Monolayer molecular diode

Abstract Molecular diodes are of considerable interest for the increasing technical demands of device miniaturization. However, the molecular diode performance remains contact-limited, which represents a major challenge for advancement of rectification ratio toward commercial availability. Here, we demonstrate that high-quality ultrathin organic semiconductor can be grown on several classes of metal substrates via solution-shearing epitaxy, with well-controlled number of layers and monolayer single crystal over 1 mm. The crystalline films are atomically smooth and free pinhole, providing a native interface for high-performance molecular diodes. As a result, the molecular diodes show record-high rectification ratio up to 5 × 108, ideality factor close to unity, aggressive unit conductance over 103 S/cm2, reverse breakdown electric field～1.1 × 108 V/cm, excellent electrical stability and well-defined contact interface. We further fabricate large-area molecular diode arrays with 100% yield and excellent uniformity in the diode metrics. Our results suggest that monolayer crystalline films have great potential to build reliable, high-performance molecular diodes and deeply understand their intrinsic electronic behavior.