Realization of Inverted Organic Solar Cells by Using Sol-Gel Synthesized ZnO/Y₂O₃Core/Shell Nanoparticles as Electron Transport Layer

In this article, we describe a simple, low-cost, and environment friendly sol-gel technique to form an effective protective Y2O3 layer over the core ZnO surface. The synthesized ZnO/Y2O3 core/shell nanoparticles have been studied for the investigation of morphology, purity, structure, luminescence, and electronic properties using different characterization techniques. The average particle size has been calculated to be 40 nm (approx). Scanning electron microscopy images show that the synthesized nanomaterials have particle-like morphology with spherical shape while high-resolution transmission electron microscopy analysis confirms their core/shell structure. Furthermore, ZnO/Y2O3 sample has been investigated as an electron transport layer (ETL) in inverted organic solar cell (OSC) with a blend of poly{4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b']dithio phene-2,6-diyl-alt-3-fluoro-2-[(2ethylhexyl)carbonyl]thieno [3,4-b]thiophene-4,6-diyl} (PTB7), and [6,6]-phenyl-C71-butyric acid methyl ester (PC71BM) as an active layer. On comparing with the standard device having pure ZnO as ETL, the power conversion efficiency of PTB7:PC71BM based device with ZnO/Y2O3 as ETL is efficiently improved from 5.77% to 6.22%. This study provides an economical method to increase the efficiency of OSCs.