The influences of polyol process parameters on the optoelectronic characteristics of AgNWs-based flexible electrodes and their application in ITO-free polymer solar cells

Abstract

Abstract Silver nanowires (AgNWs) have been considered as promising materials for fabrication of transparent conducting electrodes (TCEs) due to their suitable optical and electrical conductivity. The current work investigates the effects of the synthesis parameters on the physical and morphological properties of AgNWs-based TCEs and the photovoltaic performances of ITO-free AgNWs-electrode based flexible polymer solar cells (FPSCs). AgNWs were prepared using two different polyol-based methods including modified polyol (MP) and Sigma polyol (SP) processes. These methods differed in the type of applied seed, ratios of PVP/AgNO3 and AgNO3/seed, AgNO3 injection rate and temperature. The reflux condition was used as a novel effective parameter in the MP method. Results showed that MP-AgNWs possessed higher aspect ratio compared to those obtained from the SP process. AgNWs-based TCEs were prepared using spin coating method. The injection volume and the thickness of AgNWs-electrodes were altered to find the optimized electrodes in terms of sheet resistance (Rs) and transparency. The optimized MP-AgNWs and SP-AgNWs electrodes based on H-FoM calculations showed different Rs of 11.3 and 99.3 Ω.sq−1 and transparency of 92.8% and 90.4%, respectively. These electrodes were integrated as the photo-anode in the construction of ITO-free FPSCs. The prepared FPSCs based on the optimized MP-AgNWs electrodes showed PCE of 3.18% which was about 28% higher than that obtained using the best SP-AgNWs electrodes. The photovoltaic performance of MP-AgNWs electrode based FPSC was found to be very close to those of ITO-based reference cell prepared using similar conditions. However, the PCE of these FPSCs was about 18% lower which can be improved by altering the synthesis parameters.