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a) Synthesis procedures of blue‐emissive Cs3Cu2I5 NCs. b) TEM, and c) HRTEM images of Cs3Cu2I5 NCs. d) Size distribution of Cs3Cu2I5 NCs. e) XRD patterns of Cs3Cu2I5 NCs. f) PL excitation (PLE) and PL emission spectra of Cs3Cu2I5 NCs. g) Time‐resolved PL decay curve of Cs3Cu2I5 NCs.
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Hydrochromic materials have attracted widespread attention in the fields of anti-counterfeiting because of their ability of the reversible light absorption and/or emission properties in response to water. Here, for the first it is demonstrated that the ternary copper halides Cs3Cu2I5 nanocrystals (NCs) possess excellent hydrochromic properties. The...
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Cesium lead halide perovskite nanocrystals have emerged as one of the most promising candidates for manufacturing portable lasers and light sources. In order to harness and exploit their photoluminescence more effectively, the nanocrystals are often accompanied by a photonic scheme that improves light emission. In this work, a quasi‐3D photonic cry...
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... Hence, this study delves into the water, thermal, and air stability of the freshly synthesized Cs 3 Cu 2 I 5 NGC, as illustrated in Fig. 4. The XRD patterns, photographs, and PL/PLE spectra in Fig. 4a show that the blue-emitting Cs 3 Cu 2 I 5 powder rapidly decomposes into yellow-emitting CsCu 2 I 3 after encountering water. This is attributed to the fact that Cs 3 Cu 2 I 5 decomposes into CsCu 2 I 3 + 2CsI under the catalysis of water [17,50]. However, due to the dense protection of B-N-A glass, Cs 3 Cu 2 I 5 cannot directly come into contact with H 2 O. ...
Cs3Cu2I5 materials exhibit significant potential in diverse application fields like LEDs, scintillation, photoelectric detection, and so on. However, their poor stability against moisture /water and singularity nature of emission band hinder their rapid utilization. Differing from the lattice or ligand modification methods commonly used, this work deftly integrates solid-state sintering and glass composite techniques to synthesize Cs3Cu2I5 nanocrystal-in-glass composite (NGC) with exceptional stability. Cs3Cu2I5 NGC demonstrated remarkable stability, maintaining its integrity even after immersion in an aqueous solution for 240 h or exposure to air for 180 days. Importantly, this proposed fabrication approach further utilizes the high solubility of glass materials for rare earth elements to solve the problem of the low solid solubility of Re3+ in Cs3Cu2I5. The full-spectrum tunable emission has been achieved in the composite of Re3+ and Cs3Cu2I5 materials for the first time. This study not only validates Re-Cs3Cu2I5 NGC as a promising fluorescent material but also establishes a novel method for fabricating composite materials based on rare-earth and copper perovskites, along with verifying their suitability in optical applications such as anti-counterfeiting and temperature measurement.
... These waterresistant nanocrystals were combined with bare Cs 3 Cu 2 I 5 to assemble sophisticated anticounterfeiting patterns relying on the water-induced structure transformation between blueemitting Cs 3 Cu 2 I 5 and yellow-emitting CsCu 2 I 3 . 20 However, the reported response performance of MHPs is still considered unsatisfactory. Few studies have reported the repetition of these water-responsive processes more than 20 times. ...
... The CsPbBr 3 @MnO 2 -M film which has been stored in air for 6 months still exhibits a reversible fluorescence quenching− recovery performance in a wetting−drying cycle, further confirming the stability of the composites ( Figure S16). Compared with the previously reported water/moistureresponsive metal halides, the CsPbBr 3 @MnO 2 -M film shows a more specified stimulus, dual-mode response in fluorescence and structural color and record-high durability (Table S2), 7,9,16,19,20,22,36,43 demonstrating its application potential on high-level optical anticounterfeiting and encryption. ...
... 16,17 A small percentage of lead-free perovskite NCs have been found to exhibit narrow-band blue light emission. [18][19][20][21][22] For example, Cs 3 Sb 2 Br 9 NCs obtained through ligand-assisted reprecipitation synthesis, display a narrow full width at half maximum (FWHM) (41 nm) in the blue region. 23 Han et al. reported that Cs 3 Bi 2 Br 9 NCs exhibit blue emission at 468 nm with a FWHM of 40 nm. ...
... This value is significantly higher than those reported for blue-emitting materials in Table 1, and higher than most of the currently reported bluelight lead-based perovskites (Table S2, ESI †). [18][19][20][21][22][23][24][29][30][31][40][41][42][43][44][45] In addition, we compared the physical parameters of CsEuBr 3 NCs with other lead-based perovskite NCs in the ESI † (Tables S2 and S3). CsEuBr 3 has large mobility, indicating the great potential for the application of CsEuBr 3 NCs. ...
Lead halide perovskite nanocrystals (NCs) are highly promising for backlighting display applications due to their high photoluminescence quantum yields (PLQY) and wide color gamut. However, the practical applications of blue...
... [23][24][25] In 2020, Zhang et al. reported a copper-based perovskite prepared by solvent-evaporation-induced crystallization at room temperature (25°C) and demonstrated the potential of Cs 3 Cu 2 I 5 for applications in hydrochromic anti-counterfeiting technologies. [26] Subsequently, by using thermal injection, Zhang et al., [27] prepared another Cs 3 Cu 2 I 5 nanocrystalline material having a PL QY of ≈90%. They demonstrated for the first time that Cs 3 Cu 2 I 5 nanofilms can achieve reversible hydrochromic conversion and high PL emissions. ...
... They demonstrated for the first time that Cs 3 Cu 2 I 5 nanofilms can achieve reversible hydrochromic conversion and high PL emissions. Unfortunately, the room-temperature-solvent -evaporation route is time consuming, and the thermal injection route is cumbersome because of complex temperature regulation, [25] the aqueous growth method, despite producing high-quality crystals, takes over 7 days and has complex temperature controls, making it unsuitable for bulk industrial preparation, [28] the Cs 3 Cu 2 I 5 nanocrystalline materials have poor stability in hydrochromic cycles, and practical techniques for their production remain lacking, [13,25,27,29,30] which has limited the commercial applications of Cs 3 Cu 2 I 5 . Therefore, the development of a facile synthetic method for crystalline Cs 3 Cu 2 I 5 having a higher PL QY and hydrochromic stability is necessary to expand its range of applications. ...
Cu‐based perovskites have excellent optical properties, environmental friendliness, and broad optical applications. However, their development is hindered by complex preparation methods and poor hydrochromic stability. In this work, a solvent‐evaporation‐based crystallization strategy combined with Sn doping for the preparation of Cs3Cu2I5 microcrystals (MCs) is reported. This strategy enhances the photoluminescence quantum yield (PLQY) and hydrochromic reliability. In addition, first‐principles calculations reveal the effect of Sn doping on the lattice structure and exciton–phonon coupling of the Cs3Cu2I5 MCs. The results show that Sn doping reduces the lattice spacing as a result of the substitution radius difference between Cu⁺ and Sn²⁺ ions, which causes stronger exciton–phonon coupling and enhances the PLQY. Moreover, the Sn‐doped Cs3Cu2I5 MCs show excellent reliability on heating and under hydrochromic cycles and long‐term luminescence conditions. Based on their hydrochromic and temperature‐responsive properties, the Sn‐doped Cs3Cu2I5 MCs are applied as encryptable printing materials for information encryption and decryption and as a fluorescence‐based temperature sensor, combined with Machine‐Learning to guide the manufacturing of fluorescent thermometers. The findings provide insights into the commercial value of copper‐based perovskites and demonstrate their potential anti‐counterfeiting, fluorescence temperature sensing applications.
... Recently, many external stimulus responsive lead-free metal halide luminescent materials have been reported, and they have achieved great progress in the fields of fluorescent anticounterfeiting, information encryption, optical logic gates, and so forth. [61][62][63][64][65] However, they generally exhibit single-model or double-model dynamic luminescent characteristics, which severely limit their further application. Developing new external stimulus responsive luminescent materials with triplet-mode and multimode dynamic luminescence switching characteristics is an effective strategy to enhance information security protection because they are rare and difficult to replicate. ...
Recently, many lead‐free metal halides with diverse structures and highly efficient emission have been reported. However, their poor stability and single‐mode emission color severely limit their applications. Herein, three homologous Sb ³⁺ ‐doped zero‐dimensional (0D) air‐stable Sn(IV)‐based metal halides with different crystal structures were developed by inserting a single organic ligand into SnCl 4 lattice, which brings different optical properties. Under photoexcitation, (C 25 H 22 P)SnCl 5 @Sb·CH 4 O ( Sb ³⁺ −1 ) does not emit light, (C 25 H 22 P) 2 SnCl 6 @Sb‐α ( Sb ³⁺ −2α ) shines bright yellow emission with a photoluminescence quantum yield (PLQY) of 92%, and (C 25 H 22 P) 2 SnCl 6 @Sb‐β ( Sb ³⁺ −2β ) exhibits intense red emission with a PLQY of 78%. The above three compounds show quite different optical properties should be due to their different crystal structures and the lattice distortions. Particularly, Sb ³⁺ −1 can be successfully converted into Sb ³⁺ −2α under the treatment of C 25 H 22 PCl solution, accompanied by a transition from nonemission to efficient yellow emission, serving as a “turn‐on” photoluminescence (PL) switching. Parallelly, a reversible structure conversion between Sb ³⁺ −2α and Sb ³⁺ −2β was witnessed after dichloromethane or volatilization treatment, accompanied by yellow and red emission switching. Thereby, a triple‐mode tunable PL switching of off–on I –on II can be constructed in Sb ³⁺ ‐doped Sn(IV)‐based compounds. Finally, we demonstrated the as‐synthesized compounds in fluorescent anticounterfeiting, information encryption, and optical logic gates.
... Especially, the 0D Cs 3 Cu 2 I 5 -related perovskites are considered as prospective materials for X-ray imaging owing to their near-unity PLQY. [14] However, 0D Cs 3 Cu 2 I 5 is highly sensitive to moisture, [15] and it will spontaneously transform into 1D CsCu 2 I 3 crystalline phase because of the high solubility of CsI in an aqueous environment. Unfortunately, the light yields of the CsCu 2 I 3 crystals are much inferior to the 0D Cs 3 Cu 2 I 5, which limits their applications in Xray imaging. ...
Metal‐halide perovskites have emerged as one of the most promising contenders for the next‐generation X‐ray scintillators on account of their large absorption coefficients, high light yields, and low‐cost fabrication. However, the existing X‐ray scintillators are plagued either by poor stability or high toxicity. Here, highly stable and flexible CsCu2I3@polymethyl methacrylate (PMMA) composite films are fabricated simply by a facile one‐step drop‐coating technique. Benefiting from the reasonable light yields (24 100 photons MeV⁻¹), short photoluminescence decay time (207 ns), and flat surface, a low detection limit of 39 nGyair s⁻¹ and a record‐high resolution of up to 25 lp mm⁻¹ are demonstrated in these CsCu2I3@PMMA composite films. The X‐ray imaging tests show that the CsCu2I3@PMMA composite films display excellent properties in the dynamic and irregular objects imaging. In addition, the CsCu2I3@PMMA composite films exhibit a desirable endurance to the high‐energy X‐ray's irradiation and the water erosion (photoluminescence quantum yield remains up of 90% of its initial value even after submersion in water for 300 h). This work provides a potential to develop eco‐friendly and highly stable halide perovskite materials for high‐resolution X‐ray imaging.
... 8,[12][13][14][15][16][17][18] Although luminescent anti-counterfeiting applications have been widely reported, advanced anti-counterfeiting materials with triple-mode luminescence are rarely reported. 8,12,[16][17][18][19][20][21] Lin et al. 19 prepared anticounterfeiting labels by adding the mixture of Tm:KYbF7@glass powders and CsPbBrxI 3−x perovskite nanocrystals@glass powders into a commercial blank white screen-printing ink to form the anti-counterfeiting ink, labeling the blue and the red under the excitation of near-infrared (NIR) and ultraviolet (UV) light, respectively. Moreover, the anti-counterfeiting ink exhibited the mixed blue and red emissions when excited by superimposed NIR light and UV light. ...
New fluorescent materials with a low cost, hypotoxicity, and concealment are desired for the application of anti-counterfeiting. Herein, we report a CsCu2I3@Cs3Cu2I5 composite with a triple-mode photoluminescence (PL) feature by simply adjusting the excitation wavelengths, which are ascribed to the multiple excited states of different phases in the CsCu2I3@Cs3Cu2I5 composite. The broadband emission and high quantum yield (∼51%) of the composite originate from the structure-oriented self-trapped excitons effect of Cs3Cu2I5 and CsCu2I3 phases. Moreover, the incorporation of polyethylene oxide (PEO) into this composite improves the stability of CsCu2I3@Cs3Cu2I5@PEO against harsh environments. The CsCu2I3@Cs3Cu2I5@PEO composite has a slight decay of ∼5% of its initial PL intensity and only a 3.5% shift of the corresponding color coordinate after 30 days of storage. More importantly, its initial PL intensity shows only 10.3% decay under ultraviolet exposure for 200 h. Our work provides a promising approach to design materials for advanced anti-counterfeiting applications.
... Hydrochromic materials that luminesce and respond to water are gaining popularity due to their simplicity, low cost, and ease of detection [230]. Their ability to reversibly change their light emission and absorption properties in response to moisture and dry air has made them famous for anti-counterfeiting [215]. Zhang et al. [215] prepared a ternary copper halides film of Cs 3 Cu 2 I 5 nanocrystals that emits blue and yellow light upon exposure/removal of water, which was used as ink for anti-counterfeiting encryption. ...
... Their ability to reversibly change their light emission and absorption properties in response to moisture and dry air has made them famous for anti-counterfeiting [215]. Zhang et al. [215] prepared a ternary copper halides film of Cs 3 Cu 2 I 5 nanocrystals that emits blue and yellow light upon exposure/removal of water, which was used as ink for anti-counterfeiting encryption. Bai et al. [231] developed efficient QDs for dual-mode optical anti-counterfeiting. ...
... [ [213][214][215] Photoluminescent (PL) materials Static PL-based anticounterfeiting and encryption have lowsecurity levels because encrypted information remains invariant during decryption, requiring complicated assembly for acceptable data read-in and storage. ...
... [13] Recently, lead-free perovskite phosphors including bismuth- (Bi), tin-(Sn), manganese-(Mn), indium-(In), copper-(Cu), and silver-(Ag) based alternatives have been designed and synthesized with highly efficient emission. [14,15] The high-quality lead-free perovskite phosphors have been widely used in the field of photodetectors, [16] solar cells, [17] remote optical thermometry, [18] information encryption, [19] anti-counterfeiting, [20] and X-ray scintillator screens. [21] The performance of lead-free devices is comparable to that of Pb-based perovskites. ...
Lead‐free halide perovskites are emerging as promising eco‐friendly candidates for next‐generation solid‐state lighting because of their nontoxicity and availability for broad emission. Herein, a modified room‐temperature anti‐solvent precipitation method is developed to synthesize the Sb³⁺‐doped, In‐based, lead‐free halide perovskites in microplate/microcrystal structure with different emission colors. The layered structure of InCl3 serves as the template for the growth of Cs2InCl5(H2O):Sb³⁺ microplate phosphors. Moreover, the presence of HCl not only improves the solubility of precursors, but also provides the acid etching effect. The resultant Sb³⁺‐doped Cs2InCl5(H2O) microplate phosphors show bright yellow emission with photoluminescence quantum yield up to 92.4%. Furthermore, Cs3InCl6:Sb³⁺ and Cs2NaInCl6:Sb³⁺ are synthesized through the similar method, which displays the bright green and deep‐blue emission, respectively. Subsequently, the proof‐of‐concept white light‐emitting diodes (WLEDs) are fabricated based on Cs2NaInCl6:Sb³⁺ + Cs2InCl5(H2O):Sb³⁺ and Cs2NaInCl6:Sb³⁺ + Cs3InCl6:Sb³⁺ + Cs2InCl5(H2O):Sb³⁺ phosphors, which achieves high‐quality white light with the color rendering index (CRI) of 91.6 and 95.4, respectively. The results greatly advance the development of lead‐free halide perovskite phosphors synthesis, which may offer new possibilities for high CRI WLEDs fabrication.
... Despite high expectation, the vast majority of smart luminescent LDHPs overwhelmingly dependent on the slight shift of emission wavelength with low contrast acting as colortunable PL switch, few approach has shown to realize PL offon switch [42][43][44]. The research deficiency attracts intensive attention to further explore more smart fluorescence switch by finely tuning the local structure of LDHP. ...
Intelligent stimuli-responsive fluorescence materials are extremely pivotal for fabricating luminescent turn-on switching in solid-state photonic integration technology, but it remains a challenging objective for typical 3-dimensional (3D) perovskite nanocrystals. Herein, by fine-tuning the accumulation modes of metal halide components to dynamically control the carrier characteristics, a novel triple-mode photoluminescence (PL) switching was realized in 0D metal halide through stepwise single-crystal to single-crystal (SC-SC) transformation. Specifically, a family of 0D hybrid antimony halides was designed to exhibit three distinct types of PL performance including nonluminescent [Ph3EtP]2Sb2Cl8 (1), yellow-emissive [Ph3EtP]2SbCl5·EtOH (2), and red-emissive [Ph3EtP]2SbCl5 (3). Upon stimulus of ethanol, 1 was successfully converted to 2 through SC-SC transformation with enhanced PL quantum yield from ~0% to 91.50% acting as “turn-on” luminescent switching. Meanwhile, reversible SC-SC and luminescence transformation between 2 and 3 can be also achieved in the ethanol impregnation–heating process as luminescence vapochromism switching. As a consequence, a new triple-model turn-on and color-adjustable luminescent switching of off–onI–onII was realized in 0D hybrid halides. Simultaneously, wide advanced applications were also achieved in anti-counterfeiting, information security, and optical logic gates. This novel photon engineering strategy is expected to deepen the understanding of dynamic PL switching mechanism and guide development of new smart luminescence materials in cutting-edge optical switchable device.
