Compared with the mature inorganic silicon solar cells[1] and perovskite solar cells[2], OSC is slightly obviously immature in terms of short service life and bad power conversion efficiency (PCE)[3]. Therefore, how to improve its durability and PCE to promote its development has become the main research direction. For solar cells, one of the most effective methods to improve their performance is to introduce different materials to optimize the electron transport layer to improve the charge transport characteristics inside the cell[4]. For organic solar cells, it is to modify the existing materials, introducing organic[5] (e.g. conductive polymer or polyelectrolyte) and inorganic[6][7][8] (e.g. metal oxide) interface modification layers to optimize this layer, so as to realize the regulation of interface energy level and improve PCE.In this work, the method of introducing an organic interface modified layer and reasonable experimental steps is used to synthesize non-conjugated polymer polyimide derivatives (BDI-RO). Combined with various photoelectric test methods and according to the work function and optical band gap of the modified interface layer, the effect of using BDI-RO as a cathode interlayer on the performance of OSC is studied and discussed.