Time-dependent physical unclonable functions by long-lived triplet excitons in carbon dots.

Physical unclonable functions (PUFs), relying extensively on the random spatial distribution of block elements, are promising technology for generating unclonable cryptograph. Herein, we demonstrate time-dependent PUFs (TD-PUFs) by introducing carbon dots (CDs) with bright and long-lived triplet excitons as block elements. The constructed TD-PUFs evolve into multiple unclonable PUFs over time, effectively breaking the spatial limitation of transitional PUFs and increasing the complexity, making them much more difficult to be attacked. This temporal evolution introduces an additional layer of security, as the dynamic nature of TD-PUFs makes it increasingly challenging for adversaries to predict or replicate their states. We have developed pixel matrix function (PMF) to describe the evolution process of the TD-PUFs, enabling a detailed analysis of the dynamic behavior and unique security features. In addition, we exhibit a TD-PUFs painting (30 × 40 cm) by an etching technology where the primary structures of the panting undergo a transformation over time, driven by the varying triplet exciton lifetimes of the CDs. The proposed concept of TD-PUFs overcome their spatial limitations and increase the complexity, making the PUF labels more difficulty to be cracked.