Enhanced charge transport in perovskite solar cells using WO3 and BaWO4 nanoparticles as alternative electron transport layers

Abstract

Perovskite solar cells (PSCs) represent a revolutionary step in photovoltaics due to their low-cost and scalable production. One of the crucial factors in the development PSC performance is selecting an effective electron transport layer (ETL). Conventional ETLs like TiO2 face challenges, including low conductivity and photocatalytic instability. This study explores tungsten trioxide (WO3) and barium tungstate (Scheelite; BaWO4) as alternative ETLs, aiming to address these challenges and provide more efficient solutions. In this work, the structural analysis via X-ray diffraction (XRD) confirmed higher crystallinity in BaWO4 than in WO3. Morphology assessments using SEM showed distinct nanoparticle formations. Optical studies revealed BaWO4 has lower absorbance across the spectrum, suggesting less interaction with visible light, which is beneficial for PSCs with a band gap energy of 3.69 eV compared to 2.29 eV for WO3, attributed to enhanced electron delocalization and trap states. Hall effect measurements indicated that BaWO4 has greater electron mobility (8.02 × 102 cm2V−1s−1) than WO3 (1.20 × 102 cm2V−1 s−1). Photoluminescence and cyclic voltammetry further highlighted BaWO4’s superior electrochemical performance. The lower peak-to-peak separation, indicative of improved charge transport. When implemented in PSCs, BaWO4 delivered an impressive PCE of 17.72%, outperforming 13.94% and 16.41% for WO3 and TiO2 as a reference, respectively, highlighting its potential as an advanced ETL material. Finally, these findings emphasize the urgent need for alternative and emergent ETLs materials in the PSCs field, underscoring this research’s importance and timeliness.