It is still a great challenge to fabricate conjugated polymer monolayer field-effect transistors (PoM-FETs) due to intricate crystallization and film formation of conjugated polymers. Here we demonstrate PoM-FETs based on a single monolayer of a conjugated polymer. The resulting PoM-FETs are highly reproducible and exhibit charge carrier mobilities reaching 3 cm² V^-1 s^-1. The high performance is attributed to the strong interactions of the polymer chains present already in solution leading to pronounced edge-on packing and well-defined microstructure in the monolayer. The high reproducibility enables the integration of discrete unipolar PoM-FETs into inverters and ring oscillators. Real logic functionality has been demonstrated by constructing a 15-bit code generator in which hundreds of self-assembled PoM-FETs are addressed simultaneously. Our results provide the state-of-the-art example of integrated circuits based on a conjugated polymer monolayer, opening prospective pathways for bottom-up organic electronics.

In this work, the macroscopic polarization of a ferroelectric capacitor is correlated with the local domain morphology. To this end, a ferroelectric capacitor of the random copolymer poly(vinylidenefluoride-trifluoroethylene) [P(VDF-TrFE)] is poled to a set polarization state in a Sawyer-Tower setup. After chemically removing the top electrode, the exposed ferroelectric is locally probed with piezoresponse force microscopy. The domains without the top electrode are thermodynamically stable for weeks in ambient environment, as proven by comparing the remanent polarization measured before etching away and after re-depositing the top electrode. Out-of-plane PFM phase images show a random distribution of domains with up and down polarity. We unambiguously demonstrate a linear correlation between the mean PFM phase and the macroscopic polarization. As a demonstration of the insights that the global excitation and local probing method can provide, we show how thermal and electrical depoling can result in identical macroscopic polarization yet completely different domain morphologies.

Ultraviolet photoelectron spectroscopy (UPS) is a key technique to determine the work function (Φ) of surfaces by measuring the secondary-electron cut-off (SECO). However, the interpretation of SECO spectra as obtained by UPS is not straightforward for multicomponent surfaces, and it is not comprehensively understood to what extent the length scale of inhomogeneity impacts the SECO. Here, this study unravels the physics governing the energy distribution of the SECO by experimentally and theoretically determining the electrostatic landscape above surfaces with defined patterns of Φ. For such samples, the measured SECO spectra exhibit actually two cut-offs, one representing the high Φ surface component and the other one corresponding to an area-averaged Φ value. By combining Kelvin probe force microscopy and electrostatic modeling, it is quantitatively demonstrated that the electrostatic potential of the high Φ areas leads to an additional energy barrier for the electrons emitted from the low Φ areas. Theoretical predictions of the induced energy barrier dependence on the Φ-pattern length scale and sample bias are further experimentally verified. These findings establish a solid base for reliable SECO interpretation of heterogeneous surfaces and improved reliability of interfacial energy-level diagrams from UPS experiments.