Charge Transport Advancement in Anti-Ambipolar Transistors: Spatially Separating Layer Sandwiched between N-Type Metal Oxides and P-Type Small Molecules

Interface issues with organic semiconductors on metal oxide challenge realizing a high-performance anti-ambipolar transistor (AAT) with stable operation. The motivation behind this research delves into the intricate landscape of AATs, elucidating their envisioned applications and constituent materials. Central to the authors, discourse is the pivotal role that fluoropolymers assume, acting as a bridge uniting n-type metal oxide semiconductors (n-oxide) with p-type organic semiconductors (p-organic), thereby unveiling a hitherto concealed facet of transistor advancement. Adopting a spatially separating layer (SSL) between p- and n-type semiconductors of AAT is unconventional, but this p-organic/SSL/n-oxide junction (pSn) AAT exhibits stable operation also 215 days after fabrication and minimal hysteresis, which is 13.67 times smaller than a conventional p-organic/n-oxide junction (pn) AAT. The effect of SSL is closely studied through comparisons of the performance of single-type transistors, trap density, and carrier behavior, which define the order of 1/f at low-frequency noise analysis. In addition, the contribution of SSL is confirmed via the channel formation mechanism of AAT investigated through a two-dimensional (2D) finite-element simulation. The operation stability of pSn AAT is evaluated through combined stress tests, long-term stability tests, and transient response tests. This research proposes SSL as a new design parameter to improve the AAT.