Harnessing solid-state ion exchange for the environmentally benign synthesis of high-efficiency Mn4+-doped phosphors

In this study, a solid-state ion exchange (SSIE) method is proposed to synthesize a series of Mn4+-doped fluoride phosphors, which avoids the use of HF solution during the Mn4+-doping process. The obtained Mn4+-doped fluoride phosphors exhibit strong red emission with a quantum yield of 46%.

Design Rules for Obtaining Narrow Luminescence from Semiconductors Made in Solution

Solution-processed semiconductors are in demand for present and next-generation optoelectronic technologies ranging from displays to quantum light sources because of their scalability and ease of integration into devices with diverse form factors. One of the central requirements for semiconductors used in these applications is a narrow photoluminescence (PL) line width. Narrow emission line widths are needed to ensure both color and single-photon purity, raising the question of what design rules are needed to obtain narrow emission from semiconductors made in solution. In this review, we first examine the requirements for colloidal emitters for a variety of applications including light-emitting diodes, photodetectors, lasers, and quantum information science. Next, we will delve into the sources of spectral broadening, including "homogeneous" broadening from dynamical broadening mechanisms in single-particle spectra, heterogeneous broadening from static structural differences in ensemble spectra, and spectral diffusion. Then, we compare the current state of the art in terms of emission line width for a variety of colloidal materials including II-VI quantum dots (QDs) and nanoplatelets, III-V QDs, alloyed QDs, metal-halide perovskites including nanocrystals and 2D structures, doped nanocrystals, and, finally, as a point of comparison, organic molecules. We end with some conclusions and connections, including an outline of promising paths forward.

Chemical coupling of halide perovskite nanocrystals with a metal quinolate complex for white light generation

Herein we report the construction of a white light emitting (WLE) nanocomposite by chemically coupling halide perovskite nanocrystals (HPNCs; e.g., orange-emitting Mn²⁺-doped CsPbCl₃) with a metal quinolate complex (e.g., a cyan-emitting calcium quinolate (CaQ₂) complex) while keeping their distinct features. The surface chloride of HPNCs coupled with the Ca-metal center of the CaQ₂ complex without altering the morphology, size, and dopant oxidation state of the HPNCs and provided additional environmental stability of the WLE nanocomposite. The photostable solid WLE nanocomposite displays chromaticity of (0.33, 0.32), color rendering index (CRI) of 80, correlated color temperature (CCT) of 5483 K, and quantum yield of 54.1%. This clearly indicates their bright WLE nature with properties close to those of bright midday sunlight. The current work will bring new surface chemistry between HPNCs and inorganic complexes and new paradigm toward advanced light emitting applications.

Single-Component White Light Emission from a Metal-Coordinated Cyclotriveratrylene-Based Coordination Polymer

A coordination polymer, namely, [Cd₃L(H₂O)₃]·DMA·4H₂O (1) (DMA = N,N-dimethylacetamide), was prepared by the solvothermal reaction of cyclotriveratrylene-based ligand 5,6,12,13,19,20-hexacarboxy-methoxy-cyclotriveratrylene (H₆L) and Cd(NO₃)₂·4H₂O. In 1, a two-dimensional structure was constructed by the connection of hexanuclear Cd-O clusters and L^6- anions. Photoluminescence measurements indicated that 1 displayed tunable photoluminescence through the variation of the excitation wavelength. Significantly, the white light emission of 1 can be observed with a broad excitation wavelength range from 320 to 385 nm. When 1 is excited by 385 nm light, its chromatic coordinate is (0.29, 0.34), which is located very close to the pure white light region (0.33, 0.33). Meanwhile, the color temperature (CCT) is 7994 K, which corresponds well to "cold" white light.

In situ preparation of Mn-doped perovskite nanocrystalline films and application to white light emitting devices

Mn-doped perovskite nanocrystals have promised new optoelectronic applications due to their unique material properties. In the present study, Mn-doped perovskite nanocrystalline films were prepared in situ in a polymer matrix. The Mn-doped perovskite nanocrystals (PNCs) had good crystallinity and uniform size/spatial distributions in the polymer film. Bright dual-color emission and the long lifetime of the excited state of the dopant were observed from the host exciton and the Mn²⁺ dopant, respectively. Furthermore, magnetism was observed in the optimal Mn²⁺ concentration, implying that magnetic coupling was achieved in the Mn-doped perovskite lattice. The Mn-doped perovskite films also showed superior stability against moisture. To demonstrate the practicality of this composite film, a white light emitting device was fabricated by combining a single composite film with a blue light emitting diode; the device showed a high-quality white light emission, and the Commission Internationale De L'Eclairage (CIE) chromaticity coordinate of the white light emitting diode (WLED) (0.361, 0.326) was close to the optimal white color index. In this single-layer WLED, self-absorption among the luminous multilayers in traditional white light emitting diodes can be avoided. The study findings revealed that Mn-doped perovskite nanocrystalline films have many exciting properties, which bodes well for the fundamental study and design of high-performance optoelectronic devices.

Encapsulation of perovskite quantum dots into LnIII-incorporated polymer matrix to achieve white light emission

All-inorganic perovskite quantum dots (PQDs) with high quantum efficiency and broad spectral tunability showing potential applications in light-emitting diodes (LEDs) are promising luminescent materials. However, poor stability has also become...

Highly Efficient Broadband White-light Emission in Two-dimensional Semi-conductive Hybrid Lead–Chlorine Halide

White-light emission (WLE) materials based on organic-inorganic hybrid Lead halides have drawn considerable attentions, because of its applications in light-emission equipments. Despite considerable efforts, there is still a lack of...

A review on two-dimensional (2D) perovskite material-based solar cells to enhance the power conversion efficiency

With perovskite materials, rapid progress in power conversion efficiency (PCE) to reach 25% has gained a significant amount of attention from the solar cell industry. Since the development of solid-state perovskite solar cells, rapid research development and investigation on structure design, device fabrication and fundamental studies have contributed to solid-state perovskite solar cells to be a strong candidate for next-generation solar energy. The promising efficiency with low-cost materials is the key point over the other material-based solar cells. The power conversion efficiency (PCE) of two-dimensional (2D) perovskite materials is yet to be enhanced in order to contest with the 3D perovskite-based solar cells. Their enormous variety compromises better prospects and possibilities for research. Two-dimensional (2D) perovskites play a multi-functional role within a solar cell, such as a capping layer, passivating layer, prime cell absorber, and in a hybrid 3D/2D perovskite-based solar cell absorber. This review summarizes the evolution of solar cells that are based on 2D perovskites and their prominent character in solar cells, along with the significant trends. The fundamental configuration and the optoelectronic characteristics, including the band orientation and the transportation of the charges, are discussed in detail. The 2D perovskites are analyzed to study the confined charges within the inorganic structure due to the dielectric and quantum confinement influence. Furthermore, the importance of cesium cation (Cs⁺) doped with 2D substance (BA)₂(MA₃) PbI₃ approach has been discussed to attain high power conversion efficiency (PCE). These attributes offer an efficient step towards air-stable and small-sized perovskites as a new group of renewable energy sources.

Multi-Dopant Engineering in Perovskite Cs2SnCl6: White Light Emitter and Spatially Luminescent Heterostructure

Bi³⁺/Te⁴⁺ co-doped Cs₂SnCl₆ with dual emission spectrum (i.e., 450 and 575 nm) was achieved by a modified solution method, which can overcome the phase separation in the previous method for Cs₂SnCl₆ crystal growth. The two emission peaks arising from the two dopants Bi³⁺ and Te⁴⁺ have distinct photoluminescence (PL) lifetimes. Thus, the control of dopant ratio or PL delay time will regulate the PL intensity ratio between 450 and 575 nm peaks leading to adjustable emission color. The energy transfer between the two emission centers, which is confirmed by the optical spectra and PL lifetime, has a critical distance around 7.8 nm with a maximum of 50% transfer efficiency. The Bi³⁺/Te⁴⁺ co-doped Cs₂SnCl₆ with superior stability in water and aqua regia was fabricated into a single-phase white light-emitting diode. In the meantime, various luminescent heterostructures were obtained by epitaxial Cs₂SnCl₆ crystal growth with different dopants, which can broaden the study of composition engineering in halide perovskites.

Switchable Anion Exchange in Polymer-Encapsulated APbX3 Nanocrystals Delivers Stable All-Perovskite White Emitters

We report a one-step synthesis of halide perovskite nanocrystals embedded in amphiphilic polymer (poly(acrylic acid)-block-poly(styrene), PAA-b-PS) micelles, based on injecting a dimethylformamide solution of PAA-b-PS, PbBr₂, ABr (A = Cs, formamidinium, or both) and "additive" molecules in toluene. These bifunctional or trifunctional short chain organic molecules improve the nanocrystal-polymer compatibility, increasing the nanocrystal stability against polar solvents and high flux irradiation (the nanocrystals retain almost 80% of their photoluminescence after 1 h of 3.2 w/cm² irradiation). If the nanocrystals are suspended in toluene, the coil state of the polymer allows the nanocrystals to undergo halide exchange, enabling emission color tunability. If the nanocrystals are suspended in methanol, or dried as powders, the polymer is in the globule state, and they are inert to halide exchange. By mixing three primary colors we could prepare stable, multicolor emissive samples (for example, white emitting powders) and a UV-to-white color converting layer for light-emitting diodes entirely made of perovskite nanocrystals.

One-dimensional lead iodide hybrid stabilized by inorganic hexarhenium cluster cations as a new broad-band emitter

A novel one-dimensional (1D) hybrid {[Re₆S₈(PzH)₆][Pb₃I₈(DMF)₂]}·6(DMF) with hexarhenium cluster cations has been synthesized and characterized by means of single-crystal X-ray diffraction. Two DMF oxygen atoms bridge three lead iodides to form a set of lead iodides, {[PbI_4/2I(O_DMF)_1/2][PbI_4/2(O_DMF)_2/2][PbI_4/2I(O_DMF)_1/2]}²⁻, and these sets of lead iodide share edges to form a 1D lead iodide chain, [Pb₃I₈(DMF)₂]²⁻ which has never been reported before and is different from the typical edge sharing of octahedral PbI₆ units. 1D lead iodide chains are stacked along the a axis, and [Re₆S₈(PzH)₆]²⁺ cations with H-bonded DMF molecules to pyrazole N–H reside between 1D lead iodide chains. This 1D lead iodide hybrid shows strong broad-band emission with a peak at 634 nm. The excellent photoluminescent properties of the new lead iodide hybrid exhibit great potential for optoelectronic applications in photonic devices with broad-band emission and stability. This study introduces a new class of lead iodide hybrid compounds having new inorganic cluster cations rather than the organic amine cations that have been used in numerous studies to date. This work opens a promising path to overcome the instability of perovskites including of organic amine cations.

A novel one-dimensional (1D) hybrid {[Re₆S₈(Pz)₆][Pb₃I₈(DMF)₂]}·6(DMF) with hexarhenium cluster cations has been synthesized, and it shows strong broad-band emission with peak at 634 nm.

Halide Perovskites: A New Era of Solution-Processed Electronics

Organic-inorganic mixed halide perovskites have emerged as an excellent class of materials with a unique combination of optoelectronic properties, suitable for a plethora of applications ranging from solar cells to light-emitting diodes and photoelectrochemical devices. Recent works have showcased hybrid perovskites for electronic applications through improvements in materials design, processing, and device stability. Herein, a comprehensive up-to-date review is presented on hybrid perovskite electronics with a focus on transistors and memories. These applications are supported by the fundamental material properties of hybrid perovskite semiconductors such as tunable bandgap, ambipolar charge transport, reasonable mobility, defect characteristics, and solution processability, which are highlighted first. Then, recent progresses on perovskite-based transistors are reviewed, covering aspects of fabrication process, patterning techniques, contact engineering, 2D versus 3D material selection, and device performance. Furthermore, applications of perovskites in nonvolatile memories and artificial synaptic devices are presented. The ambient instability of hybrid perovskites and the strategies to tackle this bottleneck are also discussed. Finally, an outlook and opportunities to develop perovskite-based electronics as a competitive and feasible technology are highlighted.

In Situ Ambient Preparation of Perovskite-Poly(l-lactic acid) Phosphors for Highly Stable and Efficient Hybrid Light-Emitting Diodes

Metal halide perovskite (MHP)-based phosphor-converted light-emitting diodes (pc-LEDs) are limited by the low MHP stability under storage/operation conditions. A few works have recently established the in situ synthesis of MHPs into polymer matrices as an effective strategy to enhance the stability of MHP with a low-cost fabrication. However, this is limited to petrochemical-based polymers. Herein, the first in situ ambient preparation of highly luminescent and stable MHP-biopolymer filters (MAPbBr₃ nanocrystals as an emitter and poly(l-lactic acid) (PLLA) as the matrix) with arbitrary areas (up to ca. 300 cm²) is reported. The MAPbBr₃-PLLA phosphors feature a narrow emission (25 nm) with excellent photoluminescence quantum yields (>85%) and stability under ambient storage, water, and thermal stress. This is corroborated in green pc-LEDs featuring a low-efficiency roll-off, an excellent operational stability of ca. 600 h, and high luminous efficiencies of 65 lm W^-1 that stand out compared to the prior state of the art (e.g., an average lifetime of 200 h at 50 lm W^-1). The filters are further exploited to fabricate white-emitting pc-LEDs with efficiencies of ca. 73 lm W^-1 and x/y CIE color coordinates of 0.33/0.32. Overall, this work establishes a straightforward (one-pot/in situ) and low-cost preparation (ambient/room temperature) of highly efficient and stable MHP-biopolymer phosphors for highly performing and more sustainable lighting devices.

Low-Toxicity Perovskite Applications in Carbon Electrode Perovskite Solar Cells—A Review

Perovskite solar cells (PSCs) with earth-abundant carbon as an effective replacer for unstable hole-transporting materials and expensive electrodes is a recently proposed structure promising better air and moisture stability. In this review paper, we report on the latest advances and state of the art of Pb-free and low-Pb-content perovskites, used as absorbers in carbon-based perovskite solar cells. The focus is on the implementation of these, environmentally friendly and non-toxic, structures in PSCs with a carbon electrode as a replacement of the noble metal electrode typically used (C-PSCs). The motivation for this study has been the great potential that C-PSCs have shown for the leap towards the commercialization of PSCs. Some of their outstanding properties include low cost, high-stability, ambient processability and compatibility with most up-scaling methods (e.g., printing). By surpassing the key obstacle of toxicity, caused by the Pb content of the highest-performing perovskites, and by combining the advantages of C-PSCs with the Pb-free perovskites low toxicity, this technology will move one step further; this review summarizes the most promising routes that have been reported so far towards that direction.

Synthesis, Study, and Application of Pd(II) Hydrazone Complexes as the Emissive Components of Single-Layer Light-Emitting Electrochemical Cells

For the first time, square planar Pd(II) complexes of hydrazone ligands have been investigated as the emissive components of light-emitting electrochemical cells (LECs). The neutral transition metal complex, [Pd(L¹)₂]·2CH₃OH (1), (HL¹ = (E)-N'-(phenyl(pyridin-2-yl)methylene)isonicotinhydrazide), was prepared and structurally characterized. Complex 1 displays quasireversible redox properties and is emissive at room temperature in solution with a λ_max of 590 nm. As a result, it was subsequently employed as the emissive material of a single-layer LEC with configuration FTO/1/Ga/In, where studies reveal that it has a yellow color with CIE(x, y) = (0.33, 0.55), a luminance of 134 cd cm^-2, and a turn-on voltage of 3.5 V. Protonation of the pendant pyridine nitrogen atoms of L¹ afforded a second ionic complex [Pd(L¹H)₂](ClO₄)₂ (2) which is also emissive at room temperature with a λ_max of 611 nm, resulting in an orange LEC with CIE(x, y) = (0.43, 0.53). The presence of mobile anions and cations in the second inorganic transition metal complex resulted in more efficient charge injection and transport which significantly improved the luminance and turn-on voltage of the device to 188.6 cd cm^-2 and 3 V, respectively. This study establishes Pd(II) hydrazone complexes as a new class of materials whose emissive properties can be chemically tuned and provides proof-of-concept for their use in LECs, opening up exciting new avenues for potential applications in the field of solid state lighting.

(γ-Methoxy propyl amine)2PbBr4: a novel two-dimensional halide hybrid perovskite with efficient bluish white-light emission

A 2D hybrid perovskite based on alkoxyamine cations shows bright bluish white-light emission with a high PLQE of 6.85%.

High Color-Rendering Index and Stable White Light-Emitting Diodes by Assembling Two Broadband Emissive Self-Trapped Excitons

White light-emitting diodes (WLEDs) are promising next-generation solid-state light sources. However, the commercialization route for WLED production suffers from challenges in terms of insufficient color-rendering index (CRI), color instability, and incorporation of rare-earth elements. Herein, a new two-component strategy is developed by assembling two broadband emissive materials with self-trapped excitons (STEs) for high CRI and stable WLEDs. The strategy addresses effectively the challenging issues facing current WLEDs. Based on first-principles thermodynamic calculations, copper-based ternary halides composites, CsCu₂ I₃ @Cs₃ Cu₂ I₅ , are synthesized by a facile one-step solution approach. The composites exhibit an ideal white-light emission with a cold/warm white-light tuning and a robust stability against heat, ultraviolet light, and environmental oxygen/moisture. A series of cold/warm tunable WLEDs is demonstrated with a maximum luminance of 145 cd m^-2 and an external quantum efficiency of 0.15%, and a record high CRI of 91.6 is achieved, which is the highest value for lead-free WLEDs. Importantly, the fabricated device demonstrates an excellent operation stability in a continuous current mode, exhibiting a long half-lifetime of 238.5 min. The results promise the use of the hybrids of STEs-derived broadband emissive materials for high-performance WLEDs.

Lead-Free Metal Halide Perovskites and Perovskite Derivatives as an Environmentally Friendly Emitter for Light-Emitting Device Applications

Recently, newly emerging lead halide perovskites have attracted great attention as a new class of light emitters in luminescent devices because of their superior photoluminescence quantum yield, adjustable emission wavelength, high charge-carrier transport ability, and low-temperature processing technique. However, the poor stability and lead toxicity of such materials severely restrict their practical applications and future commercialization. Therefore, recent efforts have been devoted to developing lead-free metal halide perovskites and their derivatives to address the above hurdles. In this Perspective, we first review the recent progress on the lead-free metal halide materials and their optical properties. We then discuss the stability issues of lead-free perovskites against heat, ultraviolet light, oxygen, and moisture. Further, we give a demonstration of the preliminary achievements and limitations in lead-free material-based light-emitting devices. Finally, we present current existing challenges and possible development opportunities in this field based on lead-free material systems.

Pressure Effects on the Electronic and Optical Properties in Low-Dimensional Metal Halide Perovskites

Metal halide perovskites have shown enormous potential in perovskite solar cells and light-emitting diodes and made unprecedented progress in the past decade. Pressure engineering as an effective technique can systematically modify the electronic structures and physical properties of functional materials. Low-dimensional metal halide perovskites (0D, 1D, and 2D) with a variety of compositions have soft lattices that allow pressure to drastically modulate their structures and properties. High-pressure investigations have obtained a comprehensive understanding of their structure-property relationships. Simultaneously, discoveries of novel pressure-driven properties, such as metallization and partially retained band gap narrowing have contributed significantly to the further development of such materials. In this Perspective, we mainly highlight the effect of pressure on the properties and structures of low-dimensional metal halide perovskites, which is essential for designing new perovskite materials and advancing applications.

Stable white photoluminescence from Mn-contained organic lead bromide perovskite ring arrays formed from 2D colloidal crystal templates

C₄N₂H₁₄Pb_xMn_1−xBr₄ perovskite ring arrays with stable white light emission and controllable size for high color quality white light-emitting diodes.

A hybrid blue perovskite@metal-organic gel (MOG) nanocomposite: simultaneous improvement of luminescence and stability

Blue light-emitting hybrid perovskite nanocrystals (NCs) are promising candidates for optoelectronic applications. However, these NCs suffer severely from low photoluminescence quantum yield (PLQY) and inferior stability under working conditions. Herein, we report, for the first time, a simultaneous dramatic improvement in both the luminescence and the stability of hybrid perovskite NCs through embedding in a porous metal-organic gel (MOG) matrix. The nanocomposite (EAPbBr3@MOG, EA: ethylammonium) shows sharp emission in the intense blue region (λ max < 440 nm), with a substantial ten-fold enhancement in the PLQY (∼53%) compared with EAPbBr3 NCs (PLQY ∼5%). Incorporation of perovskite NCs into the soft MOG matrix provides the additional benefits of flexibility as well as water stability. As a proof of principle, these nanocomposites were further utilized to fabricate a white light-emitting diode. The combination of high brightness, stability and flexibility of these nanocomposites could render them viable contenders in the development of efficient, blue light-emitting diodes for practical applications.

Energy transfer-mediated white light emission from Nile red-doped 9,10-diphenylanthracene nanoaggregates upon excitation with near UV light

The low cost, ease of preparation, colour tunability and wide application range garnered huge research interest on organic light emitting diode materials (OLED). The development of white light-emitting organic diode materials is mostly targeted for this. Anthracene derivatives have recently emerged as low-cost and efficient blue light-emitting diodes. However, developing efficient organic diode materials that cover the entire visible spectrum is very challenging. Herein, we demonstrated that Nile red (NR)-doped 9,10-diphenylanthracene (DPA) nanoaggregates provided strong white light emission upon excitation with near UV light. The dual emissions of the DPA nanoaggregates covering the blue and green regions were exploited and combined with the controlled red emission of the properly doped NR dye to cover the full visible spectrum, rendering white light emission with a quantum yield of >0.4. The fluorescence spectra of the DPA nanoaggregates doped with NR at various concentrations were monitored and their CIE coordinates were followed to evaluate the proper doping ratio for equal-energy white-light emission. Concurrent time-resolved emission studies provided mechanistic insights into the energy transfer from the exciton and excimer states of DPA to NR. It was revealed that the energy transfer from the singlet excitonic state of DPA followed the diffusion-assisted resonance energy transfer (RET) model. On the other hand, the excimer state showed negligible diffusion and energy transfer from this state found to follow the single-step Förster resonance energy transfer mechanism. The observation of efficient white light emission in the doped DPA nanoaggregates was proposed to have prospective applications in OLED devices, given the fact that triplet excitons may be exploited for emission through the efficient triplet-triplet annihilation contribution to fluorescence enhancement.

White light emitting diode based on purely organic fluorescent to modern thermally activated delayed fluorescence (TADF) and perovskite materials

White organic/polymer light emitting diode (WOLED/WPLED) processed from solution has attracted significant research interest in recent years due to their low device production cost, device flexibility, easy fabrication over large area including roll to roll and ability to print in various designs and shapes providing enormous design possibilities. Although WOLEDs fabricated using solution process lack their thermally evaporated counterparts in terms of device efficiency, remarkable progress has been made in this regard in recent years by utilizing new materials and device structures. In the present review, we have summarized and extrapolated an excellent association of old and modern concept of cost-effective materials and device structure for realization of white light. In particular, this article demonstrated and focused on design, and development of novel synthesis strategy, mechanistic insights and device engineering for solution process low cost WOLEDs device. Herein, an overview of the prevailing routes towards white light emitting devices (WLEDs) and corresponding materials used, including polymer based WLED, small molecules emitters based thermally activated delayed fluorescence (TADF), perovskite light-emitting diodes (PeLEDs) and hybrid materials based LEDs, color down-converting coatings with corresponding best efficiencies ever realized. We presume that this exhaustive review on WLEDs will offer a broad overview of the latest developments on white SSL and stonework the approach en route for innovations in the immediate future.

An overview on enhancing the stability of lead halide perovskite quantum dots and their applications in phosphor-converted LEDs

Beyond the unprecedented success achieved in photovoltaics (PVs), lead halide perovskites (LHPs) have shown great potential in other optoelectronic devices. Among them, nanometer-scale perovskite quantum dots (PQDs) with fascinating optical properties including high brightness, tunable emission wavelength, high color purity, and high defect tolerance have been regarded as promising alternative down-conversion materials in phosphor-converted light-emitting diodes (pc-LEDs) for lighting and next-generation of display technology. Despite the promising applications of perovskite materials in various fields, they have received strong criticism for the lack of stability. The poor stability has also attracted much attention. Within a few years, numerous strategies towards enhancing the stability have been developed. This review summarizes the mechanisms of intrinsic- and extrinsic-environment-induced decomposition of PQDs. Simultaneously, the strategies for improving the stability of PQDs are reviewed in detail, which can be classified into four types: (1) compositional engineering; (2) surface engineering; (3) matrix encapsulation; (4) device encapsulation. Finally, the challenges for applying PQDs in pc-LEDs are highlighted, and some possible solutions to improve the stability of PQDs together with suggestions for further improving the performance of pc-LEDs as well as the device lifetime are provided.

Room temperature growth of CH3NH3PbCl3 single crystals by solvent evaporation method

Rectangular shaped, high crystalline quality, defect free and colorless 3D perovskite single crystals of CH₃NH₃PbCl₃ were grown using the solvent evaporation method at room temperature for the first time.

Ultrastable Luminescent Organic-Inorganic Perovskite Quantum Dots via Surface Engineering: Coordination of Methylammonium Bromide and Covalent Silica Encapsulation

Encapsulation of luminescent perovskite quantum dots (QDs) into a solid matrix has been approved to be an efficient way to improve their stability. In this work, we reported a green encapsulation method to produce ultrastable CH₃NH₃PbBr₃ QDs incorporated into the SiO₂ matrix. Specifically, fresh-prepared CH₃NH₃PbBr₃ QDs were covalently embedded into silica by an aqueous sol-gel method assisted with CH₃NH₃Br, which not only effectively inhibited the water-driven degradation of QDs through surface coordination, but also strongly stabilized the QDs in solid powder via concentration gradient. As far as we know, this silica encapsulation of perovskite QDs in aqueous environments is reported for the first time. Luminescent properties of perovskite QDs during the course of gelation as well as in resulting composite powder were investigated using steady-state and time-resolved spectroscopies, and a 2 wt % QD-doped sample treated with 11.5 mM of CH₃NH₃Br was demonstrated to be the optimal phosphor. The green-emissive phosphor had a PLQY of 60.3% and a full width at half maxima of ∼25 nm, exhibiting ultrahigh stability tested by cycle heating (120 °C), continuous heating (80 °C, 60 h), and light irradiation (450 nm light, 350 h). The phosphor was readily blended with polymers and applied as a color-converting layer on blue light-emitting diodes.

Single-Component Biohybrid Light-Emitting Diodes Using a White-Emitting Fused Protein

This work presents a pioneering multidisciplinary approach toward enhancing biohybrid light-emitting diodes (BioHLEDs), merging synthetic biology tools, polymer chemistry, and device engineering to design a thin color down-converting coating with a single white-emitting fluorescent protein (WFP). In particular, the WFP consists of fused red-, green-, and blue-emitting FPs following the so-called protein superglue approach. This WFP shows an efficient and stable white emission originated from a Förster resonance energy transfer between FP moieties. The emission chromaticity is, in addition, easily controlled by the rigidity of the polymer matrix of the coating, reaching photoluminescence quantum yields of 26% that stand out among intrinsic white-emitting materials. The WFP single-component color down-converting packaging was applied to fabricate BioHLEDs featuring efficient neutral white emission that is stable over 400 h. This represents the most stable BioHLED reported to date. Thus, this work is a landmark for the use of synthetic biology tools to design tailored luminescent biomaterials for lighting applications.