Recent
discoveries in organic−inorganic metal halides reveal
superior semiconducting and polarization properties. Herein, we report
three organic–inorganic metal halides, (PBA)4BiBr7·H2O, (PBA)4BiI7·H2O, and (PBA)4InBr7·H2O [(PBA)+ = C6H5(CH2)4NH3
+], with band gaps of ∼3.52,
∼2.29, and ∼4.05 eV, respectively. They possess zero-dimensional
structures containing the inorganic octahedra [MX6]3– (M = Bi, In, X = Br, I) and unbound X– ions and crystallize in the C2 space group. (PBA)4BiI7·H2O shows a second-harmonic-generation
(SHG) response in the infrared region, approximately 1.3 times that
of AgGaS2; (PBA)4BiBr7·H2O and (PBA)4InBr7·H2O show SHG responses in the ultraviolet region, approximately 0.4
and 0.6 times that of KH2PO4, respectively.
The large SHG responses are attributed to the synergistic contribution
of the octahedral distortion of [MX6]3– (M = Bi, In, X = Br, I) and the ordered arrangement of the benzene
ring-containing organic cation PBA+. Upon ultraviolet and
visible-light excitations at room temperature, (PBA)4BiBr7·H2O, (PBA)4BiI7·H2O, and (PBA)4InBr7·H2O exhibit broad red-light luminescence with large Stokes shifts of
290, 237, and 360 nm, respectively, due to self-trapped exciton emission.
All of these properties demonstrate that this series of metal halides
are potential multifunctional optoelectronic materials.
Organic−inorganic hybrid metal halides have attracted widespread attention as emerging optoelectronic materials, especially in solid-state lighting, where they can be used as single-component white-light phosphors for white light-emitting diodes. Herein, we have successfully synthesized a zero-dimensional (0D) organic−inorganic hybrid mixed-metal halide (Bmpip) 2 Pb x Sn 1−x Br 4 (0 < x < 1, Bmpip + = 1-butyl-1-methyl-piperidinium, C 10 H 22 N + ) that crystallizes in a monoclinic system in the C2/c space group. Pb 2+ and Sn 2+ form a four-coordinate seesaw structure separated by organic cations forming a 0D structure. For different excitation wavelengths, (Bmpip) 2 Pb x Sn 1−x Br 4 (0 < x < 1) exhibits double-peaked emission at 470 and 670 nm. The emission color of (Bmpip) 2 Pb x Sn 1−x Br 4 can be easily tuned from orange-red to blue by adjusting the Pb/Sn molar ratio or excitation wavelength. Representatively, (Bmpip) 2 Pb 0.16 Sn 0.84 Br 4 exhibits approximately white-light emission with high photoluminescence quantum yield up to 39%. Interestingly, the color of (Bmpip) 2 Pb x Sn 1−x Br 4 can also be easily tuned by temperature, promising its potential for application in temperature measurement and indication. Phosphor-converted light-emitting diodes are fabricated by combining (Bmpip) 2 Pb x Sn 1−x Br 4 and 365 nm near-UV LED chips and exhibit high-quality light output.
Organic−inorganic metal halides (OIMHs) have various crystal structures and offer excellent semiconducting properties. Here, we report three novel OIMHs, (PPA) 6 InBr 9 (PPA = [C 6 H 5 (CH 2 ) 3 NH 3 ] + ), (PBA) 2 SbBr 5 , and (PBA) 2 SbI 6 (PBA = [C 6 H 5 (CH 2 ) 4 NH 3 ] + ), showing typical zero-dimensional (0D) structure, octahedra dimers, and corner-sharing one-dimensional chains and crystallized in the monoclinic system with P2 1 , P2 1 /c, and C2/c space groups, respectively. (PPA) 6 InBr 9 , (PBA) 2 SbBr 5 , and (PBA) 2 SbI 6 have experimental optical band gaps of ∼3.16, ∼2.24, and 1.48 eV, respectively. (PPA) 6 InBr 9 exhibits bright-orange light emission centered at 642 nm with a full-width at half-maximum of 179 nm (0.51 eV) and a Stokes shift of 277 nm (1.46 eV). After Sb 3+ doping, the peak position did not change, and the photoluminescence quantum yield increased significantly from 9.2 to 53.0%. The efficient emission of Sb:(PPA) 6 InBr 9 stems from the isolated ns 2 luminescent center and strong electron−phonon coupling, making the spin-forbidden 3 P 1 − 1 S 0 observable. By combining commercial blue and green phosphors with orange-red-light-emitting (PPA) 6 In 0.99 Sb 0.01 Br 9 , a white-light-emitting diode was constructed, with the color-rendering index reaching up to 92.3. Our work highlights three novel 0D OIMHs, with chemical doping of Sb 3+ shown to significantly enhance the luminescence properties, demonstrating their potential applications in solid-state lighting.
Recently,
excellent optical properties of low-dimensional organic–inorganic
metal halides, stemming from their tunable structure and optoelectronic
properties, have been demonstrated. The synthetic method is critical
because it is highly related to the structure and properties of the
halide. Herein, we obtain two different antimony bromides, (Bmpip)2SbBr5 and (Bmpip)3Sb2Br9, which both possess the P21/c space group having different crystal structures, and this
confirms the important influence of synthesis on the single-crystal
structure. (Bmpip)2SbBr5 contains Bmpip+ and [SbBr5]2– pyramids, and
(Bmpip)3Sb2Br9 consists of Bmpip+ and Sb-based dimers [Sb2Br9]3–. Under 400 nm excitation, (Bmpip)2SbBr5 exhibits
a 640 nm orange emission with a quantum yield of ∼11.5% owing
to Sb 5s2 electron luminescence. A diode was fabricated
by (Bmpip)2SbBr5 and commercial phosphors and
showed a high color render index of 92. Our work reveals the effect
of the preparation method on the crystal structure. A luminescent
material was finally identified.
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