Thick C60:ZnPc bulk heterojunction solar cells with improved performance by film deposition on heated substrates

We study the influence of different substrate temperatures during the deposition of the ZnPc:C60 blend layer in bulk heterojunction organic solar cells. It is shown that substrate heating during evaporation leads to a significant improvement in the solar cell performance mainly due to an increase in photocurrent and fill factor (FF). This is attributed to improved morphology resulting in better charge carrier percolation pathways within the ZnPc:C60 blend, leading to reduced transport losses. Using this method, blend layer thicknesses of 150 nm are possible without loss in FF, which requires a three-dimensional interpenetrating network without isolated clusters. When heating the substrate up to 110 °C, an efficiency of 2.56% is achieved compared to 1.59% for an identical device prepared at room temperature.