Reconfigurable Electronic Physically Unclonable Functions Based on Organic Thin-Film Transistors with Multiscale Polycrystalline Entropy for Highly Secure Cryptography Primitives

In this study, organic thin-film transistors (OTFTs) are investigated as a promising platform for cost-effective, reconfigurable, and strong electronic physically unclonable functions (PUFs) for highly secure cryptography primitives. Simple spin-casting of solution-processable small-molecule organic semiconductors forms unique and unclonable fingerprint thin films with randomly distributed polycrystalline structures ranging from nanoscale molecular orientations to microcrystalline orientations, which provides a stochastic entropy source of device-to-device variations for OTFT arrays. Blending organic semiconductors with polymer materials is a promising strategy to improve the reliability of OTFT-based PUFs. Studies on the relationship between the phase-separated polycrystalline microstructure of organic semiconductor/polymer blend films and PUF characteristics reveal that the 2D mosaic microcrystalline structure of organic semiconductors in the vertically phase-separated trilayered structure enables the implementation of OTFT-based PUFs that simultaneously satisfy the requirements of being unclonable and unpredictable, with reliable cryptographic properties. The inherent multiscale randomness of the crystalline structure allows random distribution in OTFT-based PUFs even with various channel dimensions. The secret bit stream generated from the OTFT-based PUF developed in this study is reconfigurable by simply changing the gate bias, demonstrating the potential to counter evolving security attack threats.