No abstract

This study investigated the effects of fluorine (F) diffusion from a CYTOP passivation layer into amorphous indium-gallium-zinc oxide (a-IGZO) thin-film transistors (TFTs). The F contained in the CYTOP passivation layer was diffused into a-IGZO through 350 °C annealing. The similar ionic radii of F and oxygen (O) allowed the passivation of oxygen vacancy (Vo) and weakly bonded oxygen by F. As a result, the a-IGZO TFTs with CYTOP passivation were highly stable under various stresses. The threshold voltage (Vth) shifts of a-IGZO TFTs without CYTOP passivation and with CYTOP passivation under a negative bias stress test for 10 000 s were −6.7 V and −2.5 V, respectively. In addition, the Vth shifts of each device under a negative bias illumination stress test for 4000 s were −10.9 V and −5.3 V, respectively. This improvement was caused by a reduction of Vo and a widened band gap of a-IGZO through the F diffusion effect. In addition, the CYTOP passivation layer maintained excellent properties as a barrier against moisture after 350 °C annealing.

No abstract

We demonstrate a novel structure for a quantum-dot light-emitting diode (QD-LED) with wide-range colour-tuneable pixels, fabricated via full solution processing. The proposed device has a symmetrical structure produced via stacking...

No abstract

We fabricated ultrathin flexible thin film transistors with hydrophobic encapsulation layer by debonding process. In the debonding process, to separate the transistors from the carrier glass in deionized (DI) water, a strong hydrophobic material such as CYTOP was used for encapsulation, thus increasing their resistance to moisture. PVA was used as a release layer and the debonding process was optimized to separate the carrier glass and the transistors. It was confirmed that water penetration into the device can be suppressed effectively when the CYTOP thickness is 800 nm. In addition, the electrical characteristics remained almost constant even in the presence of water for 50 min. The total thickness after debonding process was approximately 2 μm. Waterproof experiments and debonding process were performed for a simple inverter circuit as well as a discrete device, and the operation and voltage gain of the inverter did not change when water was placed on the device or after debonding process. Finally, the flexibility was measured by transferring the device to a flexible PI substrate. Consequently, it was confirmed that degradation in the electrical properties was slightly up to a bending radius of 2.5 mm.

In this paper, a novel gate driver circuit, which can achieve high reliability for depletion mode in a‐InGaZnO thin‐film transistors (TFTs), was proposed. To prevent the leakage current paths for Q node effectively, the new driving method was proposed by adopting the negative gate‐to‐source voltage (VGS) value for pull‐down units. The results showed all the VOUT voltage waveforms were maintained at VGH voltage despite depletion‐mode operation. The proposed circuit could also obtain stable VOUT voltage when the threshold voltage for all TFTs was changed from −6.5 to +11.5 V. Therefore, the circuit can achieve high reliability regardless of threshold voltage value for a‐IGZO TFTs. In addition, the output characteristics and total power consumption were shown for the alternating current (AC)–driven and direct current (DC)–driven methods based on 120‐Hz full‐HD graphics (1920 × 1080) display panel. The results showed that the AC‐driven method could achieve improved VOUT characteristics compared with DC‐driven method since the leakage current path for Q node can be completely eliminated. Although power consumption of the AC‐driven method can be slightly increased compared with the DC‐driven method for enhancement mode, consumption can be lower when the operation has depletion‐mode characteristics by preventing a leakage current path for pull‐down units. Consequently, the proposed gate driver circuit can overcome the problems caused by the characteristics of a‐IGZO TFTs.

No abstract