Low-Temperature Thermally Evaporated SnO2 Based Electron Transporting Layer for Perovskite Solar Cells with Annealing Process

Perovskite solar cells (PSCs) represent the third generation of solar cells that comprise a semiconductor electrode, a counter electrode, and an electrolyte. Perovskite solar cells (PSCs) have been comprehensively researched and led to an impressive improvement in a short period of time as cheaper alternatives to silicon solar cells due to their high energy-conversion efficiency and low production cost. Tin oxide (SnO2) has attracted attention as a promising candidate for electron transport material of perovskite solar cells, because it can be easily processed by low annealing temperature and solution processing method. However, in the fabrication of SnO2 electron transfer layer (ETL) via the conventional solution method, it is greatly difficult to increase the size of the substrate by the solution treatment method or to commercialize it. In this work, we report the photovoltaic characteristics of SnO2 based electron transport layer for perovskite solar cells (PSCs) fabricated by the thermal-evaporation processing method. The deposited SnO2 layer with the thermal evaporator is known to be not crystallographically stable. To solve this problem, we performed the annealing process at relatively low temperature (below 200 °C). As a result, we could confirm the optimum annealing temperature and we could demonstrate PSCs with thermally deposited SnO2 as the compact electron transport layer through a low-temperature annealing process. It would contribute to new opportunities in commercialization and development of perovskite solar cells.