2.6. Space−Charge−Limited−Current (SCLC)

Single carrier devices were fabricated and the dark J–V characteristics were measured and analyzed in the SCL regime following the previous literature. The architecture of the hole−only devices was glass/ITO/PEDOT:PSS (30 nm)/active layer/MoO_x (10 nm)/Ag (100 nm). The architecture of the electron−only devices was glass/ITO/ZnO (30 nm)/active layer/Ca (5 nm)/Ag (100 nm). The reported mobility data are the average values over the 18 devices of each sample for a range of thicknesses. The SCLC curves can be fitted to the Mott–Gurney relation for SCLC [28] as follows

where J_SCL is the current density, ε₀ε_r is the dielectric permittivity, µ is the carrier mobility, L is the film device, and β is the field activation factor [16].