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Effect of temperature on the performance of perovskite solar cells
摘要： The poor stability of perovskite solar cells is a crucial obstacle for its commercial applications. Here, we investigate the thermal stability of the mixed cation organic–inorganic lead halide perovskites (FAPbI3)1?xMAPb(Br3?yCly)x films and devices in air atmosphere. The results show that with the increase of heat treatment from 25 to 250 °C, the MA-perovskite decomposed into PbI2 firstly and the efficiency of corresponding solar cells reduced linearly. For the perovskite film, the increased heat treatment temperature can bring the redshift of the absorption edge leading to the decrease of band gap from 1.569 to 1.508 eV and increase of defect density from 3.87 × 1017 cm?3 to 9.03 × 1017 cm?3. However, a proper heat treatment time (10 min) at certain temperature (85 °C) can passivate defects effectively and improve the efficiency to 16.50%, realizing a 15% relative improvement of average efficiency. This work reveals a detailed thermal decomposition behavior of perovskite material and solar cells, which may provide insights into the stability of perovskite solar cells.
关键词： defect passivation,heat treatment,perovskite solar cells,thermal stability,mixed cation organic–inorganic lead halide perovskites
更新于2025-09-23 15:19:57
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Morphology control and luminescence properties of red-emitting BaSiF6:Eu3+ hexagonal nanorod phosphors for WLEDs
摘要： To promote the development of solid-state lighting industry, exploring excellent inorganic phosphors has been always a scientific and applied hot issue. Herein, a series of efficient red BaSiF6:Eu3+ hexagonal nanorod phosphors with varied size and morphology were successfully prepared through a hydrothermal route. The reaction time, dosage of surfactant and solvent play an important role in the formation of the nanorod structures. The corresponding formation mechanism was discussed and revealed. The effects of surfactant, reaction time and solvent on photoluminescence properties of the as-prepared BaSiF6:Eu3+ nanorod phosphors were investigated in detail. Under excitation at 394 nm, all samples emit bright red light due to the typical Eu3+ 4f-4f transitions. Comparing the luminescence intensity of samples with different size of nanorods, it is found that the length of the nanorod is about 10–20 μm, the luminescence intensity of the sample is 3–5 times of the initial intensity of the nanorod sample that the length is around 30–40 μm. Moreover, when adding ethylene glycol as a solvent, the luminescence intensity of samples with different morphology increases with the increase of the reaction time. Importantly, as the temperature rising to 150 °C, the integrated intensity of the as-prepared sample still could obtain more than 95% of the intensity at room temperature, indicating the phosphors show excellent thermal stability. Thus, the as-prepared BaSiF6:Eu3+ nanorod phosphor is a potential red-emitting phosphor for white light-emitting diodes (WLEDs).
关键词： BaSiF6:Eu3+,luminescence properties,hydrothermal synthesis,thermal stability,WLEDs,hexagonal nanorod phosphors
更新于2025-09-23 15:19:57
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Highly thermally stable all-polymer solar cells enabled by photo-crosslinkable bromine-functionalized polymer donors
摘要： Here, high performance polymers bearing photo-crosslinkable function are developed for all-PSCs to achieve both high efficiency and stability. Then, a series of novel -(D-A)a-(D-D1)b-type photo-crosslinkable bromine (Br)-functionalized polymer donors PBDT(T)FTAZ-BX were synthesized, in which typical benzodithiophene (BDT) derivative was as first component (D), thiophene-difluoro-benzotriazole (FTAZ) derivative was as second component (A), new simple BDT-based functionality appended Br-unit synthesized in this study was as third component (D1). The effects of Br-functionalized component on the photoelectric properties of the polymers were investigated. Moreover, UV-mediated photo-crosslinking effects on performance and thermal stability were thoroughly explored. All-PSCs based on these photo-crosslinkable polymers and N2200, but without photo-crosslinking, displayed a highest PCE of 7.21%, which was achieved by an optimized PBDT(T)FTAZ-B5-based device. As results, photo-crosslinked PBDT(T)FTAZ-B5 + UV5min-based devices afford extraordinarily excellent thermal stability, in which high retention rate of 91.8% of the maximum PCEavg and the intrinsic performance (PCEmax: 6.12%) are maintained even after 72 h 150 °C annealing. For comparison, reference PBDT(T)FTAZ-based devices only display PCEmax value of 5.13% and retain 84.2% of their maximum PCEavg under same aging. This contrasting result indicates that developing photo-crosslinkable Br-functionalized polymers is an effective strategy to further advance in both stability and efficiency of all-PSCs.
关键词： Bromine-functionalized,All-polymer solar cells,Thermal stability,Photo-crosslinkable
更新于2025-09-23 15:19:57
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(Ba,Sr)LaZnTaO6:Mn4+ far red emission phosphors for plant growth LEDs: structure and photoluminescence properties
摘要： It is necessary to develop novel high-efficient red or far-red-emitting in order to facilitate the phosphor-converted light-emitting diodes (pc-LEDs) for plant growth. This work reports a series of novel far-red emitting (Ba,Sr)LaZnTaO6:xMn4+ phosphors with double perovskite structure synthesized by traditional high-temperature solid-state reaction (SSR) process. The crystal structure and morphology of (Ba,Sr)LaZnTaO6 are investigated by high-resolution TEM, SEM, and XRD Rietveld refinement. The photoluminescece properties are systematically explored and analyzed by diffuse reflection (DR) spectra, photoluminescence emission (PL) and excitation (PLE) spectra, decay curves and temperature-dependent spectra. Mn4+ ions occupy Ta5+ sites located at [TaO6] octahedral emitting red light with peak at 698 nm in BaLaZnTaO6:Mn4+ and 695 nm in SrLaZnTaO6:Mn4+ under n-UV and blue light excitation. The critical quenching concentration of Mn4+ was determined to be 0.008. The concentration quenching mechanism could be a dipole-dipole interaction between Mn4+ ions. In addtion, the PL intensity of (Ba,Sr)LaZnTaO6:xMn4+ phosphors decrease with increasing temperature. The SrLaZnTaO6:xMn4+ sample has better thermal stability than BaLaZnTaO6:xMn4+. Interestingly, (Ba,Sr)LaZnTaO6:0.008Mn4+ exhibits outstanding internal quantum efficiency (IQE ≥ 80 %). Fianally, the fabricated of LEDs are combined with SrLaZnTaO6:0.008Mn4+ phosphors combined with 460 nm InGaN chips, which emit blue and red light. Based on above properties, the rare-earth-free (Ba,Sr)LaZnTaO6:xMn4+ phosphors have great potentials to be serviced as far-red emitting phosphors in high-power plant growth LEDS.
关键词： double perovskite structure,phosphor-converted light-emitting diodes,internal quantum efficiency,far-red emitting,plant growth,Mn4+,thermal stability,photoluminescence,solid-state reaction
更新于2025-09-23 15:19:57
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Spectroscopic studies of silica-incorporated lanthanum ?2-diketonate complexes for application in optoelectronic devices
摘要： In the present research work, silica-incorporated complexes of lanthanum β-diketonate were synthesized. Structural characterization of the prepared complexes was made on the basis of FTIR and FESEM studies. Shifting of peaks in the FTIR spectra are discussed in relation with the complexation, also incorporation of silica in complexes was confirmed by the FTIR spectra. FESEM and EDX studies were performed to know the surface morphology as well as elemental composition of the prepared complexes. The optical properties such as diffuse reflectance and photoluminescence were studied to get the idea about the possible transitions among the energy levels of the complexes as well as to know the emission peaks. The assignment of luminescence band is determined from excited state lifetime. The variation in luminescence intensity with time was measured by recording decay curves at fixed emission wavelength. The life time for all the three complexes was measured in micro-second (μs) order. Color coordinates of the complexes lie in the blue region. Thermal stability of the complexes was checked by measuring the loss in weight as a function of temperature.
关键词： FESEM,silica-incorporated lanthanum β-diketonate,FTIR,thermal stability,photoluminescence
更新于2025-09-23 15:19:57
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Enhanced Efficiency and Stability of Nonfullerene Ternary Polymer Solar Cells Based on Spontaneously Assembled Active Layer: The Role of a High Mobility Small Molecular Electron Acceptor
摘要： It is challenging to afford efficient and stable organic solar cells based on the as-cast active layer without any external treatments. We present a planar organic electron acceptor BPTCN with high electron mobility as a third component in nonfullerene ternary polymer solar cells, which comprises an electron-deficient 4,7-bis(5H-4,6-dioxothieno[3,4-c]pyrrol-1-yl)benzo[c][1,2,5]thiadiazole core, doubly endcapped by 2-(3-ethyl-5-methylene-4-oxothiazolidin-2-ylidene)malononitrile through the alkylated thiophene-2,5-ylene unit. It shows a π-π stacking distance of 3.60 ? and μe of 1.31 × 10?3 cm2 V?1 s?1. BPTCN exhibits an absorption maximum at 569 nm in the as-cast film and good miscibility with the NIR-absorption acceptor COi8DFIC, leading to complete f?rster energy transfer in the blends. Adding BPTCN into the PTB7-Th:COi8DFIC blend produces multiple beneficial effects: i) facilitating exciton dissociation and charge transfer at the donor/acceptor interface while suppressing bimolecular and trap-assisted recombination by analysis of the Jph–Veff, Jsc–Ilight and Voc–Ilight characteristics, ii) increasing hole and in particular electron transport; and iii) generally promoting the crystallinity of the polymer donor PTB7-Th, as revealed by grazing incidence X-ray diffraction. Moreover, the phase purity is greatly improved in the ternary blend PTB7-Th:COi8DFIC:BPTCN (1:1.05:0.45 by weight). Consequently, the tentatively optimized ternary solar cell provides a PCE of 11.62% with Voc = 0.74 V, Jsc = 25.93 mA cm-2 and FF = 60.61% in comparison with the binary systems PTB7-Th:COi8DFIC (PCE of 9.41%) and PTB7-Th:BPTCN (6.42%) in the absence of any extra treatments. After thermal aging at 80 oC for 450 h, this ternary solar cell exhibits increased stability with PCE retaining 84.39% of the initial value.
关键词： PTB7-Th,COi8DFIC,BPTCN,electron acceptor,organic solar cells,thermal stability,nonfullerene ternary polymer solar cells
更新于2025-09-23 15:19:57
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Asymmetrically noncovalently fused-ring acceptor for high-efficiency organic solar cells with reduced voltage loss and excellent thermal stability
摘要： Simultaneously broadening the spectral response and reducing the energy loss are challenging tasks in the material design of organic solar cells (OSCs). Herein, a novel asymmetrically noncovalently fused-ring electron acceptor (NFEA) with unilateral alkylthio-substituted thiophene π-bridge, namely IDST-4F, is synthesized. IDST-4F exhibits a broader absorption, higher-lying energy levels, larger dipole moments and suppressed crystallinity than its symmetric counterpart (ID-4F) without the π-bridge. Compared to the devices of PM6:ID-4F, the optimized PM6:IDST-4F-based devices display simultaneously enhanced current density and photovoltage, resulting in an excellent power conversion efficiency (PCE) of 14.3%, which is the highest value among the OSCs based on NFEAs reported in the literature to date. More importantly, the PM6:IDST-4F-based OSCs possess excellent thermal stability with 82% of the initial PCE after thermal treatment at 150 °C for 1200 min. In summary, this study indicates that asymmetrically NFEAs are promising to achieve high efficiency with excellent thermal stability.
关键词： Organic solar cells,Noncovalently fused rings,Thermal stability,Narrow-bandgap acceptor,Energy loss
更新于2025-09-23 15:19:57
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Enhancement of nonlinear optical and thermal properties of polyurethanes by modifying the chromophores with fused heterocyclic and pyrimidine rings
摘要： This article describes the synthesis of substituted triazolo[3,4-b]-thiadiazole heterocycles based nonlinear optical (NLO) responsive chromophores. To enhance the NLO properties of the chromophores, the pyrimidine ring was introduced with an appropriate π-bonding. With these chromophores, different series of polyurethanes were prepared by condensation with tolylene-2,4-diisocyanate and 3,30-dimethoxy-4,40-biphenylene diisocyanate. The structure of the resulting chromophores and polyurethanes was confirmed using Fourier transform infrared, proton nuclear magnetic resonance, and Carbon Hydrogen Nitrogen (CHN) analyzer. The inherent viscosities (ηinh) of the polyurethanes measured by Ubbelohde viscometer were in the range of 0.2324–0.2760 dl/g. Thermal behavior of the polyurethanes was investigated using differential scanning calorimetry and thermogravimetric analysis. The molecular orientation in polyurethane films was induced by a corona poling, and this was ascertained using ultraviolet-visible spectrophotometer and atomic force microscope. The thicknesses and refractive indices of thin films were determined by an Ellipsometer. Polyurethanes exhibited excellent solubility in most of the common organic solvents. The second harmonic generation (SHG) coefficients (d33) of the poled polyurethanes ranged from 63.20 and 95.32 pm/V at 532 nm. None of the polyurethanes showed SHG decay below 100°C, and retained 95% of the signal even up to 500 h. The resulting enhanced NLO efficiency and longer temporal stability make these polyurethanes as promising candidates for photonic devices.
关键词： Polyurethanes,Second harmonic generation,Chromophores,Thermal stability,Nonlinear optical materials
更新于2025-09-23 15:19:57
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The effect of templates on the morphological and optical properties of BaMgAl10O17:Eu2+ phosphors
摘要： Blue light emitting BaMgAl10O17:Eu2+ phosphors were prepared by solution combustion synthesis method using urea as a fuel. Water-soluble templates, β-cyclodextrin and thioglycerol were used for the synthesis process. The main aim of the present work is to study the effect of these templates on morphology and optical properties of BaMgAl10O17:Eu2+ phosphor. The inclusion of templates prevents agglomeration, hence improving crystallinity and photoluminescence emission intensity. β-cyclodextrin and thioglycerol modified the morphology of BaMgAl10O17:Eu2+ phosphor by transforming its multifaceted plate-like to rod-like morphology. It is observed that the addition of β-cyclodextrin and thioglycerol in the synthesis of BaMgAl10O17:Eu2+ phosphor not only increased the photoluminescence emission of BaMgAl10O17:Eu2+ phosphor but also enhanced the thermal stability of the BaMgAl10O17:Eu2+ phosphor. Hence the use of β-cyclodextrin and thioglycerol was beneficial in improving the crystallinity, photoluminescence characteristics and the thermal stability of BaMgAl10O17:Eu2+ phosphor.
关键词： blue emission,photoluminescence,thermal stability,europium,polymer
更新于2025-09-23 15:19:57
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Structure, thermal stability and optical simulation of ZrB2 based spectrally selective solar absorber coatings
摘要： In the present work, a solar selective coating of ZrB2/Al2O3 was deposited onto stainless steel (SS) substrates using a magnetron sputtering system. The coating exhibited an good selective absorbing properties with an absorptance of 0.92 and an emittance of 0.11. To investigate the thermal stability of the coating, the samples were annealed at 500 °C and 600 °C for 100 h, respectively. Experimental results indicated that the coating was thermally stable at 500 °C. The structure and optical properties of the coating is also characterized using ultra-high resolution scanning electron microscope, UV–vis–NIR spectrophotometer, Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS). The re?ectance spectra of the SS/ZrB2/Al2O3 coating was successfully simulated by CODE software.
关键词： Solar absorber coating,Optical simulation,Structure,Thermal stability
更新于2025-09-19 17:15:36