Transparent, Low Resistance, and Flexible Amorphous ZnO-Doped In[sub 2]O[sub 3] Anode Grown on a PES Substrate

Abstract

Transparent and low resistance amorphous ZnO-doped In 2 O 3 ͑IZO͒ anode films were grown by radio-frequency ͑rf͒ sputtering on an organic passivated polyethersulfone ͑PES͒ substrate for use in flexible organic light-emitting diodes ͑OLEDs͒. Under optimized growth conditions, a sheet resistance of 15.2 ⍀/ᮀ, average transmittance above 89% in the green range, and a root mean square roughness of 0.375 nm were obtained, even for the IZO anode film grown in a pure Ar ambient without the addition of oxygen as a reactive gas. All of the IZO anode films had an amorphous structure regardless of the rf power and the working pressure due to the low substrate temperature of 50°C and the structural stability of the amorphous IZO films. In addition, an X-ray photoelectron spectroscopy depth profile obtained for the IZO/PES showed no obvious evidence of interfacial reactions between the IZO anode and the PES substrate, except for some indiffusion of oxygen atoms from the IZO anode. Furthermore, the current-voltageluminance of the flexible OLEDs fabricated on IZO anode was found to be critically dependent on the sheet resistance of the IZO anode.

Work function and interface control of amorphous IZO electrodes by MoO3 layer grading for organic solar cells

“…GAXRS plot of single layer IZO film exhibited a broad peak at 2θ ¼32.7°, indicating a completely amorphous structure formed by Zn doping, as was previously reported. The amorphous structure of the IZO films can be explained by the immiscibility of ZnO and In 2 O 3 [34]. In the case of MIZO films, another broad peaks was observed at 2θ ¼27.59°due to the presence of amorphous MoO 3 on the surface region of the IZO film.…”

Characteristics of flexible indium tin oxide electrode grown by continuous roll-to-roll sputtering process for flexible organic solar cells

“…The lower binding energy peak (O II ) is from the O 2À ions, which have neighboring indium atoms with their full complement, and the higher binding energy peak (O I ) corresponds to oxygen-deficient regions [25]. Because the increase of oxygen flow ratio leads to the incorporation of the oxygen atom into the ITO electrode, the flexible ITO electrode grown at the Ar/O 2 flow ratio of 30/3 shows lowest O II peak intensity, which is related to oxygen vacancies [26]. 10 shows the XRD plots obtained from the flexible ITO electrodes as a function of Ar/O 2 flow ratio.…”

“…However, some nanocrystallines, as indicated by arrows are embedded in the amorphous ITO matrix, due to the low amorphous/polycrystalline transformation temperature. Even if an ITO electrode is prepared at room temperature, nanocrystallines could be easily formed at the amorphous ITO matrix at a low homogeneous temperatures (T/T m o0.19-150 1C) [26,27]. It was shown that the flexible ITO layer is well defined on a PET substrate, indicating the absence of significant interfacial reactions between the ITO and the PET substrates due to the low substrate temperature.…”

Au coated amorphous indium zinc oxide (a-IZO) bilayer and its application as counter electrode for dye-sensitized solar cell

“…Unlike the most popularly studied amorphous ITO (indium tin oxide) that is easily crystalized at a low temperature, amorphous IZO has a much higher crystallization temperature than ITO. Therefore, amorphous IZO is more favorable than amorphous ITO as a conducting film on a flexible substrate because there are no grains and grain boundaries in an amorphous film, and there is much less chance to generate internal stress and severe film cracking [2]. Although amorphous IZO has these great advantages, it also has a big drawback of low conductivity especially when amorphous IZO is deposited at a low processing temperature.…”