We successfully realized world first 77-inch transparent flexible OLED display with Ultra High Definition (UHD) resolution, which can be rolled up to a radius of 80 mm with a transmittance of 40%. The process flow and key technologies to fabricate a large size transparent flexible OLED panel will be discussed.
Copper(I) oxide (Cu 2 O), which is obtained from copper(II) oxide (CuO) through a reduction process, is a p-type oxide material with a band gap of 2.1−2.4 eV. However, the switching performance of typical Cu 2 O thin-film transistors (TFTs) is poor because the reduction process increases the concentration of oxygen vacancies (V O ), which interfere with the conduction of hole carriers. Ga with high oxygen affinity was doped in Cu 2 O thin films to decrease V O during the reduction process. As a result, the V O concentration of 1.56 at % for Ga-doped Cu 2 O (Ga:Cu 2 O) thin films decreased from 20.2 to 7.5% compared to pristine Cu 2 O thin films. Accordingly, the subthreshold swing or S-factor, on/off-current ratio (I on/off ), saturation mobility (μ sat ), and threshold voltage (V th ) of Ga:Cu 2 O TFTs were improved compared to pristine Cu 2 O TFTs with values of 7.72 from 12.50 V/dec, 1.22 × 10 4 from 2.74 × 10 2 , 0.74 from 0.46 cm 2 /Vs, and −4.56 from −8.06 V, respectively. These results indicate that Ga plays an important role in improving the switching performance of p-type Cu 2 O TFT.
QD-OLED device performance is unsatisfactory nowadays, due to the limited efficiency of blue OLED material as well as the low efficient converting rate of QD material. Here we proposed a novel structure of QD-OLED, using white OLED as the excitation. The device shows higher optical efficiency compared with QD-OLED with Blue OLED as excitation. In addition, a 6.6 inch green QD-OLED was demostrated with the proposed structure.
We investigated the lateral distribution of the equilibrium carrier concentration (
n
0
) along the channel and the effects of channel length (
L
) on the source-drain series resistance (
R
ext
) in the top-gate self-aligned (TG-SA) coplanar structure amorphous indium-gallium-zinc oxide (a-IGZO) thin-film transistors (TFTs). The lateral distribution of
n
0
across the channel was extracted using the paired gate-to-source voltage (
V
GS
)-based transmission line method and the temperature-dependent transfer characteristics obtained from the TFTs with different
L
s.
n
0
abruptly decreased with an increase in the distance from the channel edge near the source/drain junctions; however, much smaller gradient of
n
0
was observed in the region near the middle of the channel. The effect of
L
on the
R
ext
in the TG-SA coplanar a-IGZO TFT was investigated by applying the drain current-conductance method to the TFTs with various
L
s. The increase of
R
ext
was clearly observed with an increase in
L
especially at low
V
GS
s, which was possibly attributed to the enhanced carrier diffusion near the source/drain junctions due to the larger gradient of the carrier concentration in the longer channel devices. Because the lateral carrier diffusion and the relatively high
R
ext
are the critical issues in the TG-SA coplanar structure-based oxide TFTs, the results in this work are expected to be useful in further improving the electrical performance and uniformity of the TG-SA coplanar structure oxide TFTs.
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