Multi-Dimensional Physically Unclonable Functions: Optoelectronic Variation-Induced Multi-Key Generation from Small Molecule PN Heterostructures

In this era of demanding invulnerable security systems against the threat of hacking, physically unclonable functions (PUFs), especially in which can spawn multiple security keys within a single device, has gained attention. This investigation explores the multi-key generable PUF devices employing organic small molecules, specifically C8-BTBT and PTCDI-C13. The variation stems from the formation of irregular PN junctions, haphazardly configured grain boundaries of C8-BTBT. A comprehensive analysis including scanning electron microscopy (SEM), atomic force microscopy (AFM), kelvin probe force microscopy (KPFM), impedance spectroscopy (IS), and optical simulation, has been substantiated the underlying mechanisms. Exploiting the photo-responsive characteristics within the light wavelength spectrum of 660 and 530 nm, alongside the electrical characteristics, the capability to generate a total of 30 distinct multi-security keys in a single device is been successfully. These keys, distinguished by variable parameters such as voltage, light wavelength, and the calculated photo-to-dark current ratio (PDCR), manifest novel quantitative and qualitative dimensions in security protocol customization. Inter-Hamming distance and entropy of these cryptographic keys exhibit commendable averages of 51.9–53.1%, and 0.81, respectively. Moreover, a noteworthy average bit-aliasing mean value of 51.9%, derived from four distinct batches, underscores the pragmatic feasibility of the proposed conceptual framework for PUF devices.