A physically unclonable function (PUF) device is provided, comprising an excitation source providing light for exciting quantum dots (QDs); a first layer of a material having contained therein a first random distribution of first QDs of a first type that are configured to generate a first color in response to being excited by the excitation source; a second layer of a second material having contained therein a second random distribution of second QDs of a second type that are configured to generate a second color, different from the first color, in response to being excited by the first excitation source, and a detector fixedly attached to one of the first and second layers and configured for detecting a pattern of light emitted by at least one of the first QDs and the second QDs and for providing an output indicative of the detected pattern.