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Ultrathin Metal Films as the Transparent Electrode in ITO‐Free Organic Optoelectronic Devices
| Content Provider | Semantic Scholar |
|---|---|
| Author | Bi, Yan-Gang Liu, Yuan Zhang, Xu-Lin Wang, Wen-Quan Feng, Jing Sun, Hong-Bo |
| Copyright Year | 2019 |
| Abstract | DOI: 10.1002/adom.201800778 wearable, and portable equipment.[2] Transparent conductive films, simultaneously with high conductivity and transmittance, are increasingly important elements as the optical and electrical windows to transform photons and charges in organic optoelectronic devices. Furthermore, stretchable and wearable devices, which represent the development tendency of modern electronic technologies, require the electrodes with the ability to be bent, compressed, twisted, stretched, and deformed into arbitrary shapes.[3] Indium tin oxide (ITO) is still the most commonly and widely used transparent conductive film, since it provides a relatively high and broadband transmittance of over 80% in the whole visible wavelength region and a particularly low sheet resistance of ≈10 Ω sq−1 with a thickness of ≈100 nm.[4] Despite the excellent optoelectronic properties, the use of ITO as the transparent electrode for organic optoelectronic devices is still suffering from several challenges. First, with fast developments in modern electronic equipment, the demand of ITO has increased rapidly, which is in contradiction with the lacking of the indium reserve in the earth, and the price of indium has risen over approx. $600 kg−1.[5] In addition, the inevitable material waste in the vapor-phase sputtering ITO process dramatically increases the cost. The typical cost of ITO with 10 Ω sq−1 has been up to $26 m−2.[6] Second, the intrinsically brittle ITO induces the risk of a catastrophic decrease in device performance owing to the formation of microscopic cracks, which damage the conductivity and surface morphology of the transparent electrode in mechanically flexible organic optoelectronic devices.[7] Third, the ion invasion and the waveguide mode induced by the high refractive index of ITO also impact the performance of optoelectronic devices.[8] Owing to the disadvantages of ITO, various research efforts have been conducted to develop desirable alternative transparent conductive electrodes, which can be fabricated by lowcost process with reasonable optoelectrical characteristics and robust structural durability for flexible and stretchable applications. Up to now, ITO-free optoelectronic devices with superior performance based on novel transparent electrodes, such as graphene,[9] carbon nanotubes,[10] conductive polymers,[11] metal nanowires,[12] metal meshes,[13] and ultrathin metal films,[14] have been within sight. Transparent conductive electrodes, as transmission windows of photons and electrons, play important roles in high-performance organic optoelectronic devices. The replacement of widely used indium tin oxide (ITO) electrodes has been attempted due to the increasing cost and intrinsically brittle characteristics of ITO. Ultrathin metal films, with excellent optoelectrical features, high flexibility, and sufficient mechanical stability, have been considered a potential candidate for the use as transparent conductive electrodes. However, ultrathin metal films follow the Volmer–Weber mechanism, resulting in a rough and discontinuous morphology with poor optoelectrical properties due to the bad adhesion to substrates. This review summarizes the progress in strategies for preparing ultrathin and ultrasmooth metal films with superior transmittance and conductivity by successfully suppressing the Volmer– Weber mechanism. The electrical and optical performances of the ultrathin metal films based on improved nucleation processes, as well as applications in ITO-free organic optoelectronic devices, are also described and discussed in detail. |
| Starting Page | 1800778 |
| Ending Page | 1800778 |
| Page Count | 1 |
| File Format | PDF HTM / HTML |
| DOI | 10.1002/adom.201800778 |
| Alternate Webpage(s) | http://www.lasun-jlu.cn/LaSuN/upload/file/publications/2019-BYG-AOM.pdf |
| Alternate Webpage(s) | https://doi.org/10.1002/adom.201800778 |
| Volume Number | 7 |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
