Structure-Guided Balancing of Ambipolar Transport Enables Symmetric Switching in Heterojunction Bilayer Organic Transistor Inverters

초록

High inverter performance in ambipolar organic electronics requires balanced channel strengths rather than maximized single-carrier mobility. Here, we demonstrate symmetric switching through balanced ambipolar transport in vertically stacked pentacene/N,N '-ditridecylperylene-3,4,9,10-tetracarboxylic diimide (PTCDI-C-13) heterojunction bilayers (HJBs) fabricated on polymer-grafted SiO2 dielectrics. By systematically tuning the nominal equivalent (1-4 monolayers, MLs) and thermal reorganization of the PTCDI-C-13 underlayer, a structural symmetry window is identified in which intermolecular self-assembly stabilizes both carrier mobility and threshold-voltage alignment. Under optimized conditions (3 ML, 150 degrees C annealed), nearly identical hole and electron mobilities (similar to 1.0 cm(2) V--(1) s(-)(1)) and convergent threshold voltages enable complementary-like inverters exhibiting high voltage gain (>200) and large noise margins under +/- 80 V operation. At absolute supply voltage (|V-DD|) = 80 V, the extracted low- and high-state noise margins are approximately 29.9-33.9 V, corresponding to approximately 75-85% of |V-DD|/2. Notably, imbalanced charge transport degrades switching symmetry despite improved unipolar mobility, revealing a non-monotonic relationship between molecular ordering and circuit performance. These results establish interface-mediated self-assembly as a structure-guided route for engineering transport symmetry in organic HJBs, while broader material generality and manufacturing scalability remain to be established.

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