Achieving uniform electrical performance by regulating domain structure in aligned DPPT-TT: PMMA blended layers

Polymer field-effect transistors (PFETs) hold significant promise for flexible displays. However, their widespread application is hindered by performance non-uniformity arising from vatiations in chain alignment and domain structures. This paper optimizes the electrical uniformity by integrating the Langmuir-Blodgett (LB) technique with poly (methyl-methacrylate) (PMMA) blending in aligned copolymer DPPT-TT semiconductor layers. The LB process enhances molecular orientation, strengthening π-π intermolecular interactions. The on-current of parallel-channel devices reaches 27 μA, which is a 20 % increase compared to orthogonal-channel devices. Incorporating PMMA (DPPT-TT:PMMA = 1:0.4) optimize film morphology, exhibit a more uniform threshold voltage of 4.3 ± 2.1 V, compared to 5.5 ± 3.4 V for those without PMMA. Similarly, the sub-threshold swing is more consistent at 6.5 ± 0.9 V/dec with PMMA, versus 6.7 ± 1.1 V/dec without it. The trap density of devices with PMMA is 3.0 × 10¹² eV⁻¹cm⁻², which is a 75 % reduction compared to devices without PMMA. These results demonstrate a scalable strategy for fabricating high-uniformity PFETs, advancing their applicability in flexible circuits.