Enhancement of perovskite solar cell performance by external down‐conversion of Eu‐complex film.

Summary: Organic‐inorganic lead halide perovskite solar cells (PSCs) have shown excellent characteristics for photovoltaic performance along with high power conversion efficiency (PCE) of 25.5%. Methylammonium lead iodide (CH3NH3PbI3) PSCs show effective photovoltaic performance but exhibit low utilization and instability in the ultraviolet (UV) region due to photodegradation. Therefore, there is a need for research aimed at increasing the stability of PSCs. Through their down‐conversion, PSCs can achieve high photovoltaic performance and stability by protecting against UV light and light‐harvesting in the visible region. In this study, europium (Eu; a lanthanide) was demonstrated to enhance the efficiency of PSCs and prevent degradation by UV light. The Eu‐complex poly(dimethylsiloxane) (PDMS) film enhanced the usability of the UV region by down‐converting UV light to visible light. In addition, Eu‐complex PDMS film has the advantages of being transparent and hydrophobic. Furthermore, it is easily detachable when the surface is contaminated. When Eu‐complex PDMS film was attached and compared with a reference device, it was confirmed that the PCE increased by up to 20% and that the short‐circuit current density also increased. Overall, Eu‐complex film was shown to increase the light‐harvesting of PSCs and enhance the stability in the UV region through the down‐conversion of UV light to visible light. [ABSTRACT FROM AUTHOR]