Highly Efficient Tandem Polymer Photovoltaic Cells

Polymer tandem solar cells with a PCE of 5.8% are demonstrated by employing a p-n junction as an interlayer between the two subcells. The role of the interlayer and several important issues of the tandem structure is addressed including optical optimization, interfacial engineering, and accurate efficiency characterization (see image). It is revealed that the interlayer acts as a metal/semiconductor contact as opposed to a traditional tunnel junction in inorganic tandem cells.