High performance polythiophene/fullerene bulk-heterojunction solar cell with a TiOx hole blocking layer

Insertion of a TiOx layer between the Al electrode and the active layer of an organic photovoltaic cell resulted in a high performance with 94% durability under irradiation (100 mW/cm(2)) for 100 h and had improved fill factor and open circuit voltage. An efficiency of 4.05% was achieved by using the cell containing a TiOx layer fabricated and measured in ambient atmosphere. The TiOx layer works as an effective barrier to physical damage and chemical degradation, resulting in high durability under aerobic conditions, and also serves as a hole blocking layer, resulting in improved parallel resistance and rectification. (C) 2007 American Institute of Physics.