High efficiency multi-junction small-molecule photovoltaic devices

A multi-junction organic photovoltaic device comprising:

• two electrodes in superposed relation;
• a first subcell comprising a first organic donor and a first organic acceptor forming a first donor-acceptor heterojunction;
• a second subcell comprising a second organic donor and a second organic acceptor forming a second donor-acceptor heterojunction;
• a third subcell comprising a third organic donor and a third organic acceptor forming a third donor-acceptor heterojunction;
• a first separating layer;
• and
• a second separating layer,
• wherein the first, second, and third subcells are located between the two electrodes, the second subcell is located between the first and third subcells, the first separating layer is located between the first and second subcells, the second separating layer is located between the second and third subcells, and at least two of the first, second, and third subcells comprise small-molecule materials;
• wherein the first and third donors principally absorb at one or more overlapping wavelengths, and the first and third subcells are positioned at different optical interference maxima within the one or more overlapping wavelengths;
• wherein the second donor principally absorbs at one or more wavelengths that do not overlap with the one or more overlapping wavelengths principally absorbed by the first and third donors;
• and
• wherein the first and third donors principally absorb at shorter wavelengths than the second donor.