Conversion Efficiency and Figure-of-Merit

1995 ◽  
Author(s):  
H Goldsmid
Keyword(s):  
Conversion Efficiency ◽  
Figure Of Merit

scholarly journals Relationship between thermoelectric figure of merit and energy conversion efficiency

2015 ◽  
Vol 112 (27) ◽  
pp. 8205-8210 ◽  
Author(s):  
Hee Seok Kim ◽  
Weishu Liu ◽  
Gang Chen ◽  
Ching-Wu Chu ◽  
Zhifeng Ren
Keyword(s):  
Conversion Efficiency ◽  
Temperature Difference ◽  
Figure Of Merit ◽  
Energy Conversion Efficiency ◽  
Maximum Efficiency ◽  
Thermoelectric Device ◽  
Large Temperature ◽  
Thermoelectric Figure ◽  
Dimensionless Figure Of Merit ◽  
Temperature Dependences

The formula for maximum efficiency (ηmax) of heat conversion into electricity by a thermoelectric device in terms of the dimensionless figure of merit (ZT) has been widely used to assess the desirability of thermoelectric materials for devices. Unfortunately, the ηmax values vary greatly depending on how the average ZT values are used, raising questions about the applicability of ZT in the case of a large temperature difference between the hot and cold sides due to the neglect of the temperature dependences of the material properties that affect ZT. To avoid the complex numerical simulation that gives accurate efficiency, we have defined an engineering dimensionless figure of merit (ZT)eng and an engineering power factor (PF)eng as functions of the temperature difference between the cold and hot sides to predict reliably and accurately the practical conversion efficiency and output power, respectively, overcoming the reporting of unrealistic efficiency using average ZT values.

scholarly journals A Holistic Study on the Effect of Annealing Temperature and Time on CH3NH3PbI3-Based Perovskite Solar Cell Characteristics

2021 ◽  
Vol 9 ◽  
Author(s):  
Mohammad Ali Akhavan Kazemi ◽  
Arash Jamali ◽  
Frédéric Sauvage
Keyword(s):  
Power Conversion Efficiency ◽  
Conversion Efficiency ◽  
Figure Of Merit ◽  
Fill Factor ◽  
Crystallization Process ◽  
Annealing Temperature ◽  
Power Conversion ◽  
Perovskite Solar Cells ◽  
Out Of Plane ◽  
Current Value

The time and annealing temperature for the film crystallization in perovskite solar cells (PSCs) is critical and is at the stake of device optimization. It governs the crystallization process, the film’s morphorlogy and texture and the level of non-radiative defects, which in whole control the power conversion efficiency (PCE). However, deciphering each of these parameters in the device cell characteristics remains not totally clear. In this work, we led a holistic study considering temperature and time for the MAPbI3 crystallization as a free parameter to study how the latter is impacting on the film’s characteristics and how the device figure of merit is affected. The results suggest that the crystallinity level of the grains plays an important role in the photo-current value whereas the morphology and PbI2 impurities resulting from the onset of thermal decomposition of MAPbI3 penalizes the cell photovoltage and the fill factor values. Based on this study, it is highlighted that flash high temperature annealing is beneficial to limit out-of-plane substrate grain boundaries, resulting in a device exhibiting 18.8% power conversion efficiency compared to 18.0% when more standard post-annealing procedure is employed.

Study on Nonlinear Optical Properties of BSS Material

2013 ◽  
Vol 747 ◽  
pp. 497-500
Author(s):  
Wen Dan Cheng ◽  
Chen Sheng Lin ◽  
Zhong Zhen Luo ◽  
Yi Yang
Keyword(s):  
Density Functional Theory ◽  
Optical Properties ◽  
Energy Range ◽  
Conversion Efficiency ◽  
Figure Of Merit ◽  
Density Functional ◽  
Nonlinear Optical ◽  
Nonlinear Optical Properties ◽  
Functional Theory ◽  
The Density Functional Theory

The calculated results based on the density functional theory are employed to simulate the nonlinear optical properties of a new compound of Ba7Sn5S15 (BSS). The frequency (ω=eV/ħ) dependent SHG tensor components of the BSS are calculated from 0.0 to 2.0 eV energy range. The calculated components d31(20.3 pm/V) and d33(18.8 pm/V) are close to the experimental value of of 19.5 pm/V at a wavelength of 2.10 μm. The SHG conversion efficiency and the figure of merit of BSS material are about two fold as compared with those of AgGaS2 material. The charge transfers within the (Sn2S3) and (SnS4) polyhedrons lead to the most contribution to SHG response, and the polarity superposition of the [Sn2S3]2- groups will strengthen the crystal polarity and result in a large SHG response in a BSS material.

scholarly journals Enhanced thermoelectric properties in Sb/Ge core/shell nanowires through vacancy modulation

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Prabal Dev Bhuyan ◽  
P. N. Gajjar ◽  
Rita Magri ◽  
Sanjeev K. Gupta
Keyword(s):  
Electronic Structure ◽  
Thermoelectric Properties ◽  
Conversion Efficiency ◽  
Figure Of Merit ◽  
Formation Energy ◽  
Energy Conversion Efficiency ◽  
Core Shell ◽  
Thermoelectric Energy ◽  
The Stability ◽  
Shell Nanowires

AbstractIn the present work, we have modified the physical and electronic structure of Sb/Ge core/shell nanowires via vacancy creation and doping with foreign atoms with the aim to improve their thermoelectric energy conversion efficiency. Sb/Ge-NWs having a diameter of 1.5 Å show metallicity with 2Go quantum conductance. The stability of the nanowires is assessed through the calculation of their formation energy. The formation of one vacancy at either the Sb- and Ge-site modifies substantially the electronic properties. From the comparison of the thermoelectric properties of the nanowires with and without the vacancy, we have found that the figure of merit for the Sb/Ge NW with one Sb vacancy increases of 0.18 compared to the pristine NW. The NW doping with different transition metals: Fe, Co, Ni and Cu have been found to also enhance the conversion efficiency. Thus, our calculations show that the thermoelectric performance of metal–semiconductor core–shell NWs can be in principle improved as much as 80% by vacancy formation and doping.

Seti Figure of Merit

1997 ◽  
Vol 161 ◽  
pp. 711-717 ◽  
Author(s):  
John W. Dreher ◽  
D. Kent Cullers
Keyword(s):  
Figure Of Merit ◽  
Qualitative Difference ◽  
Current Generation ◽  
Detection Range ◽  
Sky Surveys ◽  
Independent Observations ◽  
Good For

AbstractWe develop a figure of merit for SETI observations which is anexplicitfunction of the EIRP of the transmitters, which allows us to treat sky surveys and targeted searches on the same footing. For each EIRP, we calculate the product of terms measuring the number of stars within detection range, the range of frequencies searched, and the number of independent observations for each star. For a given set of SETI observations, the result is a graph of merit versus transmitter EIRP. We apply this technique to several completed and ongoing SETI programs. The results provide a quantitative confirmation of the expected qualitative difference between sky surveys and targeted searches: the Project Phoenix targeted search is good for finding transmitters in the 109to 1014W range, while the sky surveys do their best at higher powers. Current generation optical SETI is not yet competitive with microwave SETI.

A thiourea additive-based quadruple cation lead halide perovskite with an ultra-large grain size for efficient perovskite solar cells

Nanoscale ◽  
2019 ◽  
Vol 11 (45) ◽  
pp. 21824-21833 ◽  
Author(s):  
Jyoti V. Patil ◽  
Sawanta S. Mali ◽  
Chang Kook Hong
Keyword(s):  
Thin Films ◽  
Grain Size ◽  
Solar Cells ◽  
Power Conversion Efficiency ◽  
Conversion Efficiency ◽  
Power Conversion ◽  
Perovskite Solar Cells ◽  
Inorganic Perovskite ◽  
Halide Perovskite ◽  
Lead Halide

Controlling the grain size of the organic–inorganic perovskite thin films using thiourea additives now crossing 2 μm size with >20% power conversion efficiency.

The Measurement of Performance in Probabilistic Diagnosis IV. Utility Considerations in Therapeutics and Prognostics

1981 ◽  
Vol 20 (02) ◽  
pp. 80-96 ◽  
Author(s):  
J. D. F. Habbema ◽  
J. Hilden
Keyword(s):  
Decision Theory ◽  
Figure Of Merit ◽  
Acute Abdominal Pain ◽  
Theory Approach ◽  
Expected Loss ◽  
Patient Benefit ◽  
Evaluation Approach ◽  
Average Loss ◽  
Actual Decision ◽  
Probabilistic Diagnosis

It is argued that it is preferable to evaluate probabilistic diagnosis systems in terms of utility (patient benefit) or loss (negative benefit). We have adopted the provisional strategy of scoring performance as if the system were the actual decision-maker (not just an aid to him) and argue that a rational figure of merit is given by the average loss which patients would incur by having the system decide on treatment, the treatment being selected according to the minimum expected loss principle of decision theory.A similar approach is taken to the problem of evaluating probabilistic prognoses, but the fundamental differences between treatment selection skill and prognostic skill and their implications for the assessment of such skills are stressed. The necessary elements of decision theory are explained by means of simple examples mainly taken from the acute abdomen, and the proposed evaluation tools are applied to Acute Abdominal Pain data analysed in our previous papers by other (not decision-theoretic) means. The main difficulty of the decision theory approach, viz. that of obtaining good medical utility values upon which the analysis can be based, receives due attention, and the evaluation approach is extended to cover more realistic situations in which utility or loss values vary from patient to patient.

Proteins and direct methods

1991 ◽  
Vol 197 (3-4) ◽  
Author(s):  
Fan Hai-fu ◽  
Hao Quan ◽  
M. M. Woolfson
Keyword(s):  
First Principles ◽  
Figure Of Merit ◽  
Direct Methods ◽  
Large Structure ◽  
Low Resolution ◽  
Figures Of Merit ◽  
Large Structures ◽  
Resolution Data

AbstractConventional direct methods, which work so well for small structures, are less successful for macromolecules. Where it has been demonstrated that a solution might be found using direct methods it is then found that the usual figures of merit are unable to distinguish the few good sets of phases from the large number of sets generated. The reasons for the difficulties with very large structures are considered from a first-principles approach taking into account both the factors of having a large number of atoms and low resolution data. A proposal is made for trying to recognize good phase sets by taking a large structure as a sum of a number of smaller structures for each of which a conventional figure of merit can be applied.

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