A conjugated polymer poly (9,9-dioctyfluorene-co-benzothiazole) (F8BT) was used as the electron transporting layer (ETL) to modify the cathode interface of inverted planar perovskite solar cell. Incorporation of the thin F8BT layer delivered greatly enhanced power conversion efficiency (PCE) of 13.9% compared to the PCE 7.9% of the device without F8BT, due to the improvements in various performance parameters like V-oc,J(sc) and FF. Moreover, great elimination of the hysteresis was demonstrated in F8BT based devices. These results suggest promising potential of polymeric materials in perovskite solar cells and possible approach to eliminate the hysteresis of perovsldte solar cells with this class of interfacial materials. (C) 2016 Elsevier B.V. All rights reserved.