2 research outputs found
Passivation of Organic–Inorganic Hybrid Perovskite with Poly(lactic Acid) to Achieve Stable Red-Light Flexible Films
Low-dimensional organic–inorganic hybrid perovskites
(OIHPs)
have shown significant potential in the optoelectronic field due to
their adjustable structure and properties. However, the poor air stability
and flexibility of the OIHP crystals limit their further development.
Herein, three OIHP crystals have been synthesized using cadmium chloride
and the isomer of phenylenediamine as raw materials. Mn2+ doping turns on the red-light emission of Cd-based OIHPs at around
625 nm. Interestingly, the organic ligands with different steric hindrance
can induce a transition of the OIHP structure from two dimensions
(2D) to one dimension (1D), thereby regulating the quantum yield of
red luminescence in the range of 38.4% to nearly 100%. It is found
that the surface-exposed amino groups are easy to oxidize, resulting
in the instability of these OIHP crystals. Therefore, poly(lactic
acid) (PLA) is selected to passivate OIHPs through hydrogen bonding
between CO of PLA and –NH2 on the surface
of OIHPs. As a result, the production of OIHP-based flexible films
with highly efficient and stable red emission can be obtained after
being encapsulated by PLA. They demonstrate enormous application potential
in flexible X-ray imaging. This study not only realizes stable perovskite
films but also provides an effective design idea for red flexible
scintillators
High Color Rendering Index White-Light Emission from UV-Driven LEDs Based on Single Luminescent Materials: Two-Dimensional Perovskites (C<sub>6</sub>H<sub>5</sub>C<sub>2</sub>H<sub>4</sub>NH<sub>3</sub>)<sub>2</sub>PbBr<i><sub>x</sub></i>Cl<sub>4–<i>x</i></sub>
Two-dimensional
(2D) white-light-emitting hybrid perovskites (WHPs) are promising
active materials for single-component white-light-emitting diodes
(WLEDs) driven by UV. However, the reported WHPs exhibit low quantum
yields (≤9%) and low color rendering index (CRI) values less
than 85, which does not satisfy the demand of solid-state lighting
applications. In this work, we report a series of mixed-halide 2D
layered WHPs (C<sub>6</sub>H<sub>5</sub>C<sub>2</sub>H<sub>4</sub>NH<sub>3</sub>)<sub>2</sub>PbBr<i><sub>x</sub></i>Cl<sub>4–<i>x</i></sub> (0 < <i>x</i> <
4) obtained from the phenethylammonium cation. Unlike the reported
WHPs including (C<sub>6</sub>H<sub>5</sub>C<sub>2</sub>H<sub>4</sub>NH<sub>3</sub>)<sub>2</sub>PbCl<sub>4</sub>, the mixed-halide perovskites
display morphology-dependent white emission for the different extents
of self-absorption. Additionally, the amount of Br has a huge influence
on the photophysical properties of mixed-halide WHPs. With the increasing
content of Br, the quantum yields of WHPs increase gradually from
0.2 to 16.9%, accompanied by tunable color temperatures ranging from
4000 K (“warm” white light) to 7000 K (“cold”
white light). When applied to the WLEDs, the mixed-halide perovskite
powders exhibit tunable white electroluminescent emission with very
high CRI of 87–91