Electron Transporting Bilayer of SnO_2 and TiO_2 Nanocolloid Enables Highly Efficient Planar Perovskite Solar Cells

摘要

Herein, commercially accessible SnO_2 and home-made TiO_2 nanoparticles as acombined electron transporting bilayer (ETBL) are applied to achieve highly efficientplanar perovskite solar cells (PSCs). With the formed cascade-aligned energylevels from the proper stacking of SnO_2 and TiO_2 layers and the excellent defectpassivationability of TiO_2, SnO_2/TiO_2 ETBLs effectively reduce energy loss andinhibit defects formation both at the electron transporting layers (ETL)/perovskiteinterfaces and within the bulk of perovskite layer as revealed by a comprehensiveanalysis of photoelectric characteristic analysis, including ultraviolet photoelectronspectroscopy, photoluminescence, and electrochemical impedance spectroscopy.Consequently, the PSC devices acquired a power conversion efficiency (PCE) of20.50% with a V_(oc) of 1.10 V, a J_(sc) of 24.2 mA cm~(-2) and an fill factor of 77%, whichare superior to the values of the control device based on single SnO_2 layer with aPCE of 18.09% (a 13.3% boosting on PCE). Moreover, there was no degradationafter 49 days, indicating the great stability after adding TiO_2 layer. Herein, it isdemonstrated that the cascaded alignment of energy levels between the electrodeand perovskite layer by ETBLs could be an effective approach to improve thephotovoltaic performance of the PSCs with excellent long-term stability.