Surface Functionalization of Indium Tin Oxide Electrodes by Self-assembled Monolayers for Direct Assembly of Pre-synthesized SnO2 Nanocrystals as Electron Transport Layers

Abstract

Abstract: In this study, a (3-aminopropyl) triethoxysilane (APTES) monolayer was used as an adhesion promoter to assemble pre-synthesized SnO2 nanocrystal (NC) arrays for use as electron transport layers (ETLs) in perovskite solar cells. The self-assembled monolayers on indium tin oxide (ITO) bottom electrodes interact with the SnO2 NCs via covalent bonding during the spin-coating process, leading to the formation of pinhole-free SnO2 NC layers, which enabled the growth of perovskite films with uniform microstructures. The device performance analyses showed that the resulting photovoltaic efficiency significantly increased from 10.68% to 15.52% with the use of the APTES monolayer. This increase in the photovoltaic efficiency can be attributed to the reduction in defects at the ETL/perovskite interface and in the bulk. This paper presents a facile, robust, and effective strategy to improve the grafting of SnO2 NCs on flat ITO substrates by using APTES, and thus, increase the quality of the ETL/perovskite interfacial structure. Graphical Abstract: [Figure not available: see fulltext.]