Benefitting from methylene blue dye molecule for improving performance of perovskite photovoltaics

Abstract

Tin oxide (SnO2) has great potential as an electron transport layer (ETL) for low-cost and high-performance n-i-p-type perovskite solar cells (PSCs) due to its low annealing temperature, desirable optical transparency, and good n-type behaviors. However, the existence of defects at the surface and the relatively low charge transport/extraction behavior of SnO2 ETL restrict its widespread applications in PSCs despite the advantages of SnO2-based ETL. In this study, surface engineering is performed by modifying the SnO2 ETL layer with methylene blue (MB) dye with multiple functions in order to improve the surface contact of the SnO2 surface and decrease the defect states for better photovoltaic performance in PSCs. The comprehensive and systematic analyses demonstrate that after the modification of the SnO2 ETL, oxygen vacancies and surface defects of the SnO2 surface are reduced. As a result of these improvements, the device with the MB-SnO2-based ETL presents a power conversion efficiency (PCE) of 21.47 % with a short-circuit current (J(SC)) of 24.51 mA/cm(2), an open-circuit voltage (V-OC) of 1.109 V, and a fill factor (FF) of 0.79 compared to about 19.77 % of the reference cell. Moreover, the devices under 40-50 % humidity conditions at room temperature show that the devices that were treated with MB maintained over 80 % of their initial efficiency after 600 h, whereas the reference PSC retained only similar to 67 % of its initial efficiency. It is believed that this current report allocates an efficient surface engineering strategy via dye molecules for high-efficiency and stable PSCs.