A New Up-conversion Material of Ho3+-Yb3+-Mg2+ Tri-doped TiO2 and Its Applications to Perovskite Solar Cells

A new up-conversion nanomaterial of Ho 3+ -Yb 3+ -Mg 2+ tri-doped TiO 2 (UC-Mg-TiO 2 ) was designed and synthesized with a sol-gel method. The UC-Mg-TiO 2 presented enhanced up-conversion fluorescence by an addition of Mg 2+ . The UC-Mg-TiO 2 was utilized to fabricate perovskite solar cells by forming a thin layer on the electron transfer layer. The results display that the power conversion efficiency of the solar cells based on the electron transfer layer with UC-Mg-TiO 2 is improved to 16.3 from 15.2% for those without UC-Mg-TiO 2 . It is demonstrated that the synthesized UC-Mg-TiO 2 can convert the near-infrared light to visible light that perovskite film can absorb to improve the power conversion efficiency of the devices.