Evidence of ambient doping in pentacene rectifying diodes

Organic rectifying diodes (ORDs) are a structurally simple yet functionally versatile element for advanced electronics. However, their operating principle, in association with the specificities of organic materials, is not well conceptualized. This study provides a comprehensive insight into a fundamental device phenomenon in ORDs, namely, ambient doping, and reveals for the first time its various footprints strongly affecting multiple in-device locations and operating regimes. High-performance pentacene-based diodes are fabricated and characterized in detail through current–voltage analysis, capacitance–voltage measurements, and broadband impedance spectroscopy. A highly analytical and correlative treatment of the whole data results in precise extraction of critical charge-injection, transport, and doping parameters, as well as a validated circuit model that systematically decouples the contact and bulk electronic processes governing the operation of ORDs.