Total Power Conversion Efficiency Research Articles

Micronuclear battery based on a coalescent energy transducer.

Micronuclear batteries harness energy from the radioactive decay of radioisotopes to generate electricity on a small scale, typically in the nanowatt or microwatt range1,2. Contrary to chemical batteries, the longevity of a micronuclear battery is tied to the half-life of the used radioisotope, enabling operational lifetimes that can span several decades3. Furthermore, the radioactive decay remains unaffected by environmental factors such as temperature, pressure and magnetic fields, making the micronuclear battery an enduring and reliable power source in scenarios in which conventional batteries prove impractical or challenging to replace4. Common radioisotopes of americium (241Am and 243Am) are α-decay emitters with half-lives longer than hundreds of years. Severe self-adsorption in traditional architectures of micronuclear batteries impedes high-efficiency α-decay energy conversion, making the development of α-radioisotope micronuclear batteries challenging5,6. Here we propose a micronuclear battery architecture that includes a coalescent energy transducer by incorporating 243Am into a luminescent lanthanide coordination polymer. This couples radioisotopes with energy transducers at the molecular level, resulting in an 8,000-fold enhancement in energy conversion efficiency from α decay energy to sustained autoluminescence compared with that of conventional architectures. When implemented in conjunction with a photovoltaic cell that translates autoluminescence into electricity, a new type of radiophotovoltaic micronuclear battery with a total power conversion efficiency of 0.889% and a power per activity of 139 microwatts per curie (μW Ci-1) is obtained.

Opto-electrical study of 4T perovskite-chalcogenide tandem solar cell with the addition of quasi-2D perovskite as capping layer of 3D perovskite layer

This study presents a four-terminal (4T) perovskite-chalcogenide tandem solar cell (TSC) that includes quasi-2D perovskite material in the top sub-cell in order to provide a stable structure, and the bottom sub-cell contains Zn(O,S,OH) material to provide a nontoxic buffer layer. First, a reference TSC with a total power conversion efficiency (PCE) of 26.48% is modeled, using MAPbI3 and CIGSSe as 3D perovskite and chalcogenide absorber layers (ALs), respectively. Next, two structures are designed to produce a stable SC using the Ruddlesden Popper (RP) quasi-2D perovskite materials, which have the chemical formula BA2MAm−1PbmI3m+1, m = 2–5. The initial structure uses quasi-2D perovskites in place of the 3D perovskite AL. According to the results, BA2MAPb2I7 represents the maximum PCE of 16.00%, 10.48% less than previously. This is caused by quasi-2D materials’ high Eg and low carrier mobility. In the second structure, 3D perovskite AL is capped with the quasi-2D perovskites. In terms of attaining maximum PCE, the optimal TSC is found for BA2MA3Pb4I13 with a PCE of 25.80%. Compared to the initial structure, this one’s PCE increased by 61.25%. In order to boost PCE, a 80 nm-thick anti-reflection (AR) layer is added to the second structure, and the PCE increased to 27.48%. Therefore, the final TSC is proposed as a 4T quasi-2D/3D perovskite-chalcogenide TSC that is stable, and has nontoxic buffer layer, with 3.78% more PCE than the reference structure.

Luminescence coupling in 28.4%-efficient tandem solar cell utilizing 20.8%-efficient perovskite minimodule stacked on silicon cell

The total power conversion efficiency (PCE) of 28.4% with an aperture area of 64 cm2 on a four-terminal (4T) tandem solar cell with a 20.8% efficiency-semitransparent perovskite module (SPM) with a series interconnection structure and a conventional passivated emitter and rear cell type crystalline silicon solar cell is independently confirmed. This is the independently confirmed record PCE of a 4T perovskite and crystalline silicon tandem solar cell with a structure having the same active area for both top and bottom cells. The impact of the luminescence coupling monitored by the silicon solar cell in the 4T tandem solar cell was investigated based on electrical properties of the top SPM analyzed by a simple one-diode equivalent circuit model.

Optimization of Efficient Perovskite-Si Hybrid Tandem Solar Cells

Perovskite-silicon tandem solar cells have attracted much attention to photovoltaic community because of their high efficiency via easy fabrication methods and availability of precursor material abundant in nature. The properties of both perovskite and silicon meet ideal solar cell standards such as high light absorption potential, long carrier diffusion length and fast charge separation process. Semi-transparent solar cell with widely tunable band gap of perovskite material is compatible with silicon solar cell for tandem structures. A perovskite-silicon tandem solar cell four terminal configuration optimization was performed through numerical simulation. The optimized four terminal perovskite-silicon tandem solar cell performances was investigated by varying the thickness of top and bottom solar cell absorber layers, defect density of the absorber layer, and temperature. Perovskite-silicon tandem solar cell showed better photovoltaic performance under constant illumination condition. A high performance mechanically attached four terminal (4-T) perovskite-silicon tandem solar cell has total power conversion efficiency (PCE) of 34.88% by optimized parameters through simulation. It has shown 37% efficiency with matched current of 23.71mA/cm2. These numerical simulation results are provided the parameter values for further experimental assignment.

Two quasi-interfacial p-n junctions observed by a dual-irradiation system in perovskite solar cells

In general, perovskite solar cells (PSC) with a sensitized or thin-film architecture absorb light from a single-side illumination, and carrier separation and transport only take place inside the active layer of the perovskite film. Herein, we demonstrated a dual-irradiation PSC system in which light passes through both the fluorinated tin oxide (FTO) side and the Au electrode side, resulting in much faster interfacial charge carrier extraction and transportation than that in a single-irradiation system, in which light passes through from either the FTO or semitransparent Au electrode side. This dual-irradiation PSC system with a configuration of FTO/Cl-TiO2/Mp-TiO2/mixed perovskite/spiro-OMeTAD/Au/ITO can form two quasi-interfacial p-n junctions, which occur separately at the interfaces of TiO2/perovskite and perovskite/spiro-OMeTAD. When the PSC device was illuminated simultaneously from both the FTO and Au/ITO sides, the PSC achieved a total power conversion efficiency (PCE) as high as 20.1% under high light intensity (1.4 sun), which is higher than PCE (18.4%) of a single-irradiation system. The time of flight (TOF) photoconductivity, small perturbation transient photovoltaic (TPV), finite-difference time-domain (FDTD) optical simulations, and dual illumination-side-dependent impedance spectroscopy (ISD-IS) were used to authenticate the presence of two quasi-interfacial p-n junctions in the PSC, creating more charge carriers than only one quasi p-n junction, and thus leading to a fast recombination process.

New D−A propeller system with pyridine core for co-sensitization in dye sensitized solar cells

In this study, a propeller-type molecule with a pyridine core (D) was designed and synthesized. Photophysical and electrochemical studies, along with theoretical DFT simulations, indicated that the molecule has suitable light absorption properties and frontier molecular orbital levels for usage as a sensitizer in dye-sensitized solar cells (DSSCs). Meanwhile, the standard dye Z-907 was chosen to investigate the effect of the synthesized molecule as a co-adsorbent dye on DSSCs. Intriguingly, when compared to the D and Z907-based devices, the performance of the co-sensitized Z907 + D cell exhibited an increase in photocurrent (JSC), photo-voltage (VOC), and, as a result, total power conversion efficiency (PCE).

Maximizing tidal energy conversion by adopting hydraulic transformation and LMI based robust control

This paper explores the maximization of tidal energy conversion by adopting hydraulic transformation and through the design of a robust H∞ control scheme. A hydraulic transformation based tidal turbine applicable to realistic tidal states is presented. In this turbine, a hydraulic transformer is developed to have well-adapted characteristics to turbulent tidal stream flows. The dynamics of the tidal turbine is represented as a state space model based on the equations of its main components. The H∞ control scheme is then synthesized by introducing a new state variable that represents the “filtered” of the turbine rotor speed tracking errors. The control problem is formulated as a convex optimization problem with linear matrix inequality (LMI) that is solved to satisfy H∞ performance and obtain good dynamic characteristics. In addition, a robust H∞ observer for estimating state variables along with the online implementations of the robust controller is also designed by using the LMI approach. A case study of a 150 kW hydraulic transformation based tidal turbine system is conducted and detailed analyses of the dynamic behavior of the tidal turbine are presented. According to the test results, approximately up to 40% total power conversion efficiency can be achieved by the proposed turbine under the typical energetic sea state conditions.

Designing and Modeling of a Dual-Band Rectenna With Compact Dielectric Resonator Antenna

In this letter, a compact dual-band rectenna is modeled and developed for low radio frequency (RF) power harvesting. The proposed theoretical model can provide a comprehensive analysis of the rectenna, including the power conversion efficiency (PCE) of the diode, matching efficiency of the rectifier, and total PCE of the rectenna. In the rectenna design, a very compact omnidirectional dielectric resonator antenna (DRA) is proposed with a broad bandwidth exceeding 40%. Meanwhile, a dual-band rectifier is designed based on a single branch in the low-power range with bandwidths covering the two fifth-generation (5G) frequency bands in China (2.515–2.675 and 3.4–3.6 GHz). It was found that the theoretical model can show a high accuracy with the calculation error within 5% in analyzing the dual-band rectifier. The DRA and the dual-band rectifier are integrated to form a compact dual-band rectenna. It shows a higher PCE than those of the existing multiband designs working at similar low-power levels. It is hoped to be implemented in 5G-enabled Internet of Things (IoT) applications for powering wireless sensor nodes.

Investigation of optical and electrical properties of novel 4T all perovskite tandem solar cell

In this paper, a combined three-dimensional (3D) optical-electrical simulation of non-pb and flexible four-terminal (4T) all perovskite tandem solar cell (APTSC) is presented. In this structure, polyethylene terephthalate (PET) is used as substrates, while the top sub cell has a MAGeI_{3} absorber layer and the bottom sub cell has a MASnI_{3} absorber layer. This structure is used as a reference in this paper and the optical and electrical properties of it are investigated using the finite element method (FEM). It is shown that this structure has a total power conversion efficiency (PCE) of 24.65%. Then, the elimination of the buffer layer and the addition of antireflection layer (ARL) strategies, as well as the use of periodic nano-texture patterns, are used to increase the reference structure’s total PCE. A free-buffer layer tandem device is presented to minimize the parasitic absorption. While the total PCE is improved by 1.14% in this case, one of the fabrication steps is also eliminated. A plasma-polymer-fluorocarbon (PPFC) coating layer is suggested as ARL on the substrates of both sub cells to reduce reflection loss. With optimized these layers thickness, total PCE is increased by 12.76%. Because the PPFC layer is hydrophobic, the top surface of two sub cells in this structure has self-cleaning characteristic. As a result, this device offers long-term moisture resistance. Finally, the best structure in terms of the maximum total PCE is presented by increasing optical path-length utilizing nano-photonic and nano-plasmonic structures. The final structure is offered as a 4T tandem solar cell (TSC) that is environmentally friendly, extremely flexible, and has self-cleaning capability, with a total PCE of 30.14%, which is greater than the total PCE of the reference structure by 22.27%.

Accurately Modeling Zero-Bias Diode-Based RF Power Harvesters With Wide Adaptability to Frequency and Power

This paper proposes an analytical method for effectively evaluating the performances of zero-bias diode-based RF power harvesters. The method allows the accurate calculation of both the diode power conversion efficiency (PCE) and matching efficiency, while showing the wide adaptability to frequency and input power. To calculate the diode PCE accurately, the junction voltage is built based on modeling the diode junction capacitance and turn-on voltage. Using the accurate diode PCE, the equivalent nonlinear resistance of the diode is calculated, and thus the diode impedance is obtained. This helps to design a matching network with required bandwidths and evaluate the corresponding matching efficiency. The total PCE of the RF power harvester is finally obtained by multiplying the diode PCE and matching efficiency. For verification, dual-band RF power harvesters based on diodes of SMS7630 and HSMS-2850 are developed to cover the two 5G frequency bands for three telecom operators in China (2.515-2.675, 3.4-3.5 & 3.5-3.6 GHz). They are designed to operate in the low power range of −25-−5 dBm for low power harvesting scenarios. Compared with the simulated results, the calculation discrepancy of less than 3.12% can be achieved in evaluating the total PCEs of the RF power harvesters. Prototypes of the designed RF power harvesters were fabricated and measured for validation. It shows that the proposed analytical method can provide design guidelines for developing a multi-band RF power harvester.

Power generation of thermoelectric generator with plate fins for recovering low-temperature waste heat

Low-temperature waste heat has great potential for renewable power because it accounts for around 60% of total industrial waste heat. This study develops a model of integrating thermoelectric generation, computational fluid dynamics, and plate fins to figure out a low-temperature waste heat recovery system for power generation. The effect of the number of partitions of a thermoelectric module on its performance is examined, and the results show that a single module without a partition can provide accurate predictions. Four different combinations between wastewater and air in the hot and cold channels under three different Reynolds numbers (i.e., Re = 10, 100, and 1,000) on thermoelectric modules’ performance suggest that only combining hot wastewater and cooling water can contribute electricity to a certain extent. By installing fins with a number range of 0–27, it indicates that fin installation can dramatically intensify heat transfer and thermoelectric modules’ performance. The optimal number of fins at Re = 10 and 100 is 21, whereas it is 27 at Re = 1,000. The maximum total output power and mean conversion efficiency are 0.411 W and 0.95%, respectively, with 27 fins at Re = 1,000. These values account for 105.5% and 43.94% improvements when compared to the TEMs without fins. Even though installing fins increases the pressure drop in the channel, its value is much smaller than the generated power (less than1%). The developed method in this study can be used to efficiently and accurately predict the performance of thermoelectric modules, and obtained results have provided practical insights into the design of low-temperature waste heat recovery systems for green power generation.

Determination of power conversion efficiency of CdTe QDs luminescent solar concentrators by analytic model and COMSOL photogeneration model

Luminescent nanomaterials such as cadmium telluride (CdTe) quantum dots (QDs) represent an attractive option as luminophores for the development of luminescent solar concentrators (LSCs). In the present study, green, yellow and red emitting CdTe QDs were synthesized, characterized and proposed as luminophore of LSCs. Based on an analytical model for the concentration factor, the CdTe QDs based LSCs were optimized as a function of their geometric factor as well as the “spectrally corrected” absorption coefficient for the different LSCs luminophores. Once the optimal concentration factor for each luminophore was obtained, a COMSOL photogeneration model was used to predict the total power conversion efficiency (PCEtot) of each prospective LSC. PCEtot of 1.35%, 1.46% and 1.69% were obtained employing the green, yellow and red emitting CdTe QDs as luminophore on 5×10 cm2 planar LSCs with two perfectly reflective mirrors on the sidewalls and two COMSOL simulated silicon solar cells attached to the opposite sides.

Design and Experiment of a Quasi-Optical Mode Converter

Quasi-optical mode converter is an important component to realize the high-efficiency output for a high-power gyrotron oscillator. In this paper, design and experiments of a quasi-optical mode converter, consisting of a Denisov-type launcher and three quasi-optical mirrors, are carried out for the development of 140 GHz/TE28,8 mode gyrotron oscillator. Based on scalar diffraction method, the field distribution at the radiation aperture of the Denisov-type launcher is optimized to make the vector correlation of the aperture field with the ideal Gaussian field reach 96.2%. Based on the geometric optics method and the Gaussian beam matching method, the focusing mirror and the beam shaping mirrors were designed. A 3D full-wave analysis software Surf3D was used to obtain the field distribution on each mirror surface and the output window, which shows that the output beam with Gaussian mode content of 96.67% is obtained at the output window. The total power conversion efficiency of the quasi-optical mode converter is 93.98%. The design and experiments of the quasi-optical mode converter are performed to use the output signal of the self-developed TE28,8 mode generator as its input one under the conditions of the simulated demonstration for its conversion characteristics and the strict control for machining precision as well as the process of the converter assemble and testing. The tested results indicate that the design is in good agreement with the experiment, which is helpful for engineering design and experimental demonstration of the quasi-optical mode converter development.

Transmission Strategy for Simultaneous Wireless Information and Power Transfer with a Non-Linear Rectifier Model

Most studies determining data rate or power conversion efficiency (PCE) of simultaneous wireless information and power transfer (SWIPT) focus on ideal models for the non-linear energy harvester, or focus on simplified waveforms that carry no information. In this paper, we study SWIPT using realistic waveforms and a measurement-based energy harvesting model. For a special class of multisine waveforms carrying only information in the phase, we analyze PCE as a function of waveform design, including the impact of pre-equalization to mitigate wireless channel distortion. A balanced pre-equalizer that trades off between the peak-to-average power ratio (PAPR) and signal to noise ratio, maximizing the total PCE is proposed. The impact on the information rate of the analyzed waveforms is also presented. The results show that balanced pre-equalizers can improve the total PCE more than three times within 5% rate loss compared to the pre-equalizer that solely maximizes the signal PAPR or the capacity using the same transmit power. We also show that the maximum normalized PCE is increased by a factor of two by only allowing phase modulation to ensure the PAPR of one symbol, compared to traditional modulation schemes that carry information in both phase and amplitude to maximize spectral efficiency.

A Self-supported Graphene/Carbon Nanotube Hollow Fiber for Integrated Energy Conversion and Storage

HighlightsA novel self-supported hollow fiber with CNT array grown from graphene layer is designed and developed. The fiber provides a perfect conductive platform to deposit PANI on both inner and outer surfaces of the fiber with high mass loading.With G/CNTs/PANI hollow fiber as a common electrode, an integrated energy device with a total power conversion and storage efficiency of 2.1% is realized.

Four‐Terminal Perovskite on Silicon Tandem Solar Cells Optimal Measurement Schemes

Semitransparent perovskite solar cells (SCs) and their potential integration with silicon SCs in tandem configurations attract significantly increasing interest in the photovoltaics community. In addition to being highly spectrally complementary, these perovskite and silicon SCs have very different optimal‐performing sizes and consequently ideal measurement schemes for their integration in four‐terminal (4T) tandem configurations need to be investigated in detail. Herein, the effect of different active areas on both perovskite and silicon SCs on their photovoltaic performances is investigated. Furthermore, the commonly used filtering 4T tandem measurement scheme (named as filtered) is systematically compared with the size‐matching scheme (named as masked) demonstrating that when using the same top semitransparent perovskite and bottom silicon SCs in different measurements schemes, the total 4T tandem power conversion efficiency (PCE) can differ by more than 1%. The concepts presented here highlight the importance of optimal measurement schemes to assess 4T tandem PCE and rationalize the effect of compromise between the subcells size matching and the identification of the maximum PCE potential.

An Efficiency-Aware Cooperative Multicharger System for Photovoltaic Energy Harvesting Achieving 14% Efficiency Improvement

A high-efficiency multicharger system for photovoltaic energy harvesting is presented in this letter. The multicharger system is widely used for module-integrated converts to offer a good antipartial shading property. The proposed efficiency-aware cooperative control enhances the total power conversion efficiency of the system (ηTOT) by making chargers help each other when there is a difference between the input powers to each charger due to the partial shading. The system is implemented using a 0.5- μ m CMOS technology. The ηTOT and the power range (for ηTOT > 80%) are improved by 14% (power difference = 1.082 W) and 0.61 W (lower photovoltaic cell power = 43 mW), respectively.

Multi‐Dentate Carbazole Based Schiff Base Dyes with Chlorovinylene Group in Spacer for Dye‐Sensitized Solar Cells: A Combined Theoretical and Experimental Study.

AbstractFour new metal free organic Schiff bases employing N‐hexyl/N‐phenyl carbazole moiety as a donor, 1‐chlorobuta‐1,3‐diene as a π‐bridge and 4‐amino salicylic acid as an anchor, are designed, synthesized and investigated as photosensitizers in the dye‐sensitized solar cell (DSSC). We have studied the combined effect of the introduction of electronegative chlorine group with an additional double bond in π‐conjugation and 4‐amino salicylic acid as a tridentate anchoring group, on the optoelectronic, theoretical and photovoltaic performance of the dyes. The halogen electronegativity and strong polarization of the C–X bond represented interesting acceptor moieties for organic push–pull systems. The designed strategy leads to red‐shifted absorption maxima and reduced band gap. Density functional theory (DFT) and Time dependent density functional theory (TD‐DFT) are used to support the performance of the obtained carbazole based Schiff‐base dyes. When compared with the other three dyes, 3b exhibited the smallest band gap (2.86 eV), red‐shifted absorption spectra on TiO2 surface (453 nm) and improved nonlinear optical (NLO) properties. Among the four reported dyes, 3b exhibited the excellent photovoltaic performance, short‐circuit current density (Jsc) of 10.60 mA/cm2, open‐circuit voltage (Voc) of 0.626 V and fill factor (FF) of 70.0 %, conforming to a total power conversion efficiency of 4.3% under 1 sun light illumination due to the presence of two anchoring groups with multiple binding sites on TiO2 surface leading to efficient charge injection. NLO properties are examined theoretically and dye 3b exhibited the highest value of the first hyperpolarizability (β) amongst all four dyes which are in good agreement with exhibited highest DSSC efficiency. The present work revealed that the incorporation of electronegative chlorine group in π‐conjugation and the use of double acceptors with multiple binding sites for better adsorption on TiO2 surface are crucial to supplement the efficiency of the dye.

Continuous-wave whispering-gallery optical parametric oscillator based on CdSiP2.

Continuous-wave (cw) optical parametric oscillators (OPOs) are ideally suited for applications, for example high-resolution spectroscopy, that need coherent sources combining narrow-linewidth emission with good wavelength tunability. Here, we demonstrate for the first time cw OPOs based on a millimeter-sized whispering gallery resonator (WGR) made of cadmium silicon phosphide (CdSiP2). By employing a compact laser diode at 1.57-μm wavelength for pumping, a cw OPO with wavelength tunability from 2.3 μm to 5.1 μm is realized based on such a resonator. The oscillation thresholds are in the milliwatt range. The maximum total power conversion efficiency reaches more than 15%. The intrinsic quality factor at 1.57 μm is determined to be 3.5 × 106. This work suggests that CdSiP2 is a very promising alternative for constructing mid-infrared parametric devices.

Developing CIGS solar cells on glass-ceramic substrates

Cu(In,Ga)Se2 (CIGS) is a p-type semiconductor material and an attractive absorber for thin films solar cells due to its unique optical and electrical properties. The low cost of this technology is based on its application on ecological substrates (glass, ceramic or glass-ceramic materials), effective uses of raw materials and lower thickness of the film (range from 1.5 to 3 µm). In this work, a new glass-ceramic substrate has been developed using industrial wastes materials (recycled glass, bottom ash and fly ash from a thermal power plant) used as support in thin film solar cell technology. The CIGS absorber has been synthesized by an easy and low-cost way of preparation using the co-precipitation method. The solar cell device has been completed and fully characterized. The obtained films were characterized by X-Ray diffraction (XRD), scanning electron microscope (SEM) and electrical characterization. The short circuit current (Jsc), open circuit voltage (Voc), fill factor (FF), and total area power conversion efficiency (η) of the device are 8,11 mA/cm2, 168,2 mV, 27,6% and 0,4% respectively.