Ultrathin Metal Films as the Transparent Electrode in ITO‐Free Organic Optoelectronic Devices

Abstract

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.

Patterned few nanometer-thick silver films with high optical transparency and high electrical conductivity

“…2d for further comparison, i.e., T 550 ¼ 85.7%, FoM ¼ 15.9 kU À1 , 29,49 and T 550 ¼ 92%, FoM ¼ 28.9 kU À1 . 60,61 The FoM of the 8.4 nm thick Ag grid TCE with OR ¼ 36% was much higher than that of our 29,49,60,61 and those of some metallic meshes with different thicknesses reported previously (indicated with different triangle symbols). [21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37] deposited ITO (FoM $ 0.6 kU À1 ) but was between the previously-reported ITO data in terms of both T 550 and R sh .…”

Vacuum‐Deposited Transparent Organic Photovoltaics for Efficiently Harvesting Selective Ultraviolet and Near‐Infrared Solar Energy

“…Highly transparent efficient electrodes are indispensable for novel electronic applications, such as transparent displays, [ 23 ] augmented reality glasses, [ 24 ] wearable sensors, [ 25–27 ] semitransparent solar windows, [ 28–30 ] etc. [ 31 ] Among these transparent anode or cathode electrodes, the electrodes with the multilayered structure, i.e., buffer layer/thin metal/buffer layer, provide efficient charge injection, high transparency, and excellent mechanical flexibility as compared to the standard transparent conductive oxides. [ 32 ] But, to achieve high AVT and PCE of a TPV, the transparent electrode should possess several particular optoelectrical properties.…”

Carbon Allotropes as ITO Electrode Replacement Materials in Liquid Crystal Devices

“…Figure 6b summarises the T-R performance of a collection of data on ultrathin metal films of Ag, Au, and Cu, produced by a variety of methods including seed layers and doping. The data can be found in tabular form in the excellent recent review on ultrathin metal films as transparent electrodes by Yan-Gang et al [86]. From the graph, it is apparent that ultrathin metal films can outperform ITO in terms of sheet resistance, which can be decreased to well below 10-20 Ω −1 .…”