Enhanced efficiency of polymer: fullerene bulk heterojunction solar cells with the insertion of thin Pyronin B layer near the Al electrode

摘要

We show that the insertion of thin interfacial layers of pyronin B between the conjugated polymer-methanofullerene blend and Al electrode enhances the open-circuit voltage (Voc) and short-circuit current density (Jsc). The cells based on blends of poly[2-methoxy,5-(3',7'-dimethyl-octyloxy)]-p-phenylene vinylene (MDMO-PPV) and [6,6]-phenyl C61 butyric acid methyl ester (PCBM) with the pyronin B layer (~ 1.5 nm) shows Voc~0.86 V, Jsc~3.36 mA/cm2 and the power conversion efficiency of ~1.46 % under white light photoexcitation of about 80 mW/cm2, similar to the effect of thin LiF layer. Compared to cells without the Pyronin B layer, the power conversion efficiency increases up to about 40 %. Similar effect is also obtained in poly(3-octylthiophene) (P3OT)-PCBM blends. The increased solar cell performance can be attributed to enhanced carrier extraction efficiency at the polymer blend/Al interfaces when pyronin B was inserted. This effect is considered as the reduced Al work function with the thin Pyronin B interfacial layer.