In this work,a sky-blue luminescent down-shifting (LDS) layer bis[(4,6-difluorophenyl)-pyridinato-N,C2’]c(picolinate)iridium(Ⅲ) (Flrpic) was inserted between tetraphenyldibenzoperiflanthene (DBP) and MoO3 as UV-screen and sensitizer for small molecule DBP/C60 based planar heterojunction (PHJ) solar cells.With 8-nm Flrpic the short circuit current (Jsc) and power conversion efficiency (PCE) of the device are enhanced by 28％ and 15％,respectively,probably originating from the re-absorption of the photons emitted from Flrpic.The Voc linearly increases over 1-nm Flrpic,ascribed to the deeper HOMO level of Flrpic than DBP,while the fill factor continuously declines from 3-to 10-nm Flrpic.The EQE spectra prove that the Jsc is mainly contributed by the photocurrent generated in DBP and C60 layers.When the Flrpic thickness is 8 nm,the film surface is very uniform with the smallest water contact angle.The impedance spectroscopy demonstrates that the device resistance gradually increases from 4.1×104 Ω (without Flrpic) to 4.6×104 Ω (with 10-nm Flrpic) with the Flrpic thickness rise,simultaneously the device transits from the insulating state into the conductive state faster for the thin Flrpic layer than the thick layer.