Emission Efficiency Research Articles

How does China’s Winter Heating policy impact corporate sustainable development performance?

The China’s Winter Heating policy plays a crucial role in China’s regional environmental regulatory framework, particularly concerning the challenge of atmospheric pollution. This study investigates the impact of this policy on corporate sustainable development performance in the “2+26” cities of the Beijing, Tianjin and Hebei region (BTH2+26) at the micro-level. It employs a dual perspective focusing on emission reduction and efficiency enhancement (i.e., sustainable development), utilizing a DID model based on the policy shock from the first implementation of the China’s Winter Heating policy in 2017. The findings indicate that this policy not only effectively promotes pollution reduction among heavy-polluting companies, thereby enhancing their environmental performance, but also improves their financial performance. Robustness tests confirm the significance of these results. Mechanism analysis reveals that the policy’s facilitative effect on heavy-polluting companies is mediated through promoting green innovation and easing financing constraints, with the innovation investment being the main channel to promote the corporate environmental performance. Heterogeneity analysis shows differential impacts across company nature and industry attributes, highlighting the policy’s varied effects on environmental performance and financial performance across sectors. This research contributes empirical evidence and policy insights into enhancing sustainable development performance among heavy-polluting companies under the China’s Winter Heating policy framework.

An Experimental Investigation of 1,2-dimethoxy ethane as a Fuel Additive in Biodiesel-Fueled Diesel Engine

Recently, researchers have focused on the addition of various additives to biodiesel and other petroleum-derived fuels to improve combustion characteristics and reduce pollutant emissions in internal combustion engines. This study explores the effects of integrating 1,2-dimethoxy ethane (1,2-DME) into reference fuels (RF), including 100% diesel (D100), 100% biodiesel (B100), and a blend of 50% diesel with 50% biodiesel (B50). In the experiment, 1,2-DME is added at volumes of 5%, 10%, and 15% while engine load is at 25%, 50%, and 75%. In-cylinder pressure and temperature, heat release rate (HRR), knock intensity (RI), combustion duration (CD), ignition delay (ID), brake thermal efficiency (BTE) and pollutant emissions such as carbon monoxide (CO), nitrogen oxides (NOx), hydrocarbon (HC), and smoke opacity are all evaluated. The findings reveal that increasing the 1,2-DME ratio in the reference fuels enhances HRR, in-cylinder pressure, and temperature. Notably, adding 10% 1,2-DME to D100 at 25% engine load significantly increases HRR by approximately 28.65%. Generally, incorporating 1,2-DME reduces ignition delay, shortens ignition duration and intensifies knock (RI). Analysis of pollutant emissions indicates an increase in nitrogen oxide (NOx) emissions but a reductions in carbon monoxide (CO) and hydrocarbon (HC) emissions with 1,2-DME addition. Furthermore, adding 15% 1,2-DME to D100 at 25% engine load reduces smoke opacity by 59.2%. In summary, the significant effects of 1,2-DME on reference fuels indicate its potential as a viable alternative fuel additive.

Timescales distribution and reactive structures in MILD reactors for different energy carriers

Moderate or Intense Low-oxygen Dilution (MILD) combustion processes are purported to be fuel-flexible, thus offering a real opportunity to use a large palette of fuels. In this respect, the way the oxidative reactive structure may change by changing the specific fuel is a key issue to determine, to continue relying on high efficiency and low pollutant emissions of MILD combustion. In this work, the differences among the reactive structures at the macroscale of the MILD process were analyzed for pure NH3, CH4 and H2, with a peculiar attention to the interplay between chemical (τc) and turbulence (τI) timescales. Reactive structures were analyzed through a combined experimental and CFD approach. To this purpose, a cyclonic MILD burner was considered as reference experimental facility, while macroscale features were resolved through CFD simulations using the Partially Stirred Reactor (PaSR) model. Results were analyzed in terms of Heat Release, reactive cell number distribution and behavior. Experimental results highlighted the existence of a distributed reactive region for the cyclonic burner, independently of the considered fuel, while its spatial distribution and extension were found to be significantly affected by the fuel reactivity. As the fuel reactivity increases, reactive regions tighten and move upstream the burner exit. This results in a uniform heat release region for pure NH3 and more localized areas for H2, while CH4 shows and intermediate behavior. Furthermore, the chemical and fluid-dynamic timescales interplay covers a fundamental role in defining the global behavior of reactive regions. These approach a PSR-like condition as the fuel reactivity decreases (NH3<CH4<H2), as result of the longer chemical times compared to the mixing ones (τc>>τI).

Influence of silica fume on pore structure, mechanical properties and carbon emission of reactive powder concrete prepared by ice crystal homogenization technology

Under ultra-low water-to-binder ratio conditions, the liquid-bridge effect between powders seriously restricts the development of reactive powder concrete (RPC). Ice crystal homogenization technology fundamentally solves the liquid-bridge problem between powders. However, high carbon emissions still constrain the application of RPC. This paper introduces an innovative RPC material incorporating silica fume (SF) as a supplementary cementitious material to solve environmental concerns and alleviate powder aggregation challenges based on the ice crystal homogenization technology. Experimental results show that there was a significant improvement in compressive and flexural strengths observed, particularly in RPC material containing 15% SF, which exhibited the most notable enhancements: a 19.7% increase in compressive strength to 296.3MPa and a 23.6% increase in flexural strength to 43.8MPa. Moreover, the optimized microstructure was reflected in a substantial reduction in water absorption rate and cumulative pore volume by 44.7% and 54.4%, respectively. Besides, RPC incorporating 15% SF achieved the lowest carbon emissions efficiency, with carbon emissions efficiency could be reduced by 79%~93% compared with conventional UHPC. In conclusion, the use of SF and ice crystal homogenization technology in RPC provides the great potential for developing sustainable construction materials and promoting carbon reduction strategies.

Performance-optimized and phase purity-improved high-n quasi-two-dimensional perovskite for green light-emitting diodes

Quasi-two-dimensional (quasi-2D) perovskite has the advantage of enlarging exciton binding energy and is more suitable for efficient perovskite light-emitting diodes (PeLEDs). However, the quasi-2D perovskite films deposited with solution methods are usually mixtures of multiple phases with different inorganic layer numbers (n), unfavorable to obtaining high emission efficiency. In this study, we selected formamidinium lead bromide (FAPbBr3) as the light emitter and (2-phenylethyl)ammonium cation (PEA+) as the long-chain organic spacer cation to prepare high-n (n = 9) quasi-2D perovskite films with improved phase purity. Based on the multiple cations mixed engineering, the quality of these films improved obviously by partly replacing FA+ with minute quantities of cesium cation (Cs+). The improvement focused on remarkably enhanced photoluminescence, few low-n phases, and decreased grain sizes. The green PeLED based on the performance-optimized and phase purity-improved high-n quasi-2D perovskite reached a high brightness of 28 960 cd/m2 together with a maximum current efficiency of 44.8 cd/A and a maximum external quantum efficiency of 9.99%.

A Widely and Continuously Tunable Single-Mode Transmitter Based on a Hybrid Microcavity Laser

A method for achieving the single-mode and efficient unidirectional emission of a whispering gallery mode (WGM) semiconductor laser is presented herein. Hybrid square-rectangular lasers (HSRLs) and hybrid square/rhombus-rectangular lasers (HSRRLs) consisting of a Fabry–Pérot (FP) cavity and a square or rhombus cavity microcavity are described. In addition, a transmitter optical subassembly (TOSA) based on an HSRRL chip was fabricated, which has a wide and continuous wavelength tuning range. Wavelength channels from 1555.75 nm to 1568.15 nm with a spacing of 50 GHz were demonstrated with a good side mode suppression ratio (SMSR) and good output power. These devices have the potential to meet the typical requirements of optical communication networks.

Evaluating the Effects of Fertilizer Deep Placement on Greenhouse Gas Emissions and Nutrient Use Efficiency in Wet Direct-Seeded Rice During the Wet Season in Assam, India

Mitigation of greenhouse gases (GHGs), improving nutrient-use efficiency (NUE), and maximizing yield in rainfed lowland rice cultivation poses significant challenges. To address this, a two-year field experiment (2020 and 2021) was conducted in Assam, India, to examine the impact of different fertilizer-management practices on grain yield, NUE, and GHGs in wet direct-seeded rice (Wet-DSR) during the kharif season. The experiment included eight treatments: control; farmer’s practice (30-18.4-36 kg N-P2O5-K2O ha−1); state recommended dose of fertilizer (RDF) @ 60-20-40 kg N-P2O5-K2O ha−1 with N applied in three splits @ 30-15-15 kg ha−1 as basal, at active tillering (AT), and panicle initiation (PI); best fertilizer management practices (BMPs): 60-20-40 kg N-P2O5-K2O ha−1 with N applied in three equal splits as basal, at AT, and PI; and fertilizer deep placement (FDP) of 120%, 100%, 80%, and 60% N combined with 100% PK of RDF. The experiment was arranged out in a randomized complete block design with three replications for each treatment. The highest grain yield (4933 kg ha−1) and straw yield (6520 kg ha−1) were achieved with the deep placement of 120% N + 100% PK of RDF. FDP with 80% N + 100% PK reduced 38% N2O emissions compared to AAU’s RDF and BMPs, where fertilizer was broadcasted. This is mainly due to the lower dose of nitrogen fertilizer and the application of fertilizer in a reduced zone of soil. When considering both productivity and environmental impact, applying 80% N with 100% PK through FDP was identified as the most effective practice.

Diarenofuran[b]-fused BODIPYs: One-Pot SNAr-Suzuki Synthesis and Properties.

We present a streamlined methodology that integrates regioselective tetrahalogen-BODIPY and o-hydroxyphenylboronic acid in a one-pot process, leveraging SNAr nucleophilic substitution in conjunction with Suzuki coupling to afford diarenofuran [b]-fused BODIPYs (DBFB1-9) with commendable yields (85-95%) and short reaction times (0.5-1.0 h). X-ray structure analyses of DBFB5,7-9 elucidate that these diarenofuran[b]-fused BODIPYs adopt a "butterfly" conformation, maintaining a highly rigid planarity. A comprehensive examination of the spectroscopic and electrochemical properties of these diarenofuran[b]-fused BODIPY derivatives, incorporating various substituents, reveals intriguing characteristics, including pronounced absorption and emission in the near-infrared region (NIR), elevated fluorescence quantum yields (ΦF = 75-89% in dichloromethane), and tunable HOMO-LUMO levels. Remarkably, compared to DBFB1-8, DBFB9 possesses a large extended π-conjugated system, resulting in significant red shifts in its absorption and emission maxima, reaching 623 and 635 nm, respectively, and a reduced HOMO-LUMO gap. Despite this substantial structural expansion, DBFB9 maintains a surprisingly high fluorescence quantum yield (ΦF = 80%), underscoring its exceptional photophysical performance and strong potential for applications requiring efficient NIR emission and robust fluorescence retention.

Plasticizer Design Principle of "Like Dissolves Like": Semiconductor Fluid Plasticized Stretchable Fully π-Conjugated Polymers Films for Uniform Large-Area and Flexible Deep-Blue Polymer Light-Emitting Diodes.

Physical blending of fully π-conjugated polymers (FπCPs) is an effective strategy to achieve intrinsically stretchable films for the fabrication of flexible optoelectronic devices, but easily causes phase separation, nonuniform morphology and uncontrollable photo-electronic processing. This may cause low efficiency, unstable and nonuniform emission, and poor color purity, which are undesirable for deep-blue flexible polymer light-emitting diodes (FPLEDs). Herein, a "Like Dissolves Like" design principle to prepare semiconductor fluid plasticizers (SFPs) is established and intrinsically stretchable FπCPs films via external plasticization for high-performance deep-blue FPLEDs are developed. Three fundamental requirements are proposed, "similar conjugated skeleton, similar molecular polarity, and similar electronic structures," to prepare model-matched nonpolar M1 and polar M2 plasticizers for poly(9,9-dioctylfluorene) (PFO). Large-area plasticized PFO films exhibit an efficient, narrowband, and stable ultra-deep-blue electroluminescence (FWHM < 40nm, CIE: 0.12, 0.04), uniform morphology, and excellent intrinsic stretchability (fracture strain >20% and crack-onset strain >120%). Efficient and uniform deep-blue FPLEDs based on stretchable PFO films are fabricated with a high brightness of ≈3000cd cm-2. Finally, blended PFO films exhibit outstanding stretch-deformation cycling stability of their deep-blue electroluminescent behavior, confirming the effectiveness of the "Like Dissolves Like" principle to design matched SFPs for stretchable FπCP films in flexible electronics.

Cocrystallization‐Induced Red Ultralong Organic Phosphorescence

AbstractOrganic cocrystals formed through multicomponent self‐assembly have attracted significant interest owing to their clear structure and tunable optical properties. However, most cocrystal systems suffer from inefficient long‐wavelength emission and low phosphorescence efficiency due to strong non‐radiative processes governed by the energy gap law. Herein, an efficient long‐lived red afterglow is achieved using a pyrene (Py) cocrystal system incorporating a second component (NPYC4) with thermally activated delayed fluorescence (TADF) and ultralong organic phosphorescence (UOP) properties. The cocrystal (NPYC4‐Py) not only inherits the excellent luminescence of its monomeric counterparts, but also exhibits unique dual‐mode characteristics, including persistent TADF and UOP emission with a high quantum yield of 58 % and a lifetime of 362 ms. The precise cocrystal stacking distinctly reveals that intermolecular interactions lock the cocrystal formation and weaken the intermolecular π‐π interactions between NPYC4 and Py, thereby stabilizing the excited triplet excitons. Furthermore, the favorable energy level of NPYC4 acts as a bridge, reducing the energy gap between the S1 and T1 states for Py, therefore activating its red phosphorescence from Py. This research provides direct insights into achieving efficient red UOP through co‐crystallization.

Cocrystallization-Induced Red Ultralong Organic Phosphorescence.

Organic cocrystals formed through multicomponent self-assembly have attracted significant interest owing to their clear structure and tunable optical properties. However, most cocrystal systems suffer from inefficient long-wavelength emission and low phosphorescence efficiency due to strong non-radiative processes governed by the energy gap law. Herein, an efficient long-lived red afterglow is achieved using a pyrene (Py) cocrystal system incorporating a second component (NPYC4) with thermally activated delayed fluorescence (TADF) and ultralong organic phosphorescence (UOP) properties. The cocrystal (NPYC4-Py) not only inherits the excellent luminescence of its monomeric counterparts, but also exhibits unique dual-mode characteristics, including persistent TADF and UOP emission with a high quantum yield of 58 % and a lifetime of 362 ms. The precise cocrystal stacking distinctly reveals that intermolecular interactions lock the cocrystal formation and weaken the intermolecular π-π interactions between NPYC4 and Py, thereby stabilizing the excited triplet excitons. Furthermore, the favorable energy level of NPYC4 acts as a bridge, reducing the energy gap between the S1 and T1 states for Py, therefore activating its red phosphorescence from Py. This research provides direct insights into achieving efficient red UOP through co-crystallization.

De(sulfon)amidative Cyclization: The Synthesis of Dibenzolactams and Dibenzosultams for Organic Light Emitting Diode Materials

AbstractThis study addresses a challenge in organic synthetic chemistry: the direct cleavage of amide bonds, which is typically hampered by the thermodynamic stability of the C(Ar)−C(acyl) bond. Previous methods often rely on “CO” extrusion‐jointing transition metal‐catalyzed process and require activated tertiary amides, limiting their applicability due to incompatibility with reactive functional groups such as halogens. Herein, we report a transition metal‐free approach for the deamidative cyclization of biaryl diamides via a radical process, yielding dibenzolactam derivatives. Along this line, we have developed the desulfonamidative cyclization of biaryl disulfonamides to produce dibenzosultams through direct nucleophilic aromatic substitution, demonstrating high selectivity for unsymmetrical structures. Additionally, unsymmetrical sulfamoyl biaryl amides, containing both amide and sulfonamide functionalities, can selectively undergo desulfonamidative coupling with the amide to form dibenzolactams, which offers a complementary synthetic pathway to unsymmetric dibenzolactams. These protocols exhibit excellent compatibility with reactive functional groups, including halogens, providing an innovative synthetic toolbox for the development of thermally activated delayed fluorescence (TADF) materials used in organic light emitting diodes (OLEDs). DMAC‐PDO, incorporating a dibenzolactam as the acceptor unit, serves as an efficient blue TADF emitter with a maximum external quantum efficiency (EQEmax) of 23.4 %.

De(sulfon)amidative Cyclization: The Synthesis of Dibenzolactams and Dibenzosultams for Organic Light Emitting Diode Materials.

This study addresses a challenge in organic synthetic chemistry: the direct cleavage of amide bonds, which is typically hampered by the thermodynamic stability of the C(Ar)-C(acyl) bond. Previous methods often rely on "CO" extrusion-jointing transition metal-catalyzed process and require activated tertiary amides, limiting their applicability due to incompatibility with reactive functional groups such as halogens. Herein, we report a transition metal-free approach for the deamidative cyclization of biaryl diamides via a radical process, yielding dibenzolactam derivatives. Along this line, we have developed the desulfonamidative cyclization of biaryl disulfonamides to produce dibenzosultams through direct nucleophilic aromatic substitution, demonstrating high selectivity for unsymmetrical structures. Additionally, unsymmetrical sulfamoyl biaryl amides, containing both amide and sulfonamide functionalities, can selectively undergo desulfonamidative coupling with the amide to form dibenzolactams, which offers a complementary synthetic pathway to unsymmetric dibenzolactams. These protocols exhibit excellent compatibility with reactive functional groups, including halogens, providing an innovative synthetic toolbox for the development of thermally activated delayed fluorescence (TADF) materials used in organic light emitting diodes (OLEDs). DMAC-PDO, incorporating a dibenzolactam as the acceptor unit, serves as an efficient blue TADF emitter with a maximum external quantum efficiency (EQEmax) of 23.4 %.

Photoassisted electron emission from planar-type electron source based on graphene/oxide/silicon structure

This paper reports on photoassisted electron emission from a planar-type electron emission source based on a graphene/oxide/p-Si structure under visible laser light irradiation. The electron source is expected to be useful as a photocathode with a high quantum efficiency and an ultrafast pulsed electron beam. The electron emission efficiency is found to be 12%, independent of laser light irradiation. Without a negative electron affinity surface, the emission current generated by irradiation shows an increase of several orders of magnitude compared with that in the dark, and a quantum efficiency of 0.3% is achieved. This electron source exhibits advanced photoassisted electron emission characteristics with high photosensitivity in the order of milliamps per watt. The photoassisted emission from the device shows a photoresponse with a rise and fall time of 70 μs at a wavelength of 633 nm, which is determined by the diffusion process of photoexcited electrons in the bulk. The use of a heavily doped p-type silicon substrate provides a practical route for further improvement.

Coupling coordination and spatial network characteristics of carbon emission efficiency and urban green innovation in the Yellow River Basin, China.

Carbon emission and sustainable development have attracted global attention. Promoting urban green innovation (UGI) in the Yellow River Basin (YRB) will help in lowering the intensity of carbon emissions and improve the safety and sustainability. A SBM-DEA model was constructed to measure carbon emission efficiency (CEE) and the degree of coupling and coordination with UGI was calculated in 73 prefecture-level cities in the YRB. The spatial association network of CEE coupled with UGI is constructed by using a modified gravity model, social network analysis and the quadratic assignment procedure (QAP), to analyze spatial potential energy, network characteristics and clustering characteristics. The study found that: (1) The coupling coordination degree of CEE and UGI in the YRB shows fluctuating growth, mutual promotion and continuous coordinated development. (2) The spatial linkage between CEE and UGI is gradually close, and the potential energy of the spatial linkage increases year by year, with obvious spatial spillover effect, indicating that the radiation and influence between cities are gradually increasing. In contrast to the middle stream, the upstream and downstream regions show a higher percentage of spatial potential energy in the entire network, and their network structure is more intricate and robust. (3) The clustering patterns of the three major urban clusters are examined using the block model, exploring the positioning and functions of various cities in these urban conglomerations, which includes the net spillover, net benefit, two-way spillover and broker plate, so as to strengthen the connection and coordinated development between cities. (4) Factors such as spatial adjacency, industrial structure, population density, digital economy and urbanization level, and energy intensity significantly impact the spatial association network, along with temporal and regional heterogeneity. Therefore, tailored policies are needed in the YRB to strengthen collaboration between CEE and UGI, fostering the development of a circular economy and promoting sustainable development.

Precise Regulation of the Reverse Intersystem Crossing Pathway by Hybridized Long-Short Axis Strategy for High-Performance Multi-Resonance TADF Emitters.

Multi-resonance thermally activated delayed fluorescence (MR-TADF) molecules have experienced great success in organic light-emitting diodes (OLEDs) owing to their outstanding quantum efficiencies and narrow full width at half-maximums (FWHMs). However, the reverse intersystem crossing (RISC) rates of MR-TADF emitters are usually small, which will lead to relatively long triplet exciton lifetime and severe efficiency roll-off. Here, we report an effective molecular design strategy to introduce multichannel RISC pathways and thus increase RISC rates without compromising the color fidelity and emission efficiency by the "hybridized long-short axis (HLSA)" strategy. The TPA-CN-BN shows a near-unity photoluminescence quantum yield, rapid RISC rate of 1.4 × 105 s-1, narrow FWHM of 23 nm, and small singlet-triplet energy gap (ΔEST) of 0.06 eV in solution. The non-sensitized OLED based on TPA-CN-BN exhibits a narrowband emission with the FWHM of 31 nm, in company with external quantum efficiency (EQE) of 37.9%. Notably, the device exhibits the low efficiency roll-off as the EQEs maintain 34.8% and 21.8% at 100 and 1000 cd m-2, respectively, representing the best performance for single-host OLEDs based on the BCzBN skeleton. This study provides a fresh and promising approach to realize high-performance OLEDs with high color purity and remarkable device efficiency.

Precise Regulation of the Reverse Intersystem Crossing Pathway by Hybridized Long‐Short Axis Strategy for High‐Performance Multi‐Resonance TADF Emitters

AbstractMulti‐resonance thermally activated delayed fluorescence (MR‐TADF) molecules have experienced great success in organic light‐emitting diodes (OLEDs) owing to their outstanding quantum efficiencies and narrow full width at half‐maximums (FWHMs). However, the reverse intersystem crossing (RISC) rates of MR‐TADF emitters are usually small, which will lead to relatively long triplet exciton lifetime and severe efficiency roll‐off. Here, we report an effective molecular design strategy to introduce multichannel RISC pathways and thus increase RISC rates without compromising the color fidelity and emission efficiency by the “hybridized long‐short axis (HLSA)” strategy. The TPA‐CN‐BN shows a near‐unity photoluminescence quantum yield, rapid RISC rate of 1.4×105 s−1, narrow FWHM of 23 nm, and small singlet‐triplet energy gap (ΔEST) of 0.06 eV in solution. The non‐sensitized OLED based on TPA‐CN‐BN exhibits a narrowband emission with the FWHM of 31 nm, in company with external quantum efficiency (EQE) of 37.9 %. Notably, the device exhibits the low efficiency roll‐off as the EQEs maintain 34.8 % and 21.8 % at 100 and 1000 cd m−2, respectively, representing the best performance for single‐host OLEDs based on the BCzBN skeleton. This study provides a fresh and promising approach to realize high‐performance OLEDs with high color purity and remarkable device efficiency.

Analysis of spatial and temporal characteristics and evolution of green total factor productivity in agriculture in the lower Yellow River basin

The construction of ecological barriers in the Yellow River Basin represents a significant step toward reducing agricultural carbon emissions, achieving carbon neutrality, and reaching carbon peaking in China. The diverse agrarian development objectives of various regions within the basin have resulted in a heterogeneous approach to greening agriculture. Therefore, this paper will evaluate the development of carbon sink agriculture across 34 cities and municipalities in the lower Yellow River basin from 2008 to 2021 based on the EBM-GML model, and analyze the spatial-temporal evolution of agricultural green total factor productivity (AGTFP) in each region through the application of the Moran index, kernel density estimation, and spatial Markov chain analysis. The results demonstrate that agricultural carbon emissions in the Lower Yellow River Basin gradually decreased throughout the study period. Furthermore, overall carbon emission efficiency improved, indicating significant potential for further emission reduction. In addition, Agricultural Green Technology Progress (AGTC) has become a primary driver of AGTFP growth, while Agricultural Green Technology Efficiency (AGEC) has demonstrated a gradual upward trend. Locally, most areas are weakly connected and display an isolated development trend. The results of the kernel density analysis demonstrate a notable degree of mobility in the distributional dynamics of AGTFP growth, characterized by a gradual narrowing of the gap between locations. The transfer of (AGTFP) types in the lower reaches of the Yellow River Basin is stable, with a noticeable “club convergence” phenomenon, while geographical conditions significantly influence the transfer of AGTFP types in this region. Based on long-term trend predictions, the future trajectory of AGTFP in the lower Yellow River Basin appears optimistic and is expected to improve progressively, with the overall distribution tending toward equilibrium.

Isolated red quantum wells with strain relaxation induced by V-pits and trench structures

Carrier localization leads to efficient emission in InGaN/GaN multi-quantum wells (MQWs), especially in the long-wavelength range. Nanostructures in MQWs can facilitate the formation of carrier localization centers. In this work, high-density V-pits and trench structures were introduced in MQWs by constant low-temperature growth. Isolated red MQWs were achieved due to the carrier blocking effect caused by the V-pits and trench structures. Meanwhile, the V-pits and trench structures caused significant stress relaxation in MQWs. The topmost quantum wells (QWs) achieved red emissions due to the composition-pulling effect, while the bottom QWs exhibited green emissions. In electroluminescence measurement, a single red emission peak appeared at 636 nm at 0.1 A/cm2. Temperature-dependent photoluminescence (PL) results showed that the PL integral intensity of the red MQWs at room temperature is about 11.32% of that at 6 K, while that of the green MQWs is only 0.09%. The PL lifetime for red emissions was more than 20 times longer than that for green ones. This study presents a new method to achieve carrier localization in red MQWs to minimize defect-related effects.

Eu3+@Cs4SnBr6 NCs-doped silicate glass with efficient tunable white light emission via energy transfer and multi-emission photoluminescence properties

Light sources with spectral distributions akin to sunlight are highly desirable. To date, the emulation of solar radiation remains a significant challenge for scientists. In this study, The Cs4SnBr6 NCs were in-situ precipitated from the silicate glass matrix, and the emission spectra were thoroughly investigated. It was found that the coupling of the emission from Cs4SnBr6 NCs with that of Sn2+ resulted in broadband visible light emission. But the emission did not span the entire visible spectrum due to the lack of red emission. Thus, the Eu3+ was introduced into the Cs4SnBr6 NCs-doped silicate glass. By optimizing the concentration of Eu3+ and engineering the energy transfer, broadband emission covering the full visible range with excellent luminescence thermal stability and superior chromatic performance was achieved. A prototype w-LED based Eu3+@Cs4SnBr6 NCs glass exhibits a sunlight-like visible spectrum, with favorable color coordinates (0.31, 0.30), a correlated color temperature (CCT) of 6800 K, and a high color rendering index (CRI) of 91.1. Besides, a unique multi-emission photoluminescence of Eu3+@Cs4SnBr6 NCs glass with color change phenomenon was exhibited by varying the excitation wavelength, offering new avenues for applications in information encryption.