In this paper, a temperature indicating device with double-layer planar texture cholesteric liquid crystal (PTCLC) is designed, which has great advantages over temperature card. It works based on the temperature dependence of the cholesteric liquid crystal helical pitch and the Bragg Reflection of PTCLC. A white light source is placed on one side of the waveguide element of the temperature indicating device, and only light of a particular wavelength can form guided wave due to the Bragg Reflection. The feasibility of the temperature indicating device was verified by measuring the Bragg reflectance spectrum and chromaticity coordinates at different temperatures.
Abstract Natural gas distributed energy is recognized as a pivotal means to enhance energy efficiency and mitigate carbon dioxide emissions through localized energy cascading. Positioned as a key option for advancing the Sustainable Development Goals, this system optimizes energy utilization near end-users. While maximizing energy efficiency, it is imperative to address potential environmental challenges. A thorough, comprehensive environmental assessment, facilitated by the life cycle assessment method, proves instrumental in meeting this standard. Employing this method enables an intuitive grasp of the environmental strengths and weaknesses inherent in natural gas distributed energy within the power structure. This insight serves as a foundation for informed project decision-making, fostering the growth of the industry. We selected six environmental impact assessment categories based on the CML 2001 method, and conducted the life cycle analysis across four stages. China's inaugural natural gas distributed energy demonstration project was chosen as a model case, and an environmental impact assessment inventory was established, utilizing survey data and literature for comprehensive data collection and analysis. Results from case testing yield environmental impact assessment outcomes, with a specific sensitivity analysis for stages with notable environmental impact factors. The study underscores that the operation phase has the highest environmental impact, comprising 78.37% of the total combined environmental impact, followed by the fuel production phase. Comparative analyses with coal-fired and conventional natural gas power generation, based on dimensionless literature data, reveal that abiotic resources depletion potential is the primary contributor to the environmental impact of 1 kWh of electricity product, constituting 52.76% of the total impact value, followed by global warming potential. Concrete strategies have been outlined for decision-making in both the operational and planning phases of natural gas distributed energy projects. The strengthening of policies is pinpointed towards grid connection and scale expansion.
It remains a central challenge to the information display community to develop red light-emitting diodes (LEDs) that meet demanding color coordinate requirements for wide color gamut displays. Here, we report high-efficiency, lead-free (PEA)2SnI4 perovskite LEDs (PeLEDs) with color coordinates (0.708, 0.292) that fulfill the Rec. 2100 specification for red emitters. Using valeric acid (VA)-which we show to be strongly coordinated to Sn2+-we slow the crystallization rate of the perovskite, improving the film morphology. The incorporation of VA also protects tin from undesired oxidation during the film-forming process. The improved films and the reduced Sn4+ content enable PeLEDs with an external quantum efficiency of 5% and an operating half-life exceeding 15 hours at an initial brightness of 20 cd/m2 This work illustrates the potential of Cd- and Pb-free PeLEDs for display technology.
Abstract Tandem solar cells involving metal-halide perovskite subcells offer routes to power conversion efficiencies (PCEs) that exceed the single-junction limit; however, reported PCE values for tandems have so far lain below their potential due to inefficient photon harvesting. Here we increase the optical path length in perovskite films by preserving smooth morphology while increasing thickness using a method we term boosted solvent extraction. Carrier collection in these films – as made – is limited by an insufficient electron diffusion length; however, we further find that adding a Lewis base reduces the trap density and enhances the electron-diffusion length to 2.3 µm, enabling a 19% PCE for 1.63 eV semi-transparent perovskite cells having an average near-infrared transmittance of 85%. The perovskite top cell combined with solution-processed colloidal quantum dot:organic hybrid bottom cell leads to a PCE of 24%; while coupling the perovskite cell with a silicon bottom cell yields a PCE of 28.2%.
Blue perovskite light-emitting diodes (LEDs) have shown external quantum efficiencies (EQEs) of more than 10%; however, devices that emit in the true blue—those that accord with the emission wavelength required for Rec. 2100 primary blue —have so far been limited to EQEs of ~6%. We focused here on true blue emitting CsPbBr 3 colloidal nanocrystals (c-NCs), finding in early studies that they suffer from a high charge injection barrier, a problem exacerbated in films containing multiple layers of nanocrystals. We introduce a self-assembled monolayer (SAM) active layer that improves charge injection. We identified a bifunctional capping ligand that simultaneously enables the self-assembly of CsPbBr 3 c-NCs while passivating surface traps. We report, as a result, SAM-based LEDs exhibit a champion EQE of ~12% [CIE of (0.132, 0.069) at 4.0 V with a luminance of 11 cd/m 2 ], and 10-fold–enhanced operating stability relative to the best previously reported Rec. 2100-blue perovskite LEDs.
Abstract Metal halide perovskites have emerged as promising candidates for solution-processed blue light-emitting diodes (LEDs). However, halide phase segregation – and the resultant spectral shift – at LED operating voltages hinders their application. Here we report true-blue LEDs employing quasi-two-dimensional cesium lead bromide with a narrow size distribution of quantum wells, achieved through the incorporation of a chelating additive. Ultrafast transient absorption spectroscopy measurements reveal that the chelating agent helps to control the quantum well thickness distribution. Density functional theory calculations show that the chelating molecule destabilizes the lead species on the quantum well surface and that this in turn suppresses the growth of thicker quantum wells. Treatment with γ-aminobutyric acid passivates electronic traps and enables films to withstand 100 °C for 24 h without changes to their emission spectrum. LEDs incorporating γ-aminobutyric acid-treated perovskites exhibit blue emission with Commission Internationale de l'Éclairage coordinates of (0.12, 0.14) at an external quantum efficiency of 6.3%.
Solid electrolytes are generated through in situ polymerization within batteries, which is one of the most promising methods for achieving solid-state lithium metal batteries with good interfacial contact, high safety, and high performance. Poly-1,3-dioxolane (PDOL), although a good in situ solidified electrolyte for lithium stability, has poor applicability in high-voltage battery systems. In order to improve the interfacial compatibility between PDOL and both the cathode and anode of high-voltage batteries. we herein design a sacrificial additive, diethyl (2,2,2-trifluoroethyl) phosphite (DETFPi), with a lower lowest unoccupied molecular orbital (LUMO) and higher highest occupied molecular orbital (HOMO) energy, through methods of calculation. After being loaded into the battery, DETFPi-DOL is in situ polymerized to form DETFPi-PDOL electrolyte. The Li||DETFPi-PDOL||Li symmetric battery operates stably for 2000 h at 0.5 mA cm–2, with an overpotential of only 16 mV. XPS analysis shows that an SEI layer with high LiF content is formed on the surface of the lithium anode after cycling, which promotes the uniform deposition of lithium ions and inhibits the growth of lithium dendrites. After 300 cycles, the NCM811||DETFPi-PDOL||Li battery exhibits a remaining capacity of 154.8 mAh g–1 (81%) within the 3.0–4.35 V range, meanwhile demonstrating excellent rate performance. Moreover, a uniform CEI layer containing pentavalent phosphorus and low LiF content is formed on the surface of the cathode after battery cycling. Finally, due to the improvement of the cathode interface, the increase of interfacial impedance of the battery after 300 cycles is reduced to half that of the PDOL battery.
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