SnO2 nanotube arrays grown via an in situ template-etching strategy for effective and stable perovskite solar cells

Abstract

For typical planar perovskite solar cell, an electron transporting layer (ETL) plays an important role in extracting electrons from a perovskite layer and blocking electron-hole recombination at the perovskite/conductive substrate interface. To date, TiO2 or ZnO ETLs are mainly adopted in both forms of film and nanostructure due to their ease of preparation. Nevertheless, the photoinstability of TiO2 and thermal instability of ZnO/perovskite interface remain the major challenges limiting their potential commercialization. Herein, we demonstrate an effective in situ template self-etching (iTSE) strategy to grow the novel hollow domed SnO2 nanotubes array with ZnO nanorods as sacrifice templates and the growth mechanism of such SnO2 nanotubes has been proposed based on a series of controllable experiments. Using such SnO2 nanotube as ETL for perovskite solar cell demonstrates a high photocurrent density of 15.9mA/cm2 at a based-voltage of 760mV, leading to a stable power conversion efficiency of 12.1% over 1000s under the simulated AM 1.5G one sun illumination. This work highlights the importance of the ETL material selection and provides insights into achieving an ideal ETL/substrate homojunction to facilitate electron transporting.