THESIS
2022
1 online resource (xxviii, 159 pages) : illustrations (some color)
Abstract
Recently, smart fluorescent materials, which respond to external stimuli, have attracted great
attention and are widely used in the fields of information security and encryption. However,
their drawbacks, such as low luminescence efficiency and complex processes, have strongly
hindered industrial application. Here, we have developed lead halide perovskite
nanocrystals/polymer composites as new intelligent fluorescent materials and exploited the
novel fluorescence responsive mechanisms, to provide higher-level information security
designs, which is expected to facilitate their commercialization in related fields.
Firstly, we have reported a challenging green in situ solvent engineering, to successfully
synthesize lead halide perovskite nanocrystals/polymer composites with aqueous assista...[
Read more ]
Recently, smart fluorescent materials, which respond to external stimuli, have attracted great
attention and are widely used in the fields of information security and encryption. However,
their drawbacks, such as low luminescence efficiency and complex processes, have strongly
hindered industrial application. Here, we have developed lead halide perovskite
nanocrystals/polymer composites as new intelligent fluorescent materials and exploited the
novel fluorescence responsive mechanisms, to provide higher-level information security
designs, which is expected to facilitate their commercialization in related fields.
Firstly, we have reported a challenging green in situ solvent engineering, to successfully
synthesize lead halide perovskite nanocrystals/polymer composites with aqueous assistance.
CH
3NH
3PbBr
3/polyvinylidene fluoride (MAPbBr
3/PVDF) powder derived from the air-dried
novel precursor successively achieved impressive productivity (512 mg/mL), higher
photoluminescence quantum yield (PLQY, 80%) and superb water resistance (< 3% decrease
in 2 months). More surprisingly, green precursor engineering shows strong generalizability to
a wide range of perovskite and polymers.
Then, a weak solvent engineering strategy based on perovskite nanocrystal/polymer composites
is reasonably designed in the encryption and decryption applications of confidential information.
By introducing and removing the weak solvent consisting of N,N-dimethylformamide (DMF)
and water, the perovskite-based composite could be quenched and restored, resulting in
reversible switching of the fluorescence signals. Surprisingly, this ON/OFF switch is highly
effective in encrypting and decrypting various types of information.
Moreover, we have proposed a new strategy for high-level multi-modal encryption/decryption
based on perovskite/polymer powders with homochromatic interference character. Two
analogous perovskite/polymer powders have excellent optical properties and stability and can
be used as mutual sources of interference in the encryption system, rendering their
decipherment more challenging. The discovery of the respective characteristic stimulus source
as the means of fluorescence recovery further constructs the confidential information system
through multi-dimensional encryption and dynamic anti-counterfeiting.
Finally, we have successfully synthesized CHN
2H
4 (FA)-based/PVDF porous films with low-dimensional
FA
m+2Pb
mBr
3m+2 perovskites inside. Water enters the film through the pores and
decomposes the excess FABr, which converts the non-fluorescent FA
m+2Pb
mBr
3m+2 into
fluorescent three-dimensional (3D) FAPbBr
3, achieving the unique hydrochromic character of
FA3.0/PVDF. Based on this, we have further developed the water-ink printing technology, and
unclonable 3D fluorescent fingerprint imaging will contribute to the development and design
of myriad innovations for data protection.
Post a Comment