are added. Internal device analysis reveals that increase in charge carrier concentration and carrier confinement are the reason for this improvement.

Impact of different layers on performance of OLED

Interfacial fracture investigation of patterned active matrix OLED driven by amorphous-Si TFTs under film-type packaging technology

Computational study on CH3-functionalized Tetraphenyl-1,4-phenylenediamine: A hole-transporting material for OLED devices

P‐218: Late‐News‐Poster: On the Scalability of On‐Cell Touch for Flexible AMOLEDs

Organic light-emitting diodes (OLEDs) materials have occupied significance in device applications due to their lightweight, thin, quick switching speed, flexible, easy to fabricate and low-cost features. The 8-quinolinolato-lithium (Liq) is commonly used as an electron injector in the layer of OLEDs. Herein, we study 8-quinolinolato-sodium (Naq) and 8-quinolinolato-potassium (Kq) and compare them with Liq using density functional theory approach. We analyze the molecular structure of 8-quinolinolate-alkali (Mq) for M=Li, Na and K and notice that the structure of Mq remains planar for all the three substitutions. The increased dipole moments of Mq with the change of substitution (M) suggest that its enhanced solubility in polar solvents, which tends to reduce the electron injection barrier. Furthermore, the higher polarizability of Naq and Kq indicates that the molecule is chemically more reactive than Liq and therefore, is expected to respond quickly when the field is applied. Moreover, the electron affinities of Mq increase with the substitution of Na and K, which is also desirable for improved electron transport behavior. However, the reorganization energy of Naq and Kq is slightly higher than that of Liq, which is not desirable for the transport of charge carriers in OLED devices. Therefore, the findings of this study demand further assessment for the application of Naq and Kq instead of Liq in OLED devices.

Computational study on 8-quinolinolato-alkali, an electron transporting material for OLED devices

The work employs the finite element method (FEM) to model the touch on the flexible ultra-thin touch sensor panel for analyzing touch characteristics and signals. Touch sensor panel readout circuits typically depend on touch signals to determine whether the touch sensor panel is touched or not. However, the ultra-thin touch sensor panel encountered a problem which cannot correctly recognize touch points on this type of touch sensor panel (TSP) on active-matrix organic light emitting diodes (AMOLED) displays since its electrical characteristics are different from the one of the conventional TSP. The modeling techniques for the flexible ultra-thin touch sensor panel on an AMOLED display is used to analyze touch signals from the influence of the thickness of top over layer of the flexible ultra-thin TSP and to observe the variations of mutual capacitance from touch on the flexible ultra-thin TSP. When the flexible ultra-thin touch sensor panel with the thickness of the top over layer less than the threshold thickness of the top over layer is on multi-touch, the phenomenon of the ghost points are generated. The simulation to find the threshold thickness of the top over layer based on the FEM model is conducted, and the simulation results show the top layer thickness should be larger than 107 µm to eliminate the ghost points. Furthermore, a new solution that is an optimization of the electrode pattern of transmitters and receivers in the ultra-thin touch sensor panel to further minimize the threshold thickness of the top over layer of TSP without changing the physical structure of TSP is proposed. The results conducted by using this proposed solution show that TSP top over layer threshold thickness can be reduced to 65 µm without appearance of the ghost points.

Modeling and analysis of touch on flexible ultra-thin touch sensor panels for AMOLED displays employing finite element methods

With the development of flexible electronics, flexible microheaters have been applied in many areas. Low power consumption and fast response microheaters have attracted much attention. In this work, systematic thermal and mechanical analyses were conducted for a kind of flexible microheater with two different wire structures. The microheater consisted of polyethylene terephthalate (PET) substrate and copper electric wire with graphene thin film as the middle layer. The steady-state average temperature and heating efficiency for the two structures were compared and it was shown that the S-shaped wire structure was better for voltage-controlled microheater other than circular-shaped structure. In addition, the maximum thermal stress for both structures was from the boundary of microheaters, which indicated that not only the wire structure but also the shape of micro heaters should be considered to reduce the damage caused by thermal stress. The influence resulting from the thickness of graphene thin film also has been discussed. In all, the heating efficiency for flexible microheaters can be up to 135 °C/W. With the proposed PID voltage control system, the response time for the designed microheater was less than 10 s. Moreover, a feasible fabrication process flow for these proposed structures combing thermal analysis results in this work can provide some clues for flexible microheaters design and fabrication in other application areas.

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Chuan-Xin Chen

Papers

Modeling and analysis of touch on flexible ultra-thin touch sensor panels for AMOLED displays employing finite element methods

Design and Thermal Analysis of Flexible Microheaters