Inverted Device Research Articles

Design of DC Accumulator Charging using Backup Accumulator Based on Inverter and Converter Device

<p>The charging of DC accumulator that<br />experiences a lack of electric charge energy, usually<br />utilizes an AC input power from the PLN network. When<br />the AC input power from the PLN network is unavailable,<br />a DC power source is used from the backup DC<br />accumulator as a substitute. The research objective is to<br />design an internal DC accumulator charging using a<br />backup DC accumulator equipment based on inverter<br />and converter equipment. The charging system will use<br />input power from the backup DC accumulator to replace<br />the AC input power from the PLN network. The electric<br />voltage of the internal DC accumulator that is filled<br />(charged) is the initial condition of V<br />DC(Acu.Int.)= 8.76 Volts<br />until it reaches the normal condition of 12.05 Volts with a<br />capacity of charging current of 5 Ah (Ampere.hours)<br />absorbs electrical energy of W(Acu.Int.)<br /> = 16.45 Wh(Watt.hours). The results show that the equipment supply<br />a DC charger of 13.0 volts and PDC<br />of 21.32 watts to theinternal DC accumulator. The comparison of W<br />(Acu.Int.) to PDC produces time charging, t(charging)of 46.29 minutes</p>

Triple-junction solar cells with 39.5% terrestrial and 34.2% space efficiency enabled by thick quantum well superlattices

<h2>Summary</h2> Multijunction solar cell design is guided by both the theoretical optimal bandgap combination as well as the realistic limitations to materials with these bandgaps. For instance, triple-junction III-V multijunction solar cells commonly use GaAs as a middle cell because of its near-perfect material quality, despite its bandgap being higher than optimal for the global spectrum. Here, we modify the middle cell bandgap using thick GaInAs/GaAsP strain-balanced quantum well (QW) solar cells with excellent voltage and absorption. These high-performance QWs are incorporated into a triple-junction inverted metamorphic multijunction device consisting of a GaInP top cell, GaInAs/GaAsP QW middle cell, and lattice-mismatched GaInAs bottom cell, each of which has been highly optimized. We demonstrate triple-junction efficiencies of 39.5% and 34.2% under the AM1.5 global and AM0 space spectra, respectively, and the global efficiency is higher than previous record six-junction devices.

A New Photovoltaic Emulator Designed for Testing Low-Power Inverters Connected to the LV Grid

Assessing the performance of photovoltaic systems, particularly dedicated DC/AC inverter devices, requires the use of photovoltaic panels operating under natural environmental conditions, such as variations in solar radiation intensity, temperature and wind speed. Environmental testing is obviously very troublesome, inconvenient and limited. An alternative solution is to use a device that emulates the output photovoltaic panel curves in variable weather conditions, which allows the carrying out of all necessary tests at the laboratory. This paper presents a new photovoltaic emulator (PVE), mimicking the output characteristics of the photovoltaic panels. The proposed PVE is designed and constructed at the renewable energy laboratory for testing low-power PV inverters connected to the LV grid. A novelty of this solution is the method for shaping emulated current–voltage characteristics I–V. The concept of this method assumes autonomous regulation of slopes and shapes of emulated curve fragments. This allows us to obtain the desired shapes of the output characteristics for a wide range of both voltages and currents. The proposed PVE is not a pulse device; it belongs to linear analogue circuits. In order to confirm the assumed concept, a prototype is designed and constructed, and laboratory tests are conducted. Satisfactory results are obtained, confirming the correctness of the adopted concept. High compliance of the emulated characteristics is found in comparison to the characteristics of the selected commercial photovoltaic module. Very good results of dynamic tests and energy efficiency measurements are achieved.

Velocity Profile-Based Evaluation and Improvement of Lifetime of Power Devices in Railway Propulsion Inverters

In the work reported in this paper, the converter-level lifetime evaluation of power devices in a railway propulsion inverter is performed to assess and compare operating strategies of a railway vehicle in terms of reliability. Two groups of velocity profiles are considered for the lifetime evaluation, wherein all the velocity profiles have the same running distance and time. The first group consists of three operation velocity profiles with the same acceleration at starting and stopping, but with different cruising ranges. In the second group, three operation velocity profiles with different coasting times and acceleration values are considered. A strategy to improve the lifetimes of power devices in propulsion inverters is proposed for vehicles on a busy railway line.

Studies Regarding the Modeling of a Wind Turbine with Energy Storage

This paper presents the modeling in Matlab-Simulink of a stand-alone wind turbine system with energy storage dedicated for small power wind turbines of 3kW with a variable speed permanent magnet synchronous generator (PMSG), diode rectifier bridge, buck-boost converter, bidirectional charge controller, transformer, inverter, ac loads and energy storage devices. Are presented the general system configuration, the Simulink block diagram and the main simulated characteristics resulting from the dynamic performances during the wind speed variation.

Critical Role of Removing Impurities in Nickel Oxide on High‐Efficiency and Long‐Term Stability of Inverted Perovskite Solar Cells

AbstractThe performance enhancement of inverted perovskite solar cells applying nickel oxide (NiOx) as the hole transport layer (HTL) has been limited by impurity ions (such as nitrate ions). Herein, we have proposed a strategy to obtain high‐quality NiOx nanoparticles via an ionic liquid‐assisted synthesis method (NiOx‐IL). Experimental and theoretical results illustrate that the cation of the ionic liquid can inhibit the adsorption of impurity ions on nickel hydroxide through a strong hydrogen bond and low adsorption energy, thereby obtaining NiOx‐IL HTL with high conductivity and strong hole‐extraction ability. Importantly, the removal of impurity ions can effectively suppress the redox reaction between the NiOx film and the perovskite film, thus slowing down the deterioration of device performance. Consequently, the modified inverted device shows a striking efficiency exceeding 22.62 %, and superior stability maintaining 92 % efficiency at a maximum power point tracking under one sun illumination for 1000 h.

Critical Role of Removing Impurities in Nickel Oxide on High-Efficiency and Long-Term Stability of Inverted Perovskite Solar Cells.

The performance enhancement of inverted perovskite solar cells applying nickel oxide (NiOx ) as the hole transport layer (HTL) has been limited by impurity ions (such as nitrate ions). Herein, we have proposed a strategy to obtain high-quality NiOx nanoparticles via an ionic liquid-assisted synthesis method (NiOx -IL). Experimental and theoretical results illustrate that the cation of the ionic liquid can inhibit the adsorption of impurity ions on nickel hydroxide through a strong hydrogen bond and low adsorption energy, thereby obtaining NiOx -IL HTL with high conductivity and strong hole-extraction ability. Importantly, the removal of impurity ions can effectively suppress the redox reaction between the NiOx film and the perovskite film, thus slowing down the deterioration of device performance. Consequently, the modified inverted device shows a striking efficiency exceeding 22.62 %, and superior stability maintaining 92 % efficiency at a maximum power point tracking under one sun illumination for 1000 h.

Fabrication and Characterization of nMOS Inverters Utilizing Quantum Dot Gate Field Effect Transistor (QDGFET) for SRAM Device

This paper presents experimental results of nMOS quantum dot gate field effect transistor (QDGFET) based inverter devices for SRAM devices. A three-state inverter device was fabricated and tested with Si/SiO2 quantum dots. The work performed here builds off previous works performed with Si/SiO2 dot-based inverters which used two layers of quantum dots. This research explores multi-state SRAM device operation. A three-state (Si QDs) and a four-state (Si and Ge QDs) inverter are described, and they will allow for multistate logic devices to be utilized in everyday logic chips, which will require less devices to perform the same tasks as conventional devices, double the capacity of the device, and require less power, which will generate less of a thermal footprint. The data of the Half Cell SRAM, comprised of one access transistor and an inverter along with a capacitor, is presented here.

Atomic-Scale Imaging and Nano-Scale Mapping of Cubic α-CsPbI3 Perovskite Nanocrystals for Inverted Perovskite Solar Cells.

Colloidal synthesized cubic α-CsPbI3 perovskite nanocrystals having a smaller lattice constant (a = 6.2315 Å) compared to the standard structure, and nanoscale mapping of their surfaces are reported to achieve superior photovoltaic performance under 45-55% humidity conditions. Atomic scale transmission electron microscopic images have been utilized to probe the precise arrangement of Cs, Pb, and I atoms in a unit cell of α-CsPbI3 NCs, which is well supported by the VESTA structure. Theoretical calculation using density functional theory of our experimental structure reveals the realization of direct band to band transition with a lower band gap, a higher absorption coefficient, and stronger covalent bonding between the Pb and I atoms in the [PbI6]4- octahedral, as compared to reported standard structure. Nanoscale surface mapping using Kelvin probe force microscopy yielding contact potential difference (CPD) and conductive atomic force microscopy for current mapping have been employed on α-CsPbI3 NCs films deposited on different DMSO doped PEDOT:PSS layers. The difference of CPD value under dark and light illumination suggests that the hole injection strongly depends on the interfaces with PEDOT:PSS layer. The carrier transport through grain interiors and grain boundaries in α-CsPbI3 probed by the single-point c-AFM measurements reveal the excellent photosensitivity under the light conditions. Finally, inverted perovskite solar cells, employing α-CsPbI3 NCs film as an absorber layer and PEDOT:PSS layer as a hole transport layer, have been optimized to achieve the highest power conversion efficiency of 10.6%, showing their potential for future earth abundant, low cost, and air stable inverted perovskite photovoltaic devices.

Performance Evaluation of Si/SiC Hybrid Switch-Based Three-Level Active Neutral-Point-Clamped Inverter

In this paper, two types of Silicon (Si) IGBT and Silicon Carbide (SiC) hybrid switch (Si/SiC HyS) based three-level active neutral-point-clamped (3L-ANPC) inverter are proposed for high efficiency and low device cost. The proposed Si/SiC HyS-based 3L-ANPC inverters are compared with the full Si IGBT, full SiC MOSFET, and Si with SiC devices-based hybrid 3L-ANPC solutions on the inverter efficiency, power capacity, and device cost. It is shown that compared with the full Si IGBT 3L-ANPC solution, the inverter efficiency improvement by Si/SiC HyS is 2.4% and 1.8% at light load condition and heavy load condition, respectively. Compared to the full SiC MOSFET solution and 2-SiC MOSFETs hybrid scheme, the device cost of 2-Si/SiC HyS-based 3L-ANPC is reduced by 78% and 50% with 0.28% and 0.21% maximum inverter efficiency sacrifices. The testing results show that the proposed Si/SiC HyS-based 3L-ANPC inverter is a cost-effective way to realize high inverter efficiency. Between the two proposed Si/SiC HyS-based 3L-ANPC inverters, the 2-Si/SiC HyS-based 3L-ANPC inverter has lower device cost which makes it more suitable for cost-sensitive and high efficiency applications. While the 4-Si/SiC HyS-based 3L-ANPC inverter has higher output power capacity, making it a better candidate for high power density, high power capacity, and high efficiency applications.

Optimization based on computational analysis of lead-free inverted planar photo-voltaic device structure using halide based double perovskite material

Owing to the appealing optoelectrical, mechanical, and physical properties, configurable bandgaps, good performance on opaque devices, and low manufacturing cost, Perovskites solar cells are found to be the best alternatives for semi-transparent photo-voltaic (PV) applications. The high absorption coefficient, high carrier mobility, and long carrier diffusion length are inherent features of many organic and inorganic halide perovskite solar cells. Most of the promising perovskite materials contain Lead (Pb) and hence they are toxic. Besides toxicity issues, the stability of these perovskite structures is another key challenge in the process of its commercial production. The performance of various lead-free active PV materials was studied and identified that Cesium–Titanium Halide materials can be a suitable alternate for lead-based perovskite materials. These promising Cs2TiX6 materials have a tunable bandgap between 1.4 eV and 2.3 eV and have balanced electron and hole diffusion lengths. Most of the conventional PSC structure consists of regular planar N-I-P structure and the commercial applications of such devices are bounded due to very high J-V hysteresis and the need for high temperature during fabrication. The primary objective of this work is to optimize and develop an eco-friendly, highly efficient, Cesium-Titanium based novel inverted PV cell structure with all in-organic charge transport materials. The solar cell simulation program, SCAPS – 1D simulator, was used for conducting the numerical study and tested various device structures for obtaining maximum efficiency. The variations in the performance of PV cell structure were analyzed while using assorted absorber materials and inorganic charge transport materials. After the SCAPS-1D based simulation study, a high-performance PSC structure, FTO / MoO3 / Cs2TiBr6 / SnO2 / Au, was obtained. The proposed inverted PV cell structure can produce an excellent power conversion efficiency of 15.68 %, short-circuit current density of 16.59 mA/cm2, an open circuit voltage of 1.1 V, and a fill-factor of 85.76 %.

23.7% Efficient inverted perovskite solar cells by dual interfacial modification.

Despite remarkable progress, the performance of lead halide perovskite solar cells fabricated in an inverted structure lags behind that of standard architecture devices. Here, we report on a dual interfacial modification approach based on the incorporation of large organic cations at both the bottom and top interfaces of the perovskite active layer. Together, this leads to a simultaneous improvement in both the open-circuit voltage and fill factor of the devices, reaching maximum values of 1.184 V and 85%, respectively, resulting in a champion device efficiency of 23.7%. This dual interfacial modification is fully compatible with a bulk modification of the perovskite active layer by ionic liquids, leading to both efficient and stable inverted architecture devices.

A junction temperature estimation method of SiC power module for real time application in a traction inverter

SiC MOSFET is a kind of promising power device for transportation electrification. In electrified vehicles, SiC inverters show strong competitiveness for its high efficiency and power density, especially for high-performance applications. A SiC power module generally consists of multiple MOSFET dies and Diode dies. Junction temperature estimation of different dies in different operation points is a critical problem for practical applications. In this article, power loss of SiC devices in a motor inverter is analysed and calculated in the time scale of switching period. Subsequently, a junction temperature estimation method combining 1D foster thermal model and 3D FEM thermal model is proposed. The maximum junction temperature in a SiC power module can be estimated with low computational burden. Working boundary with varying sine current amplitude and switching frequency can also be obtained for real-time control of motor inverters. The effectiveness and practicability of the proposed method is verified with transition simulation.

The Effect of Cs/FA Ratio on the Long‐Term Stability of Mixed Cation Perovskite Solar Cells

Formamidinium lead iodide (FAPbI3) is ideal for highly efficient and operationally stable perovskite solar cells (PSC). However, a primary challenge for FAPbI3 PSC is to suppress the phase transition from the photoactive black phase into the yellow nonperovskite δ‐phase. The preparation of Cs‐containing mixed FAPbI3 perovskite by cation stoichiometric engineering is demonstrated and the influence of the Cs/FA ratio on its phase stability and device performance is discussed. By exploring the optimal ratio of Cs and FA cations in Cs x FA1−x Pb(I0.94Br0.06)3 perovskite, an inverted planar device with Cs0.17FA0.83Pb(I0.94Br0.06)3 composition shows the best power conversion efficiency (PCE) of 16.5% in an active area of 1.08 cm2. More importantly, the Cs0.17FA0.83Pb(I0.94Br0.06)3 perovskite photoactive layer showed remarkable long‐term stability, maintaining 88.1% of its initial efficiency for 1128 h in the presence of moisture and oxygen and without any encapsulation. The excellent long‐term stability is found to originate from the appropriate tolerance factor and low thermodynamic decomposition energy, which underpins the strong potential for the commercialization of Cs‐containing mixed FAPbI3 PSCs.

Perovskite Metal–Oxide–Semiconductor Structures for Interface Characterization

AbstractPerovskite solar cells (PSCs) are one of the most promising photovoltaic technologies. Amongst several challenges, developing and optimizing efficient electron transport layers that can be up‐scaled still remains a massive task. Admittance measurements on metal–oxide–semiconductor (MOS) devices allow to better understand the optoelectronic properties of the interface between perovskite and the charge carrier transport layer. This work discloses a new pathway for a fundamental characterization of the oxide/semiconductor interface in PSCs. Inverted MOS structures, that is, glass/fluorine‐doped tin oxide/tin oxide (SnO2)/perovskite are fabricated and characterized allowing to perform a comparative study on the optoelectronic characteristics of the interface between the perovskite and sputtered SnO2. Admittance measurements allow to assess the interface fixed oxide charges (Qf) and interface traps density (Dit), which are extremely relevant parameters that define interface properties of extraction layers. It is concluded that a 30 nm thick SnO2 layer without annealing presents an additional recombination mechanism compared to the other studied layers, and a 20 nm thick SnO2 layer without annealing presents the highest positive Qf values. Thus, an effective method is shown for the characterization of the charge carrier transport layer/perovskite interface using the analysis performed on perovskite‐based inverted MOS devices.

Recent progress of oxide-TFT-based inverter technology

Oxide semiconductor-based thin-film transistor (oxide-TFT) technology have gained significant attention since the innovation of n-channel oxide-TFT using ZnO and amorphous In–Ga–Zn–O (a-IGZO) channels because of their superior device properties including excellent electrical property such as high TFT mobility over >10 cm2/Vs and the low-cost manufacturability originating from the low-temperature processability. Already, n-channel a-IGZO-TFT is widely employed as a TFT pixel switching backplane for several high-performance active-matrix flat-panel displays, and oxide-TFT technology to date is well acknowledged as the best TFT technology for future device applications in the wide range area of electronics such as sensors, Internet of things (IoT), energy-harvesting, medical/bio-interface device, etc. Therefore, the development of large-scale circuit beyond discrete TFT device level becomes increasingly important and is vital to advance the next stage of oxide-TFT technology. In particular, developing oxide-TFT-based inverter device technology is the key for developing several digital and analog circuits. In this paper, the recent progress and challenges in oxide-TFT-based inverter technology, including unipolar NMOS, PMOS, CMOS, and CMOS-like inverters using ambipolar oxide-TFT, are reviewed.

Perovskite Passivation with a Bifunctional Molecule 1,2‐Benzisothiazolin‐3‐One for Efficient and Stable Planar Solar Cells

Even though the perovskite material itself has a high defect tolerance compared with other semiconductors, the defects existing at grain boundaries (GBs) or the surface still cause high densities of the trap state which impair the efficiency and stability of perovskite solar cells (PSCs). Herein, the small molecule 1,2‐benzisothiazolin‐3‐one (BIT) is investigated to passivate the defects at the GBs and surface of perovskite films. The results reveal that the BIT molecule belongs to a type of bifunctional species, which functions as cations and anions to passivate the perovskite surface. The BIT passivation generates lower formation energy and a more stable perovskite structure, resulting in improved performance and stability of the PSCs. The power conversion efficiency (PCE) of the optimized inverted photovoltaic device reaches 21.83%. Meanwhile, high photostability is achieved for PSCs with an efficiency drop of less than 10% under continuous light illumination over 500 h.

Efficient inverted organic light-emitting devices using a charge-generation unit as electron-injection layers

Efficient electron injection from cathode to electron transport layer is generally required to realize high-performance inverted organic light-emitting devices (IOLEDs). In this work, highly efficient IOLEDs are developed by employing a non-doped charge-generation unit of 1,4,5,8,9,11-hexaazatriphenylene-hexacarbonitrile (HAT-CN)/Al/LiF as electron-injection layers (EILs). The ultraviolet photoelectron spectroscopy (UPS) shows that the insertion of HAT-CN layer reduces the work function of EILs by 0.21 eV. Combined with the current-voltage characteristics of electron-only devices, the role of the HAT-CN layer in promoting electron injection is confirmed. What's more, the double EILs device with Rubrene as a probe verifies the strong hole blocking ability of HAT-CN/Al/LiF. Based on the EILs, the inverted blue phosphorescent OLEDs with a maximum current efficiency of 29.4 cd/A are realized. The excellent performance proves the superiority of HAT-CN/Al/LiF as EILs. Working diagrams of CGU as EILs.In this work, highly efficient IOLEDs are developed by employing a non-doped CGU of HAT-CN/Al/LiF as EILs. The EILs show strong electron injection and hole blocking capabilities. •The charge generation unit as the electron injection layers greatly improves the injection of electrons. •The non-doped electron injection layers improves the stability and repeatability of the devices. •Based on the EILs, the inverted blue OLEDs with the maximum current efficiency of 29.4 cd/A and a maximum EQE of 14.6% are realized.

Binary-mixed organic electron transport layers for planar heterojunction perovskite solar cells with high efficiency and thermal reliability

The optimal electron transport layer (ETL) is a crucial component in the inverted perovskite solar cells (PSCs) for achieving high photovoltaic performance and device stability. We herein address the alloy ETL strategy, which incorporates a non-fullerene small molecule, ITIC-4F, into the fullerene-based ETL to optimize the electron-selective interfacial properties of CH3NH3PbI3-based inverted PSCs. The alloy ETL exhibited tailored energy level alignment at the interface of perovskite and ETL, so the electron-extraction/recombination behavior is greatly improved. Also, the hydrophobic surface of the alloy ETL effectively impedes not only moisture invasion but also morphological deterioration under continuous operation, so the resultant CH3NH3PbI3-based inverted device modified with the alloy ETL exhibited superior power conversion efficiency (PCE) up to 19.99%, with a negligible hysteresis. The alloy ETL-based PSCs also achieves 25.1% efficiency under indoor lighting condition, which promises a feasible design strategy of interfacial optimization in high-performance PSCs using organic semiconductors.

Phenyl Ethylammonium Iodide introduction into inverted triple cation perovskite solar cells for improved VOC and stability

Abstract The efficiency of more than 25% in organic-inorganic hybrid perovskite solar cells has made them very attractive in the pursuit of cheaper alternatives to Si-based devices. However, the stability of the perovskite solar cells was challenging, given their high susceptibility to moisture. Very few reports have emerged in this regard that investigated the influence of introducing large cations into a triple cation perovskite (TC-PVS), with several studies limited to single and dual cation perovskites. Further, the crystallization of TC-PVS on a polymer surface such as PEDOT is not straightforward, and their inclusion in inverted solar cell devices was limited. In this work, we investigated the impact of incorporating Phenyl ethyl ammonium cation into FAMACs triple cation composition. We demonstrated improvements in the crystallinity and more uniform coverage with little to no pinholes and smooth morphology for an optimum PEA amount of 1.67% in the precursor solution. The superior morphology, along with a passivation effect from a quasi 2D phase, led to increased photoluminescence and minority carrier lifetimes. Corresponding inverted photovoltaic devices prepared with PEA showed increased open-circuit voltage from 0.89 V for a control sample to 0.95 V for 1.67% PEA and 0.98 V for 5% PEA, doped devices in an inverted configuration. The efficiency, as a result, increased from 11.27% for a control device to 14.85% for a 1.67% PEA doped device. Further, PEA doped devices showed improved operational and thermal stability attributed to the higher moisture tolerance and light-soaking ability of the PEA doped TC-PVS compared to the undoped TC-PVS.