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Broadband Emission Induced by Band-Edge Carrier Reconfiguration in 2D Hybrid Lead Halide Perovskites. SMALL METHODS 2024:e2301662. [PMID: 38634221 DOI: 10.1002/smtd.202301662] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2023] [Revised: 02/15/2024] [Indexed: 04/19/2024]
Abstract
Broadband emission in hybrid lead halide perovskites (LHPs) has gained significant attention due to its potential applications in optoelectronic devices. The origin of this broadband emission is primarily attributed to the interactions between electrons and phonons. Most investigations have focused on the impact of structural characteristics of LHPs on broadband emission, while neglecting the role of electronic mobility. In this work, the study investigates the electronic origins of broadband emission in a family of 2D LHPs. Through spectroscopic experiments and density functional theory calculations, the study unveils that the electronic states of the organic ligands with conjugate effect in LHPs can extend to the band edges. These band-edge carriers are no longer localized only within the inorganic layers, leading to electronic coupling with molecular states in the barrier and giving rise to additional interactions with phonon modes, thereby resulting in broadband emission. The high-pressure photoluminescence measurements and theoretical calculations reveal that hydrostatic pressure can induce the reconfiguration of band-edge states of charge carriers, leading to different types of band alignment and achieving macroscopic control of carrier dynamics. The findings can provide valuable guidance for targeted synthesis of LHPs with broadband emission and corresponding design of state-of-the-art optoelectronic devices.
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Broadband Profiled Eye-Safe Emission of LMA Silica Fiber Doped with Tm 3+/Ho 3+ Ions. MATERIALS (BASEL, SWITZERLAND) 2023; 16:7679. [PMID: 38138821 PMCID: PMC10744985 DOI: 10.3390/ma16247679] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/17/2023] [Revised: 12/13/2023] [Accepted: 12/15/2023] [Indexed: 12/24/2023]
Abstract
LMA (Large Mode Area) optical fibers are presently under active investigation to explore their potential for generating laser action or broadband emission directly within the optical fiber structure. Additionally, a wide mode profile significantly reduces the power distribution density in the fiber cross-section, minimizing the power density, photodegradation, or thermal damage. Multi-stage deposition in the MCVD-CDT system was used to obtain the structural doping profile of the LMA fiber multi-ring core doped with Tm3+ and Tm3+/Ho3+ layer profiles. The low alumina content (Al2O3: 0.03wt%) results in low refractive index modification. The maximum concentrations of the lanthanide oxides were Tm2O3: 0.18wt % and Ho2O3: 0.15wt%. The double-clad construction of optical fiber with emission spectra in the eye-safe spectral range of (1.55-2.10 µm). The calculated LP01 Mode Field Diameter (MFD) was 69.7 µm (@ 2000 nm, and 1/e of maximum intensity), which confirms LMA fundamental mode guiding conditions. The FWHM and λmax vs. fiber length are presented and analyzed as a luminescence profile modification. The proposed structured optical fiber with a ring core can be used in new broadband optical radiation source designs.
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Broadband Emission Origin in Metal Halide Perovskites: Are Self-Trapped Excitons or Ions? ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2023; 35:e2211088. [PMID: 36988940 DOI: 10.1002/adma.202211088] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/28/2022] [Revised: 03/20/2023] [Indexed: 06/19/2023]
Abstract
It has always been a goal to realize high efficiency and broadband emission in single-component materials. The appearance of metal halide perovskites makes it possible. Their soft lattice characteristics and significant electron-phonon coupling synergistically generate self-trapped excitons (STEs), contributing to a broadband emission with a large Stokes shift. Meanwhile, their structural/compositional diversity provides suitable active sites and coordination environments for doping of ns2 ions, allowing 3 Pn ( n =0,1,2) →1 S0 transitions toward broadband emission. The ns2 ions emission is phenomenologically similar to that of STE emission, hindering in-depth understanding of their emission origin, and leading to failure to meet the design requirements for practical applications. In this scenario, herein, the fundamentals and development of such two emission mechanisms are summarized to establish a clear and comprehensive understanding of the broadband emission phenomenon, which may pave the way to an ideal customization of broadband-emission metal halide perovskites.
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Dual Emission Bands of a 2D Perovskite Single Crystal with Charge Transfer State Characteristics. ACS NANO 2023. [PMID: 37366559 DOI: 10.1021/acsnano.3c00496] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/28/2023]
Abstract
Several hybrid halide 2D-perovskite species emit light with an emergent and controversial broadband emission Stokes-shifted down from the narrow band emission. This paper uncovers the sub- and above-bandgap emission and absorption characteristics of PEA2PbI4 prepared with gap states introduced during single crystal growth. Here, gap states led to coexistent intrinsic and heterostructured electronic frameworks that are selectively accessible with ultraviolet (UV) and infrared (IR) light, respectively, resulting in the phenomenon of photoluminescence (PL) switching from narrowband green to broadband red. Electron-energy dependent cathodoluminescence shows a relative increase in the broadband red PL intensity as the electron penetration depth increases from 30 nm to 2 μm, confirming the heterostructured framework is formed in the bulk of the crystal. Excitation-emission power slope of 2.5 and up-conversion pump transient absorption (TA) spectra suggest that the IR up-conversion excitation with red photoluminescence, peaked at 655 nm, is a multiphoton process occurring in the heterostructured framework through a nonlinear optical response. The energetic pathways toward the dual emission bands are revealed by pump-probe transient absorption spectroscopy, showing energetically broad gap states with high sensitivity to an IR pump are upconverted and subsequently quickly relax from high to low energy levels within 4 ps. Furthermore, the up-conversion red PL demonstrates a linear polarization with magnetic field effects, thus affirming that the band-like heterostructured framework is crystallographically aligned with characteristics of spatially extended charge-transfer states.
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Plant Growth Modeling and Response from Broadband Phosphor-Converted Lighting for Indoor Agriculture. ACS APPLIED MATERIALS & INTERFACES 2023. [PMID: 37364173 DOI: 10.1021/acsami.3c06454] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/28/2023]
Abstract
The rapid change in population, environment, and climate is accompanied by the food crisis. As a new type of farming, indoor agriculture opens the possibility of addressing this crisis in the future. In this study, a phosphor-converted light-emitting diode (pc-LED), as energy-saving lighting for indoor agriculture, was used to evaluate the response and effect on the growth of Lactuca sativa. Red phosphors, SrLiAl3N4:Eu2+ (SLA) and CaAlSiN3:Eu2+ (CASN), were characterized and analyzed with crystal structure, morphology, and optical properties. Eu2+-doped phosphors provided the red emission of around 650 nm which is highly matched with the absorption of chlorophyll. Under the same luminescence intensity, broader emission of CASN pc-LED demonstrated a 100% increase of photosynthetically active photon flux density and 130% promotion of plant weight than the SLA pc-LED, which reflected the positive result of the carbon fixation. The chlorophyll and nitrate responses have also revealed the effect of broader red light on indoor agriculture.
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Chromaticity-Tunable All-Inorganic Color Converters Fabricated by 3D Printing for Modular Plant Growth Lighting Devices. ACS APPLIED MATERIALS & INTERFACES 2023; 15:23527-23537. [PMID: 37140148 DOI: 10.1021/acsami.3c03881] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
In photopolymerization-induced 3D printing of glass and ceramics, the demand for a slurry that has high photosensitivity, low viscosity, and high solid content leads to a limited selection of suspended particles. To this end, ultraviolet-assisted direct ink writing (UV-DIW) is proposed as a new 3D printing compatible approach. A curable UV ink is synthesized, which overcomes the material limitation. Benefiting from the advantage of the UV-DIW process, CaAlSiN3:Eu2+/BaMgAl10O17:Eu2+ phosphors in glass (CASN/BAM-PiG) as chromaticity-tunable specially shaped all-inorganic color converters are prepared for plant growth lighting using an optimized heat treatment procedure. Size compatible dome-type and flat-type CaAlSiN3:Eu2+ phosphors in glass (CASN-PiG) are constructed in batches. The manufactured dome-type PiG-based light-emitting diodes (LEDs) exhibit better heat dissipation capacity and a larger divergence angle. The advantage of CASN/BAM-PiG in plant growth lighting is confirmed by the high degree of resemblance between the emission spectra of CASN/BAM-PiG and the absorption spectra of carotenoid and chlorophyll. A series of dome-type CASN/BAM-PiG based LEDs with selective region doping are constructed, which can weaken reabsorption effects and scientifically match the requirements of different plants. The excellent color-tunable ability and high degree of spectral resemblance indicate the superiority of the proposed UV-DIW process in all-inorganic CASN/BAM-PiG color converters for intelligent agricultural lighting.
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High-T c 1D Phase-Transition Semiconductor Photoluminescent Material with Broadband Emission. Chemistry 2023; 29:e202203893. [PMID: 36579748 DOI: 10.1002/chem.202203893] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2022] [Revised: 12/26/2022] [Accepted: 12/29/2022] [Indexed: 12/30/2022]
Abstract
One dimensional (1D) organic-inorganic halide hybrid perovskites have the advantages of excellent organic cation modifiability and diversity of inorganic framework structures, which cannot be ignored in the development of multi-functional phase-transition materials in photoelectric and photovoltaic devices. Here, we have successfully modified and synthesized an organic-inorganic hybrid perovskite photoelectric multifunctional phase-transition material: [C7 H13 ONCH2 F]⋅PbBr3 (1). The synergistic effect of the order double disorder transition of organic cations and the change of the degree of distortion of the inorganic framework leads to its high temperature reversible phase-transition point of Tc =374 K/346 K and its ultra-low loss high-quality dielectric switch response. Through in-depth research and calculation, compound 1 also has excellent semiconductor characteristics with a band gap of 3.06 eV and the photoluminescence characteristics of self-trapped exciton (STE) broadband emission. Undoubtedly, this modification strategy provides a new choice for the research field of organic-inorganic hybrid perovskite reversible phase-transition photoelectric multifunctional materials with rich coupling properties.
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Photoluminescence Properties of AScSi 2O 6:Cr 3+ (A = Na and Li) Phosphors with High Efficiency and Thermal Stability for Near-Infrared Phosphor-Converted Light-Emitting Diode Light Sources. ACS APPLIED MATERIALS & INTERFACES 2022; 14:8179-8190. [PMID: 35113521 DOI: 10.1021/acsami.1c23940] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Near-infrared (NIR) phosphors are fascinating photoluminescence materials with applications in phosphor-converted light-emitting diodes (pc-LEDs) for night vision lighting, which are still restricted by low efficiency and thermal stability in the current research stage. In this work, AScSi2O6 (A = Na/Li) are chosen as hosts due to a larger band gap and a single octahedral site for Cr3+ doping. The NIR-emitting Cr3+-activated AScSi2O6:Cr3+ phosphors were successfully prepared by a common high-temperature solid-state method. X-ray diffraction and Rietveld refinement confirm that the Cr3+ prefers to enter the Sc3+-octahedral lattice site in the AScSi2O6 structure. Under blue light excitation, AScSi2O6:Cr3+ phosphors exhibit broadband NIR emission from 700 to 1100 nm with a full width at half-maximum of ∼150 nm owing to the 4T2 → 4A2 electron transition of Cr3+. The photoluminescence properties were enhanced by adjusting the fluxes and sintering conditions, and highly efficient LiScSi2O6:Cr3+ NIR phosphors with external quantum efficiencies of 33.4% were obtained. Moreover, the optimized LiScSi2O6:Cr3+ exhibits excellent thermal stability (75% at 150 °C) with an activation energy of 0.33 eV. Importantly, the fabricated NIR pc-LED with the highly efficient LiScSi2O6:Cr3+ phosphor demonstrates brighter NIR light and a higher luminous efficacy than the NaScSi2O6:Cr3+ phosphor in night vision.
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Ni 2+-Doped Garnet Solid-Solution Phosphor-Converted Broadband Shortwave Infrared Light-Emitting Diodes toward Spectroscopy Application. ACS APPLIED MATERIALS & INTERFACES 2022; 14:4265-4275. [PMID: 35025207 DOI: 10.1021/acsami.1c20084] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Broadband shortwave infrared (SWIR) light-emitting diodes (LEDs), capable of advancing the next-generation solid-state smart invisible lighting technology, have sparked tremendous interest and will launch ground-breaking spectroscopy and instrumental applications. Nevertheless, the device performance is still suppressed by the low quantum efficiency and limited emission bandwidth of the critical phosphor layer. Herein, we report a high-performance Ni2+-doped garnet solid-solution broadband SWIR emitter centered at ∼1450 nm with a large full-width at half-maximum of ∼300 nm, thereby fabricating, for the first time, a directly excited Ni2+-doped garnet solid-solution phosphor-converted broadband SWIR LED device. A synergetic enhancement strategy, adding a fluxing agent and a charge compensator simultaneously, is proposed to deliver a more than 20-fold increase of the SWIR emission intensity and nearly 2-fold improvement of the thermal quenching behavior. The site occupation and mechanism behind the synergetic enhancement strategy are elucidated by a combination of experimental study and theoretical calculation. A prototype of the SWIR LED with a radiation flux of 1.25 mW is fabricated and utilized as an invisible SWIR light source to demonstrate the SWIR spectroscopy applications. This work not only opens a window to explore novel broadband SWIR phosphors but also provides a synergetic strategy to remarkably improve the performance of artificial SWIR LED light sources.
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Ultrafast Study of Exciton Transfer in Sb(III)-Doped Two-Dimensional [NH 3(CH 2) 4NH 3]CdBr 4 Perovskite. ACS NANO 2021; 15:15354-15361. [PMID: 34523914 DOI: 10.1021/acsnano.1c06564] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Antimony-based metal halide hybrids have attracted enormous attention due to the stereoactive 5s2 electron pair that drives intense triplet broadband emission. However, energy/charge transfer has been rarely achieved for Sb3+-doped materials. Herein, Sb3+ ions are homogeneously doped into 2D [NH3(CH2)4NH3]CdBr4 perovskite (Cd-PVK) using a wet-chemical method. Compared to the weak singlet exciton emission of Cd-PVK at 380 nm, 0.01% Sb3+-doped Cd-PVK exhibits intense triplet emission located at 640 nm with a near-unity quantum yield. Further increasing the doping concentration of Sb3+ completely quenches singlet exciton emission of Cd-PVK, concurrently with enhanced Sb3+ triplet emission. Delayed luminescence and femtosecond-transient absorption studies suggest that Sb3+ emission originates from exciton transfer (ET) from Cd-PVK host to Sb3+ dopant, while such ET cannot occur with Pb2+-doped Cd-PVK because of the mismatch of energy levels. In addition, density function theory calculations indicate that the introduced Sb3+ likely replace the Cd2+ ions along with the deprotonation of butanediammonium for charge balance, instead of generating Cd2+ vacancies. This work provides a deeper understanding of the ET of Sb3+-doped Cd-PVK and suggests an effective strategy to achieve efficient triplet Sb3+ emission beyond 0D Cl-based hybrids.
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Broadband Short-Wave Infrared Light-Emitting Diodes Based on Cr 3+-Doped LiScGeO 4 Phosphor. ACS APPLIED MATERIALS & INTERFACES 2021; 13:36011-36019. [PMID: 34289302 DOI: 10.1021/acsami.1c10490] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Short-wave infrared (SWIR) spectroscopy has recently emerged as an important technology across a wide range of areas, whether industrial, biomedical, or environmental. Nevertheless, it is still a long-standing challenge to develop robust SWIR light sources. The SWIR phosphor-convert light emitting diodes (LEDs) by coating blue LED chips with desirable SWIR-emitting phosphors are becoming an ideal alternative for solid-state SWIR light sources due to its compactness, low-cost, and long operating lifetime, as does the commercial white LEDs. Herein, we report a blue-pumped Cr3+-doped LiScGeO4 SWIR phosphor as a luminescent converter for phosphor-convert SWIR LEDs. This phosphor shows an intense SWIR emission band with a peak wavelength at ∼1120 nm owing to the 4T2 → 4A2 electron transition of Cr3+ when exciting with blue light. The full width at half-maximum (fwhm) of the phosphor is ∼300 nm and the absolute quantum efficiency is determined to be ∼26%. SWIR LED prototypes are constructed by combining the optimized phosphor materials with commercial blue InGaN LED chips, which can generate a commendable emission band in the SWIR region over 800-1600 nm and achieve a maximum output power of ∼4.78 mW at 60 mA with the photoconversion efficiency of 4.4%. The current exploration of Cr3+-doped SWIR-emitting phosphors will lay the foundation to engineer phosphor-convert SWIR LEDs for applications in night-vision surveillance and SWIR spectroscopy technology. These blue-light-excitable SWIR-emitting phosphors can serve as an important complement to the spectral gap of the current Cr3+-doped phosphors in the SWIR region and will pave the way toward cost-effective phosphor-converted solid-state SWIR light sources.
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Solid-State Thin-Film Broadband Short-Wave Infrared Light Emitters. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2020; 32:e2003830. [PMID: 32996211 DOI: 10.1002/adma.202003830] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/04/2020] [Revised: 08/14/2020] [Indexed: 05/28/2023]
Abstract
Solid-state broadband light emitters in the visible have revolutionized today's lighting technology achieving compact footprints, flexible form factors, long lifetimes, and high energy saving, although their counterparts in the infrared are still in the development phase. To date, broadband emitters in the infrared have relied on phosphor-downconverted light emitters based on atomic optical transitions in transition metal or rare earth elements in the phosphor layer resulting in limited spectral bandwidths in the near-infrared and preventing their integration into electrically driven light-emitting diodes (LEDs). Herein, phosphor-converted LEDs based on engineered stacks of multi-bandgap colloidal quantum dots (CQDs) are reported as a novel class of broadband emitters covering a broad short-wave infrared (SWIR) spectrum from 1050-1650 nm with a full-width-half-maximum of 400 nm, delivering 14 mW of optical power with a quantum efficiency of 5.4% and power conversion efficiency of 13%. Leveraging the electrical conductivity of the CQD stacks, further, the first broadband SWIR-active LED is demonstrated, paving the way toward complementary metal-oxide-semiconductor integrated broadband emitters for on-chip spectrometers and low-cost volume manufacturing. SWIR spectroscopy is employed to illustrate the practical relevance of the emitters in food and material identification case studies.
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Self-trapped excitons in two-dimensional perovskites. FRONTIERS OF OPTOELECTRONICS 2020; 13:225-234. [PMID: 36641579 PMCID: PMC9743880 DOI: 10.1007/s12200-020-1051-x] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/26/2020] [Accepted: 07/08/2020] [Indexed: 05/25/2023]
Abstract
With strong electron-phonon coupling, the self-trapped excitons are usually formed in materials, which leads to the local lattice distortion and localized excitons. The self-trapping strongly depends on the dimensionality of the materials. In the three-dimensional case, there is a potential barrier for self-trapping, whereas no such barrier is present for quasi-one-dimensional systems. Two-dimensional (2D) systems are marginal cases with a much lower potential barrier or nonexistent potential barrier for the self-trapping, leading to the easier formation of self-trapped states. Self-trapped excitons emission exhibits a broadband emission with a large Stokes shift below the bandgap. 2D perovskites are a class of layered structure material with unique optical properties and would find potential promising optoelectronic. In particular, self-trapped excitons are present in 2D perovskites and can significantly influence the optical and electrical properties of 2D perovskites due to the soft characteristic and strong electron-phonon interaction. Here, we summarized the luminescence characteristics, origins, and characterizations of self-trapped excitons in 2D perovskites and finally gave an introduction to their applications in optoelectronics.
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Structure-Dependent Photoluminescence in Low-Dimensional Ethylammonium, Propylammonium, and Butylammonium Lead Iodide Perovskites. ACS APPLIED MATERIALS & INTERFACES 2020; 12:5008-5016. [PMID: 31888331 DOI: 10.1021/acsami.9b17881] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Hybrid organic-inorganic perovskites have attracted great attention as the next generation materials for photovoltaic and light-emitting devices. However, their environment instability issue remains as the largest challenge for practical applications. Recently emerging two-dimensional (2D) perovskites with Ruddlesden-Popper structures are found to greatly improve the stability and aging problems. Furthermore, strong confinement of excitons in these natural quantum-well structures results in the distinct and narrow light emission in the visible spectral range, enabling the development of spectrally tunable light sources. Besides the strong quasi-monochromatic emission, some 2D perovskites composed of the specific organic cations and inorganic layer structures emit a pronounced broadband emission. Herein, we report the light-emitting properties and the degradation of low-dimensional perovskites consisting of the three shortest alkylammonium spacers, mono-ethylammonium (EA), n-propylammonium (PA), and n-butylammonium (BA). While (BA)2PbI4 is known to form well-oriented 2D thin films consisting of layers of corner-sharing PbI6 octahedra separated by a bilayer of BA cations, EA with shorter alkyl chains tends to form other types of lower-dimensional structures. Nevertheless, optical absorption edges of as-prepared fresh EAPbI3, (PA)2PbI4, and (BA)2PbI4 are obviously blue-shifted to 2.4-2.5 eV compared to their 3D counterpart, methylammonium lead iodide (MAPbI3) perovskite, and they all emit narrow excitonic photoluminescence. Furthermore, by carefully optimizing deposition conditions, we have achieved a predominantly 2D structure for (PA)2PbI4. However, unlike (BA)2PbI4, upon exposure to ambient environment, (PA)2PbI4 readily transforms to a different crystal structure, exhibiting a prominently broadband light from ∼500 to 800 nm and a gradual increase in intensity as structural transformation proceeds.
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Intrinsic White-Light-Emitting Metal-Organic Frameworks with Structurally Deformable Secondary Building Units. Angew Chem Int Ed Engl 2019; 58:7818-7822. [PMID: 30957350 DOI: 10.1002/anie.201903665] [Citation(s) in RCA: 46] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2019] [Indexed: 11/07/2022]
Abstract
The secondary building units in metal-organic frameworks (MOFs) are commonly well-defined metal-oxo clusters or chains with very limited structural strain. Herein, the structurally deformable haloplumbate units that are often observed in organolead halide perovskites have been successfully incorporated into MOFs. The resultant materials are a rare class of isoreticular MOFs exhibiting large Stokes-shifted broadband white-light emission, which is probably induced by self-trapped excitons from electron-phonon coupling in the deformable, zigzag [Pb2 X3 ]+ (X=Cl, Br, or I) chains. In contrast, MOFs with highly symmetric, robust haloplumbate chains only exhibit narrow UV-blue photoemission. The designed MOF-based intrinsic white-light photoemitters have a number of advantages over hybrid inorganic-organic perovskites in terms of stability and tunability, including moisture resistance, facile functionalization of photoactive moieties onto the organic linkers, introduction of luminescent guests.
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Pressure-Induced Broadband Emission of 2D Organic-Inorganic Hybrid Perovskite (C 6H 5C 2H 4NH 3) 2PbBr 4. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2019; 6:1801628. [PMID: 30693191 PMCID: PMC6343061 DOI: 10.1002/advs.201801628] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/18/2018] [Revised: 11/02/2018] [Indexed: 05/07/2023]
Abstract
2D Ruddlesden-Popper halide perovskites, which incorporate hydrophobic organic interlayers to considerably improve environmental stability and optical properties diversity, have attracted substantial research attention for optoelectronic applications. The burgeoning broad emission arising from exciton self-trapping of 2D perovskites shows a strong dependence on a deformable structure. Here, the pressure-induced broadband emission of layered (001) Pb-Br perovskite with a large Stokes shift in the visible region is observed by finely improving lattice distortion to increase exciton-phonon coupling under hydrostatic pressure. Band gap narrows ≈0.5 eV under modest pressure, mainly due to the large compressibility of the orientational organic layer, confirming that the bulky organic cations notably influence the structure and, in turn, the various properties of materials. Sequential amorphization of the organic and inorganic layer is confirmed by high pressure Raman and X-ray diffraction measurements, suggesting the particularity of layered crystal structures. The mechanism constructed here offers a new route for tuning the optical properties of 2D perovskites.
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Organic-Inorganic Layered and Hollow Tin Bromide Perovskite with Tunable Broadband Emission. ACS APPLIED MATERIALS & INTERFACES 2018; 10:34363-34369. [PMID: 30192511 DOI: 10.1021/acsami.8b07673] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Recently, layered perovskites attracted great attention for its excellent stability and light-emitting property. However, most of them rely on the toxic element lead and their emission quantum yields are generally low. Here, a unique hollow two-dimensional perovskite was developed in which the organic hexamethylene diamines (C6H18N22+) strongly coupled with distorted tin bromide anions (SnBr64-). This toxic-free low-dimensional tin perovskite exhibits a broadband emission in the visible region with a high luminescence quantum yield of 86%. First-principles calculation indicate the broadband emission is associated with the recombination of self-trapped excitons. And the emission is related to the geometry of tin bromide anions. An ultraviolet light-pumped white light emitting diode with excellent color-rendering index of 94 was fabricated using it together with a commercially available blue phosphor.
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