Robustness of organic physically unclonable function with buskeeper circuit for flexible security devices

Flexible devices have been studied to realize IoT or novel wearable devices. The data that flexible devices deal with can include personal information when application areas further expand. A security system for flexible devices becomes more important in this case. In this study, we investigate the thermal stability of an organic flexible security system. The security system utilizes fabrication variation of a chip, and it is called a physically unclonable function (PUF). As a result, the bit error rate of the organic PUF is 1.8% and the index of ID uniqueness (i.e., randomness) has an almost theoretical value of 0.48. The generated ID remains even after annealing at 100 °C for 97 h by using CYTOP encapsulation. X-ray diffraction measurement implies that degradation of PUF characteristics partially derives from structure changes of the organic n-type semiconductor thin film after annealing.