Space charge limited current (SCLC) mobility measurements

Space charge limited current (SCLC) mobility measurements were performed on an Agilent Technologies B1500A Semiconductor Device Analyzer. Single carrier n-type devices were fabricated on ITO coated glass with a ZnO bottom interfacial layer and a Ca/Al top interfacial layer and electrode. The semiconducting layer was a 1 : 2.25 PBDTT-FTTE:PDI blend with 1% DIO added. Device areas were patterned to 200 × 200 μm². The current density (J) was measured as a function of the applied electric field (E), which was corrected for any built in bias and for sheet resistance of ITO (30 Ω) prior to fitting. The space charge limited regime data were fit to eqn (1), where ε_s and L are the

semiconductor permittivity, taken to be 3ε₀, and the film thickness, respectively.68 The ohmic regime data were fit with a low-field carrier density model using eqn (2).