Multi‐Level Anti‐Counterfeiting and Optical Information Storage Based on Luminescence of Mn‐Doped Perovskite Quantum Dots

Abstract

Traditional fluorescent anti‐counterfeiting labels can be easily cloned due to the lack of sufficient security. Therefore, multilevel anti‐counterfeiting techniques with higher security need to be constantly explored. This study reports a multilayer composite structure containing Mn doped CsPbCl3 (Mn:CsPbCl3) perovskite quantum dots (PQDs) layer and CsPbBr3 PQDs layer. The encrypted information is patterned on the Mn:CsPbCl3 PQDs layer with weak orange fluorescence, which is concealed by the brighter green fluorescence of CsPbBr3 PQDs at the upper layer. Based on the well‐separated photoluminescence (PL) peak positions, inverse PL temperature‐dependences and distinct PL lifetimes of these two PQDs, the encrypted information can be read out by adding cut‐off filter, heating and using ultrafast camera (UCA)/pulsed excitation (PE). This multilevel anti‐counterfeiting label significantly increases the difficulties of imitation meanwhile no expensive equipment is required for the verification of authenticity. Moreover, two bits of binary numbers that can be represented by dual emissions of the Mn:CsPbCl3 PQDs by changing the doping content, which significantly increases the information storage capacity, are also demonstrated.

Insights into the Impact of Fe-Doped CsPbCl3 Perovskites on Stability and Luminescence: A First-Principles Investigation

“…The trend of band gap increasing is consistent with the blue shift of experimental PL bands . Such an effect is also observed in the case of n-doped CsPbCl 3 . − In addition, the PBE method is well known to underestimate the band gaps of Pb-based perovskite systems, and it is very accurate to calculate their band gaps using the Heyd–Scuseria–Ernzerhof (HSE) hybrid functional method. Our obtained band gap of CsPb 1– x Fe x Cl 3 with HSE is 3.19, 3.24, and 3.28 eV for x = 0, 0.037, and 0.074, respectively.…”

Enhanced Exciton‐to‐Mn2+ Energy Transfer in 3D/0D Cesium–Lead–Chloride Composite Perovskites

“…halide perovskite arouses extensive attention. [10][11][12][13][14][15][16][17][18][19][20] In 2016, Liu et al [10] and Parobek et al [11] originally reported Mn 2+ -doped perovskite nanocrystals (NCs) with dual emission, where a broad emission located at ≈600 nm from Mn 2+ was observed in addition to the exciton emission at ≈400 nm. In their work, the emission of Mn 2+ has been fairly demonstrated to originate from the energy transfer of exciton-to-Mn 2+ .…”

Triple-Modal Anti-Counterfeiting Based on CsPbBr3 Perovskite Quantum Dot/CaAl2O4:Eu2+, Nd3+ Composites with Dual Fluorescence Properties

“…As known, all-inorganic cesium lead halide (CsPbX 3 , X = Cl/Br/I) perovskite quantum dots (PQDs) have attracted widespread attention in the fields of light-emitting diodes (LEDs), solar cells, displays, photoelectric detection, and anti-counterfeiting ,− owing to their distinguished properties such as large absorption coefficients, narrow-band emission, long carrier diffusion distance, tunable bandgap, and facile synthesis. There are currently two strategies to fabricate anti-counterfeiting devices based on CsPbX 3 materials.…”

“…One strategy is to design a reversible monochromatic PL ON/OFF switch to realize controllable information encryption–decryption through different induced methods such as water, methanol, EtOH, [DPA]­Cl, thermal, laser, and near infrared light. − Hydrochromic smart luminescent CsPbBr 3 -KBr composite materials were developed using a water–ethanol-assisted co-precipitation strategy, achieving reversible hydrochromic conversion through immersion or removal of water for information anti-counterfeiting . Another strategy is to design composites with other fluorescent materials for adjustable dual- or multiple-emission color changing by different stimulation patterns such as light or heat. − Dubey et al developed a bi-luminescent safety ink composed of Eu­(TTA) 3 Phen and CsPbBr 3 nanocrystals, which can be applied to dynamic anti-counterfeiting because of the distinctive phenomenon of the ink displaying red or green emission under UV or blue light excitation, respectively . Xiao et al designed a core–shell nanocomposite with nanocrystalline perovskite (CsMnCl 3 ) as the shell and NaYF 4 : Er 3+ , Yb 3+ up-conversion nanoparticles (UCNP) as the core, which exhibits adjustable luminescent patterns (green or blue) by changing the excitation source (980 nm laser or UV lamp) and shows great prospects in the security field .…”