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

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.