An optoelectronic device comprises a first electrode; a first host material layer positioned over the first electrode; a second host material layer positioned over the first host material layer; at least one ultrathin dopant layer positioned between the first and second host material layers, the at least one ultrathin dopant layer having a thickness of less than 2 Å; and a second electrode positioned over the second host material layers. Other organic optoelectronic devices are also disclosed.