Effect of rate of deposition on opto-electrical characteristics of vapor deposited MoO3/Ag/MoO3 transparent electrode for photovoltaic applications

Abstract

Following an approach combining optical modeling and experimental study in this proposed work, we report designing and fabrication of MoO3/Ag/MoO3 transparent electrode (MAM-TE) for perovskite solar cell (PvSC) applications. We started with the optical design of the TE to determine the optimized thickness of the alternating layers. Variable angle spectroscopic ellipsometry was employed to find the accurate optical constants of each layer which works as the input parameter for the Transfer Matrix Method (TMM) based Matlab code. With the help of optical modeling, the optimum thickness of the undercoat and overcoat oxide layer is calculated. The thickness of the metal layer (Ag) is kept fixed at 9 nm as it is found to be thick enough to provide good electrical conductivity. In this work, we investigated the effect of the rate of deposition (RoD) of sandwiched Ag layer on the optical and electrical behavior of MAM-TE. For a better understanding of the effect of RoD on Ag, characteristics of Ag films are performed via scanning electron microscopy (SEM) and optical absorption spectroscopy (UV–Visible). Transmittance spectra revealed that as the RoD of the Ag layer is increased from 0.5 Å/s to 5 Å/s, the films become more transparent, which is in good agreement with SEM images of the deposited Ag films. In this way, keeping the RoD of the Ag layer fixed at 5 Å/s, we successfully fabricate a highly transparent MAM-TE with an average visible transmittance > 77 %, along with a sheet resistance < 5 Ω/□. After the complete optimization of fabricated TE, it is finally incorporated into a perovskite solar cell device architecture consisting of FTO/TiO2/MAPI/Spiro/MAM. The preliminary results of the fabricated PvSC give a power conversion efficiency (PCE) of 4.79 %. Hence, the fabricated TE can integrate routes for its revolutionizing applications in diverse fields, including optoelectronic industries and bifacial photovoltaics applications.