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A new approach for photovoltaic module cooling technique evaluation and comparison using the temperature dependent photovoltaic power ratio
摘要： Many photovoltaic module cooling techniques are available to reduce the solar cell temperature, resulting in enhanced e?ciency. Although the power of the photovoltaic module is usually reported as a measure for the performance of the cooling technique, the performance assessment and comparison among di?erent coolers become di?cult if di?erent photovoltaic module’s reference power is being utilized. The existing method requires calculations to be done repeatedly to obtain the photovoltaic module’s power, for any given value of the reference power. In order to compare the performance of the coolers, the use of the same reference power is needed, resulting in a lengthy process. Hence, a new assessment method is proposed, based on the temperature dependent photovoltaic module’s power ratio that is de?ned and derived. The new method identi?es the relevant parameters that are essential for measuring the performance of the cooler such as the power of a photovoltaic module with a cooler and the reference power at photovoltaic module’s standard test conditions. The outcome is that the calculation of the unknown power for di?erent reference power can be instantly obtained and the performance comparison among di?erent coolers become simple without going through the lengthy process as it is in the case of the existing method. It is shown that the proposed method has the same results as the existing method which is experimentally validated. This is evidence to support the new method which may have potential to be applied by photovoltaic module cooling techniques designers.
关键词： Photovoltaic power ratio,Comparison,Cooling techniques,Photovoltaic module,Evaluation,Photovoltaic e?ciency
更新于2025-09-23 15:19:57
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Efficient near ultraviolet organic light-emitting diode based on PVK material doped with BCPO molecules
摘要： Near ultraviolet organic light-emitting diodes (NUV-OLEDs) have a wide range of applications. However, when large band-gap polymer of PVK was used as the emitting material, its poor electron transportation capability resulted in a large amount of charge accumulation on both sides of light-emitting layer/electron-transporting layer interface of the device, hence generating intense electroplex emission and seriously reducing the e?ciency of NUV light-emitting. In order to solve this issue, BCPO molecules were doped in PVK with certain concentrations, forming PVK:BCPO mixing light-emitting layers. As compared with pure PVK, electron transportation capability was apparently increased in PVK:BCPO mixing layers. On one hand, charge accumulation at the interface was substantially weakened, and the electroplex emission was inhibited. On the other hand, transportations of electron and hole carriers became more balanced in light-emitting layer. Both of these improvements e?ectively promoted device performance. At appropriate BCPO doping concentration, the external quantum e?ciency of PVK:BCPO-based NUV-OLEDs reached the maximum value of ～2.6 %. Further experimental progress would bring it closer to the practical application in future.
关键词： Electroplex,Near ultraviolet,E?ciency,Organic light-emitting diode
更新于2025-09-23 15:19:57
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An Empirical Study on the Efficiency and Influencing Factors of the Photovoltaic Industry in China and an Analysis of Its Influencing Factors
摘要： The photovoltaic (PV) industry in China is still in the early stage of development and is extremely unbalanced; breakthroughs in key technologies are necessary. To achieve high e?ciency and sustainable development, it is important to identify the bottleneck of the whole industry chain through the analysis of overall industrial technical e?ciency. Based on the current situation of the PV industry, this study builds the data envelopment analysis (DEA) model to respectively evaluate the e?ciency of PV devices and power generation in the PV industrial chain. The Tobit model is used to conduct an empirical analysis of the factors a?ecting the e?ciency of the PV industry. The results show that the industrial e?ciency of PV devices is at a medium level and that it is necessary to strengthen regulation and awareness at the industrial scale. However, the PV power generation industry as a whole is at a low e?ciency level, especially the inadequate technical level, which has a negative impact on the improvement of industrial e?ciency. Finally, countermeasures and suggestions at the enterprise and government level are put forward to improve the e?ciency of the PV industry in China.
关键词： technical e?ciency,PV industry,data envelopment analysis,renewable energy
更新于2025-09-23 15:19:57
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Optimization of efficient monolithic perovskite/silicon tandem solar cell
摘要： Solar cells based on multi-junctions are considered to be the most e?cient way of improving the cell’s sunlight to electrical energy conversion e?ciency. In this paper, we simulated monolithic tandem solar cell comprised of high and low bandgap materials i.e., perovskite/silicon layers, separated by a recombination layer made of Spiro-MeOTAD/Silicon, a window layer formed from zinc oxide (ZnO), a bu?er layer formed from cadmium sul?de (CdS), and a heavily doped back surface ?eld layer made of n++Si to stop the recombination at the back surface. The stated structure is investigated numerically and optimized for di?erent parameters, which include bandgap, thickness of active layers, and dopant concentration. The obtained photovoltaic parameters are: open circuit voltage (Voc) =1.779V, short circuit current density (Jsc) =20.19 mA/cm2, ?ll factor (FF) = 82.22 %, and e?ciency (η) = 28.50 %, respectively. Additionally, we tested the optimized solar cell design for high temperatures, and it turned out that temperature had very little e?ect on the cell, showing superior performance than conventional multi-junction structures.
关键词： Perovskite,Temperature,E?ciency,Bandgap
更新于2025-09-23 15:19:57
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Repeatability and Reproducibility of Measures of Bovine Methane Emissions Recorded using a Laser Detector
摘要： Methane (CH4) emissions represent a worldwide problem due to their direct involvement in atmospheric warming and climate change. Ruminants are among the major players in the global scenario of CH4 emissions, and CH4 emissions are a problem for feed e?ciency since enteric CH4 is eructed to the detriment of milk and meat production. The collection of CH4 phenotypes at the population level is still hampered by costly and time-demanding techniques. In the present study, a laser methane detector was used to assess repeatability and reproducibility of CH4 phenotypes, including mean and aggregate of CH4 records, slope of the linear equation modelling the aggregate function, and mean and number of CH4 peak records. Five repeated measurements were performed in a commercial farm on three Simmental heifers, and the same protocol was repeated over a period of three days. Methane emission phenotypes expressed as parts per million per linear meter (ppm × m) were not normally distributed and, thus, they were log-transformed to reach normality. Repeatability and reproducibility were calculated as the relative standard deviation of ?ve measurements within the same day and 15 measurements across three days, respectively. All phenotypes showed higher repeatability and reproducibility for log-transformed data compared with data expressed as ppm × m. The linear equation modelling the aggregate function highlighted a very high coe?cient of determination (≥0.99), which suggests that daily CH4 emissions might be derived using this approach. The number of CH4 peaks resulted as particularly diverse across animals and therefore it is a potential candidate to discriminate between high and low emitting animals. Results of this study suggest that laser methane detector is a promising tool to measure bovine CH4 emissions in ?eld conditions.
关键词： sustainability,e?ciency,environment,methane emission
更新于2025-09-23 15:19:57
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The Quantum Efficiency Roll-Off Effect in Near-Infrared Organic Electroluminescent Devices with Iridium Complexes Emitters
摘要： The electroluminescence quantum e?ciency roll-o? in iridium(III)-based complexes, namely Ir(iqbt)2(dpm) and Ir(iqbt)3 (iqbt = 1 (benzo[b]thiophen-2-yl)-isoquinolinate, dpm = 2,2,6,6-tetramethyl-3,5-heptanedionate) utilized as near-infrared emitters in organic light emitting diodes with remarkable external quantum e?ciencies, up to circa 3%, 1.5% and 1%, are measured and analyzed. With a 5–6 weight% of emitters embedded in a host matrix, the double-layer solution-processed structure as well as analogous three-layer one extended by a hole-conducting ?lm are investigated. The triplet-polaron, the Onsager electron-hole pair dissociation and the triplet-triplet annihilation approaches were used to reproduce the experimental data. The mutual annihilation of triplets in iridium emitters was identi?ed as prevailingly controlling the moderate roll-o?, with the interaction between those of iridium emitters and host matrixes found as being less probable. Following the ?tting procedure, the relevant rate constant was estimated to be (0.5 ? 12) × 10?12 cm3/s, values considered to be rather too high for disordered organic systems, which was assigned to the simplicity of the applied model. A coexistence of some other mechanisms is therefore inferred, ones, however, with a less signi?cant contribution to the overall emission quenching.
关键词： infrared emitters,iridium complex,quantum e?ciency roll-o?,triplet-triplet annihilation,OLEDs
更新于2025-09-23 15:19:57
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Self-Aligned Hierarchical ZnO Nanorod/NiO Nanosheet Arrays for High Photon Extraction Efficiency of GaN-Based Photonic Emitter
摘要： Advancements in nanotechnology have facilitated the increased use of ZnO nanostructures. In particular, hierarchical and core–shell nanostructures, providing a graded refractive index change, have recently been applied to enhance the photon extraction e?ciency of photonic emitters. In this study, we demonstrate self-aligned hierarchical ZnO nanorod (ZNR)/NiO nanosheet arrays on a conventional photonic emitter (C-emitter) with a wavelength of 430 nm. These hierarchical nanostructures were synthesized through a two-step hydrothermal process at low temperature, and their optical output power was approximately 17% higher than that of ZNR arrays on a C-emitter and two times higher than that of a C-emitter. These results are due to the graded index change in refractive index from the GaN layer inside the device toward the outside as well as decreases in the total internal re?ection and Fresnel re?ection of the photonic emitter.
关键词： ZnO nanorod/NiO nanosheet,photon extraction e?ciency,photonic emitter,self-align,hierarchical nanostructures
更新于2025-09-23 15:19:57
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A novel hybrid system consisting of a dye-sensitized solar cell and an absorption refrigerator for power and cooling cogeneration
摘要： To improve the energy conversion e?ciency of a dye-sensitized solar cell (DSSC), a novel hybrid system representatively consisting of a DSSC and an absorption refrigerator (APR) is put forward, in which the APR is used to thermally harness the part of high wavelength sunlight that not converted by the DSSC. The amount of heat from the DSSC is calculated, and mathematical formula for energy conversion e?ciencies and output powers of the DSSC, APR and hybrid system are derived. Numerical calculations show that the maximum output power density and maximum energy conversion e?ciency of hybrid system are enhanced by 9.93% and 9.92% in comparison with that of the single DSSC, respectively. Integration of APR to DSSC is a feasible route to effectively improve the energy conversion e?ciency. Comprehensive sensitivity analyses are conducted to explore how the whole hybrid system performance depends on various working conditions and designing parameters, including porous nano-TiO 2 ?lm thickness, photoelectron absorption coe?cient, internal irreversibility factor, heat transfer coe?cient and various temperatures. The research results can provide some new understandings for further enhancing the DSSC performance.
关键词： Parametric study,Dye-sensitized solar cell,E?ciency,Absorption refrigerator,Hybrid system,Output power density
更新于2025-09-23 15:19:57
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Design of Tandem Organic Light Emitting Diode using efficient charge generation layer
摘要： In this work, highly e?cient Tandem Organic Light Emitting Diode (OLED) based on planar organic charge generation layer (CGL) of C70/Pentacene is proposed. It is found that the proposed CGL generate charges as well as exhibits organic photovoltaic type behavior. In addition a very thin layer of Al/LiF and PEDOT:PSS is used as electron and hole injection layer respectively to further increase the transport of electrons and holes from CGL to emissive unit. The current e?ciency and luminance of red tandem device is found to be 29 cd/A and 29010 cd/m2 at 20 mA/cm2 and 100 mA/cm2 respectively which is 1.855 times 1.856 times greater than that of single emitter device having current e?ciency and luminance of 15.63 cd/A and 15630 cd/cm2 at the same current densities Generally, the turn on voltage of Tandem devices is almost double as compared to single unit device. But with the proposed CGL the turn on voltage of red tandem device is found to be 5.9 V which is less than double the turn on voltage of single unit device (3 V). Therefore, the e?ective charge generation and transport property of proposed CGL as well as remarkable high injection property of thin Al layer and PEDOT:PSS leads to the enhancement in the e?ciency of tandem OLED.
关键词： Tandem OLED,Charge generation layer,Electron injection,E?ciency improvement
更新于2025-09-23 15:19:57
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Thermal and electrical performance of a novel photovoltaic-thermal road
摘要： The solar road is a new type of technology for solar energy conversion. As the solar energy utilization e?ciency of a solar road is too low, to solve this issue, a novel photovoltaic-thermal road is proposed in this paper. In addition, a mathematical model is developed to evaluate thermal and electrical performance of the photovoltaic-thermal road, and it is validated by experimental data. Moreover, the performance of a simple water system of the photovoltaic-thermal road is investigated and compared with that of a photovoltaic road. The results show that overall energy e?ciency of the photovoltaic-thermal road system is 3.95 times that of the photovoltaic road system. In addition, this study analyzed the e?ects of some meteorological and geometric parameters on the system performance. The pipe diameter was found to have little e?ect on the overall performance of photovoltaic-thermal road. Furthermore, the solar-radiation intensity, packing factor of photovoltaic cell, mass ?ow rate of circulating water, and transparent surface transmissivity have positive in?uences on the overall energy e?ciency; in contrast, the wind speed and burial depth of the pipe have negative in?uences, implying that a windless environment is conducive to the energy output of the PVTR system. An optimum thermal conductivity of asphalt concrete can maximize the overall energy e?ciency; for this study, the recommended range of this value is from 1.0 to 1.5 W/(m·K). The results of this study substantially contribute to the state of knowledge regarding photovoltaic-thermal road designs.
关键词： Thermal storage e?ciency,Electrical e?ciency,Solar energy,Photovoltaic-thermal road
更新于2025-09-19 17:13:59