Inverted polymer solar cells with a boron-doped zinc oxide layer deposited by metal organic chemical vapor deposition

We report on the photovoltaic properties of inverted polymer solar cells (IPSCs) where the transparent indium tin oxide (ITO) electrode was modified by a ZnO layer using metal organic chemical vapor deposition (MOCVD). The intrinsic ZnO (i-ZnO) layers were deposited with varying thicknesses from 0 to 1500 nm. The work function and surface morphology of ITO/i-ZnO were found to be dependent on the i-ZnO thickness. When the thickness of the i-ZnO layer was 80 nm, optimized IPSCs with a power conversion efficiency (PCE) of 2.93% was achieved. Furthermore, the i-ZnO layer doped with boron (BZO) was investigated. The best IPSC with a BZO layer showed a PCE of 3.26%, which is higher than that (2.93%) of the device with the i-ZnO layer. The better performance is due to combined effects of improvement in charge collection and conductivity of BZO/ITO electrode.