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Recent technological innovations in organic light-emitting diodes (OLEDs) have enabled their applicability to be expanded to not only displays but also the lighting industry. In addition, the high scalability and flexibility of OLEDs render them promising candidates for next-generation displays. However, their insufficient lifetime and low uniformity/stability are challenging issues, mainly because of inadequate understanding regarding the fundamental degradation mechanism of OLEDs owing to their complex device structure. Herein, based on impedance spectroscopy (IS), we report the origin of the relaxation frequency (fR) shift in blue OLEDs as a function of electrical stress time for up to 1000 h with a constant current stress condition of 1 mA. These experimental conditions allow us to separately study the degradation mechanisms of the emission and transport layer (TPL) interfaces. On the basis of thorough understanding of the theoretical expression of fR, we mainly attribute the variation in fR at the charge-balancing voltage to the degradation of the TPL interface; this is further rationalized by the negligible difference between fR values obtained from IS and the equivalent circuit theory. This strong correlation consequently renders fR a powerful degradation indicator for the TPL interface. Our results provide a basis for the realization of highly reliable blue OLEDs with a sufficient lifetime. [ABSTRACT FROM AUTHOR]

In this article, we described an innovative design technology of active matrix organic light emitting diode (AMOLED) display, to provide a bezel free design. We designed gate driver circuit of amorphous indium‐gallium‐zinc oxide thin‐film transistors (TFTs) not on the bezel area but within the active array. Although we applied challengeable design, no degradation of electrical/optical properties of panel was observed. Because we effectively prevented capacitive coupling and interference between the emission circuit and integrated gate driver circuit in active array, finally, we successfully demonstrated a bezel free designed AMOLED display of 18.3″ HD (1366 × 768) driven by a‐InGaZnO TFTs. [ABSTRACT FROM AUTHOR]

In this article, we described an innovative design technology of organic light emitting diode (OLED) display, to provide a bezel free design. To demonstrate it, we located gate driver circuit of amorphous indium‐gallium‐zinc oxide thin‐film transistors (TFTs) within the active array, and have successfully prevented capacitive coupling and interference between the emission circuit and gate driver circuit. Finally, we have successfully demonstrated bezel free designed OLED display of 18.3″ HD (1366x768, 85ppi) driven by a‐InGaZnO TFTs. [ABSTRACT FROM AUTHOR]

In this paper, we propose a new integrated gate driver circuit for random sensing operation of external compensated organic light‐emitting diode (OLED) display using oxide thin‐film transistor (TFT). Using this technology, we successfully launched 55‐inch and 65‐inch ultrahigh definition OLED TVs with gate in panel (GIP) circuit. The structure of the existing OLED TVs implemented gate signals through the gate integrated circuits (ICs) attached to the left and right sides of the panel. The structure using the gate IC was inferior to the panel structure using the GIP in terms of process and product design and cost. Thus, we propose a new oxide GIP circuit for OLED TV. Like the previous gate IC model, the proposed GIP circuit successfully implemented the random sensing function during the display operation. This GIP circuit is also designed to overcome the problems caused by the negative Vth characteristics of the oxide device. [ABSTRACT FROM AUTHOR]

This paper proposed a shift register circuit for GIP (Gate driver In Panel) in active matrix organic light emitting diode displays which enable cost innovation and narrow bezel. The shift register circuit which is made up with depletion mode oxide TFTs is designed to be driven at low operation frequency for power reduction in still image as well as to be driven at high operation frequency for motion picture quality improvement in moving image. However, it is especially difficult to operate at low frequency because oxide TFTs easily have negative Vth and zero gate-source voltage turns out to be unable to shut down current path. The proposed shift register is integrated in a 15-inch HD (1366 × 768, 105ppi) AMOLED panel, it is ensured that the shift register have wide operating frequency range from 1Hz to 240 Hz. In Addition, it is verified that the panel operates at high temperature(60°C) during 1,000 hours without any problems. [ABSTRACT FROM AUTHOR]