Highly Transparent and Low-Resistance Indium-Free ZnO/Ag/ZnO Multilayer Electrodes for Organic Photovoltaic Devices

Abstract

We investigated the effect of ZnO layer thickness on the optical and electrical properties of ZnO/Ag/ZnO multilayer films deposited on glass substrates. The transmission window became wider and shifted toward the lower energy side with increasing ZnO thickness. The ZnO/Ag/ZnO (40 nm/18.8 nm/40 nm) multilayer sample showed transmittance of $96% at 550 nm. As the ZnO thickness was increased from 8 nm to 80 nm, the carrier concentration gradually decreased from 1.74 9 10 22 cm À3 to 4.33 9 10 21 cm À3 , while the charge mobility varied from 23.8 cm 2 /V-s to 24.8 cm 2 /V-s. With increasing ZnO thickness, the samples exhibited similar sheet resistances of 3.6 X/sq to 3.9 X/sq, but the resistivity increased by a factor of 4.58. The samples showed smooth surfaces with root-mean-square roughness in the range of 0.47 nm to 0.94 nm. Haacke's figure of merit (FOM) was calculated for all the samples; the ZnO (40 nm)/Ag (18.8 nm)/ZnO (40 nm) multilayer produced the highest FOM of 148.9 9 10 À3 X À1 .

Transparent Conducting Electrodes for Efficient Organic Photovoltaic Devices under Indoor Light Conditions: A Brief Review

“…An oxide/metal/oxide structure can be utilized due to its electrical and optical advantages. ZnO/Ag/ZnO (ZAZ) electrodes are generally used as the conducting electrodes for various devices [27,28]. Lee OPVs with ZAZ electrodes [29].…”

Al-doped ZnO/Ag/Al-doped ZnO multilayer films with a high figure of merit

“…To improve our understanding of the dependence of the transmittance on d AZO , we conducted three-dimensional finitedifference time-domain (3D-FDTD) simulations [29,30]. For these 3D-FDTD simulations, a spatial resolution of 1 nm was imposed on all three orthogonal coordinates (x-, y-, and zaxes).…”

“…3 (a)). The dispersive optical constants of the Ag and AZO layers were applied to the 3D-FDTD simulations [29]. The simulated transmittance spectra (Fig.…”

ITO-Free Transparent Organic Solar Cell with Distributed Bragg Reflector for Solar Harvesting Windows

“…The metal oxide layers can efficiently suppress the reflection from the metal and achieve a high transmittance in the visible region. Silver was commonly used as the middle metal layer due to its low sheet resistance [28]. ZnO was chosen as the dielectric material because it is nontoxic, cheap, and abundant in nature [29].…”