Full-organic flexible non-volatile memory diodes target application in low cost storage media and RFID owing to their compatibility with solution processing. The active layer of such devices is processed from a single solution and consists of a phase separated blend of a ferroelectric (e.g. PVDF, P(VDF-TrFE)), and a semi-conducting polymer (e.g. P3HT, F8BT). Charge injection into semiconducting domains dispersed in the ferroelectric matrix is hindered or facilitated by switching the polarization direction of the ferroelectric phase. Device performance strongly depends on the length scales characterizing the blend morphology as charge injection is modulated by local warping of the electric field at domain boundaries. This effect is not achieved for lateral domain sizes below 50 nm. Vise-versa, much larger domains render the bulk of the semiconductor inactive. The blend film morphology formation can be effectively controlled by micro-contact printing of the anodic substrate with self-assembled monolayers in order to create a well-defined wettability pattern. Subsequent solution phase demixing on top of such a pattern yields a morphology with features dictated by the interplay between i) the emerging length scale of the dominant spinodal mode of the mixture and ii) the enforcing length scale(s) associated with the surface pattern. We investigate by experimentation and full 3D numerical modeling how the morphological expression of the pattern depends on blend ratio. We assess dynamic scrambling in both the lateral and vertical direction and show how numerical simulations are in good qualitative agreement with the microscopic representations of the dry blend films. Finally it is shown that surface-directed morphology control indeed considerably enhances device performance by raising the on-off current ratio by at least an order of magnitude.