Figure 6.

Schematic ofV_ocin ITO/PEDOT:PSS/MEH-PPV:C₆₀(+ZnCdTe)/Al blend film devices with concentration of ZnCdTe. For an undoped MEH-PPV:C₆₀device,V_ocis dominated by the system of MEH-PPV:C₆₀(V_oc1). With the increasing concentration of ZnCdTe, the limitation for resultingV_oc, corresponding to an MEH-PPV:C60 (+ZnCdTe) composite device, at the negative electrode gradually shifts towards the LUMO energy level of ZnCdTe (V_ocn). When the LUMO of acceptor (ZnCdTe) completely acts as the limitation forV_oc, the resultingV_occan be expressed byV_oc2