ABSTRACT
The best way to increase the efficiency of solar cells is by making better use of the energy of the absorbed photons. By stacking more photoactive layers with complementary absorption spectra, the ultimate achievable efficiency increases dramatically. Organic tandem solar cells have evolved strongly in the past years to reach 10-12% power conversion efficiency in 2013. The development of the intermediate layers is crucial for tandem cells where energylevel alignment, conductivity, and compatible processing with the photoactive layers are major concerns. The optimization and characterization of tandem cells are more complicated than that of single junction cells because of the interdependence of the subcells. This chapter provides an overview of the recent literature of multijunction organic solar cells and discusses the options for further improving these novel devices.
