Solution-processed composite electrodes composed of silver nanowires and aluminum-doped zinc oxide nanoparticles for thin-film solar cells applications

Abstract

Transparent conducting electrodes based on silver nanowires (AgNWs) have arisen great interest due to their excellent photoelectric properties compared with the conventional sputtered indium tin oxide (ITO) electrodes. However, the practical applications of these electrodes are limited due to their coarse surface morphology, weak mechanical adhesion and high junction resistivity as well as poor thermal and chemical stability. In this work, we develop a new processing technique to resolve all above limitations by embedding random AgNWs networks in solution-processed conductive aluminum-doped zinc oxide nanoparticles (AZO-NPs) matrices via a spin-coating process at low temperature (150°C). Our results show that coating the AZO-NPs on the surface of AgNWs networks effectively fill the holes between AgNWs and tightened the AgNWs junctions, resulting in ultralow surface roughness and excellent wire-substrate mechanical adhesion. Surrounding the AgNWs by conductive AZO-NPs could provide more electron transport channels between AgNWs so as to improve the wire-wire electrical conductivity. The resulting composite electrodes demonstrated an excellent performance with low sheet resistivity < 28Ω/sq, high optical transmittance > 91% at 550nm, excellent thermal stability at temperature as high as 270°C, good chemical corrosion resistance, and retained high electrical conductivity showing less 1% deviation in sheet resistivity after 300 continuous convex and concave bending cycle. Kesterite pure sulfide Cu2ZnSnS4 thin film solar cells using such composite electrodes as top contact show a best conversion efficiency of 7.45%, achieving a 11.5% increase compared with conventionally sputtered ITO-based CZTS thin film solar cells due to higher short circuit current density and fill factor.