# High-Capacity Optical Fingerprinting Using Dual-Peak Photoluminescence of Quantum Dots

## TL;DR

This paper introduces a secure optical fingerprinting method using quantum dots with dual-peak light emission to prevent counterfeiting.

## Contribution

A novel anticounterfeiting platform using dual-peak photoluminescence from CuInS2/ZnS quantum dots for high-capacity optical fingerprints.

## Key findings

- Dual-peak photoluminescence from a single quantum dot type enables inherently unclonable fingerprints.
- Spectral-to-digital processing generates binary fingerprints with a theoretical encoding capacity of 1.2 × 10^18.
- The system achieves an experimental error probability of ∼3 × 10^–17, demonstrating high security.

## Abstract

Counterfeiting and
unauthorized duplication continue to pose significant
threats across industries, ranging from electronics to pharmaceuticals.
In response to this challenge, we present a novel optical fingerprinting
platform based on cadmium-free CuInS2/ZnS quantum dots
(QDs), which exhibit a distinctive dual-peak photoluminescence (PL)
signature. Time-resolved PL (TRPL) analysis confirms the distinct
recombination origins of the two peaks, supporting the assignment
to core- and interfacial/shell-related states. Our approach extracts
two intrinsically coupled emissions from a single QD type, where both
peaks originate within the same nanostructure, making the fingerprint
inherently unclonable. This phenomenon enables the generation of rich
tunable spectral profiles across a selected range of excitation wavelengths.
Using spectral-to-digital processing, we extracted three features
from both emission peaks under 10 excitation wavelengths to generate
binary fingerprints. The resulting theoretical encoding capacity is
estimated to be 1.2 × 1018 compared to an experimental
error probability of ∼3 × 10–17. These
findings validate the strength and security of the proposed fingerprinting
system, highlighting its practical potential for anticounterfeiting
applications.