Dielectric/Metal/Dielectric Flexible Transparent Electrodes, from Smart Window to Semi-transparent Solar Cells

Abstract

<jats:p>The present manuscript is dedicated to In free transparent conductive andflexible heterostructure electrodes. The new electrodes correspond todielectric/metal/dielectic (D/M/D) multilayer structures deposited under vacuum. In thepresent work, after a fast review of the general properties of D/M/D electrodes using Ag asmetal, we then develop the study of D/Cu/D multilayer structures. We propose to substituteCu to Ag, because it is far cheaper. However, Cu having tendency to diffuse into manydielectrics it is difficult to obtain stable electrodes. We show that using Cu:alloys, i.e. Cu:Niand Cu:Al, as metal it is possible to decrease significantly the Cu ions diffusion and toincrease significantly the stability of the multilayer electrodes with Cu. Finally, we show thatwhen these electrodes are used as anode in organic photovoltaic cells, they can allowachieving efficiency similar to that obtained with ITO.</jats:p>

Semi-Transparent Organic Photovoltaic Cells with Dielectric/Metal/Dielectric Top Electrode: Influence of the Metal on Their Performances

“…Nevertheless, since we know that Cu diffuses spontaneously into MoO3 [24], we introduced an ultra-thin Ag layer at the interface MoO3/Cu. We have already shown that such an ultra-thin Ag layer significantly improves the stability of MoO3/Cu structures [23]. Nevertheless, it is not sufficient to obtain really stable electrodes.…”

“…In the case of MoO 3 /Ag/MoO 3 structures, the optimum thickness of the layers has been determined in previous publications to be 20 nm/10 nm/35 nm, respectively [23]. The thickness of the Ag layer, 10 nm, corresponds to the percolation threshold of the metal layer; for less thickness, the metal film is discontinuous; for thicker films, the reflectivity and absorption of the metal film increase.…”

“…Below this thickness, the metal film is discontinuous, which results in enhanced absorbance due to plasmonic resonances, involving a decreased transmittance. For thicknesses beyond the threshold value, the reflectivity and absorbance of the metal layer increase, inducing a decreased transmission of light [21,23,32]. In the case of copper, it is not so easy to grow performing TCE.…”

“…In the case of the reference opaque electrode, the top electrode was MoO 3 /Al. We have already optimized the DMD structures, either as transparent conductive structures or as bottom electrodes in opaque OPVs [23,25]. Here, due to the fact that the DMD structures were deposited onto stacked ITO/Alq 3 /C 60 /SubPc layers, we had to check the optimum thickness of the MoO 3 interfacial layer.…”

“…Therefore, in the present work, MoO 3 was chosen as the dielectric. As for the metal, Ag is commonly selected because it exhibits the highest metal conductivity coupled with the lowest absorption in the visible range among the metals [23]. Nevertheless, Ag is quite expensive, and it would be of high interest to use a cheaper metal.…”