SnO2-TiO(2 )Hybrid Electron Transport Layer for Efficient and Flexible Perovskite Solar Cells

Abstract

Inorganic electron transport layers (ETLs), such as titanium dioxide(TiO2) and tin dioxide (SnO2), are important in n-i-p structured perovskitesolar cells (PSCs). In particular, the ETLs forflexible PSCs (f-PSCs) using apolymer substrate require strong adhesion with a transparent conducting oxide(TCO) and formation of a uniform thinfilm at a temperature below 150 degrees C.Hence, SnO2colloidal nanoparticles are primarily used to meet these demands.Nevertheless, there exist further opportunities for improvement in terms ofefficiency, uniform coating, and adhesion on TCO. In this study, we prepared aSnO2-TiO2hybrid electrode by adding a certain amount of TiO2nanosol, whichfunctions as an inorganic binder, to a SnO2colloidal solution. In comparison withthe SnO2colloid alone, f-PSC fabricated with a SnO2-TiO2hybrid electrodedemonstrated not only better mechanical reliability against bending due to strongadhesion to the substrate but also greatly improved efficiency because of improvedenergy alignment. Eventually, the SnO2-TiO2hybrid electrode resulted in an efficiency of 21.02% and even an efficiency ofover 16% in a mini-module (7x7cm2) due to the uniform coating over a large area. This study provides a new strategy for theETL of high-efficiency f-PSCs