Solution-processed organic tandem solar cells with power conversion efficiencies >12%

An effective way to improve the power conversion efficiency of organic solar cells is to use a tandem architecture consisting of two subcells, so that a broader part of the solar spectrum can be used and the thermalization loss of photon energy can be minimized. For a tandem cell to work well, it is important for the subcells to have complementary absorption characteristics and generate high and balanced (matched) currents. This requires a rather challenging effort to design and select suitable active materials for use in the subcells. Here, we report a high-performance solution-processed, tandem solar cell based on the small molecules DR3TSBDT and DPPEZnP-TBO, which offer efficient, complementary absorption when used as electron donor materials in the front and rear subcells, respectively. Optimized devices achieve a power conversion efficiency of 12.50% (verified 12.70%), which represents a new level of capability for solution-processed, organic solar cells.