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Highly Efficient Thermally Co-evaporated Perovskite Solar Cells and Mini-modules
摘要： Although small-area perovskite solar cells (PSCs) have reached remarkable power conversion efficiencies (PCEs), their scalability still represents one of the major limits toward their industrialization. For the first time, we prove that PSCs fabricated by thermal co-evaporation show excellent scalability. Indeed, our strategy based on material and device engineering allowed us to achieve the PCEs as high as 20.28% and 19.0% for 0.1 and 1 cm2 PSCs and the record PCE value of 18.13% for a 21 cm2 mini-module.
关键词： thermal co-evaporation,scalability,power conversion efficiency,mini-modules,perovskite solar cells
更新于2025-09-23 15:21:01
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Narrowing the Band Gap: The Key to High-Performance Organic Photovoltaics
摘要： Organic photovoltaics (OPVs) have attracted considerable attention in the last two decades to overcome the terawatt energy challenge and serious environmental problems. During their early development, only wide-band-gap organic semiconductors were synthesized and employed as the active layer, mainly utilizing photons in the UV?visible region and yielding power conversion e?ciencies (PCEs) lower than 5%. Afterward, considerable e?orts were made to narrow the polymer donor band gap in order to utilize the infrared photons, which led to the enhancement of the PCE from 5% to 12% in about a decade. Since 2017, the study of narrow-band-gap non-fullerene acceptors helped usher in a new era in OPV research and boosted the achievable the PCE to 17% in only 3 years. In essence, the history of OPV development in the last 15 years can be summarized as an attempt to narrow the band gap of organic semiconductors and better position the energy levels. There are multiple bene?ts of a narrower band gap: (1) considerable infrared photons can be utilized, and as a result, the short-circuit current density can increase signi?cantly; (2) the energy o?set of the lowest unoccupied molecular orbital energy levels or highest occupied molecular orbital energy levels between the donor and acceptor can be reduced, which will reduce the open-circuit voltage loss by minimizing the loss caused by the donor/acceptor charge transfer state; (3) because of the unique molecular orbitals of organic semiconductors, the red-shifted absorption will induce high transmittance in the visible region, which is ideal for the rear subcells in tandem-junction OPVs and transparent OPVs.
关键词： Organic photovoltaics,narrow-band-gap,non-fullerene acceptors,power conversion efficiencies,polymer donors
更新于2025-09-23 15:21:01
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Improvement of Power Conversion Efficiency of Quantum Dot-Sensitized Solar Cells by Doping of Manganese into a ZnS Passivation Layer and Cosensitization of Zinc-Porphyrin on a Modified Graphene Oxide/Nitrogen-Doped TiO <sub/>2</sub> Photoanode
摘要： It is vital to acquire power conversion efficiencies comparable to other emerging solar cell technologies by making quantum dot-sensitized solar cells (QDSSCs) competitive. In this study, the effect of graphene oxide (GO), nitrogen, manganese, and a porphyrin compound on the performance of QDSSCs based on a TiO2/CdS/ZnS photoanode was investigated. First, adding GO and nitrogen into TiO2 has a conspicuous impact on the cell efficacy. Both these materials reduce the recombination rate and expand the specific surface area of TiO2 as well as dye loading, reinforcing cell efficiency value. The maximum power conversion efficiency of QDSSC with a GO N-doped photoelectrode was 2.52%. Second, by employing Mn2+ (5 and 10 wt %) doping of ZnS, we have succeeded in considerably improving cell performance (from 2.52 to 3.47%). The reason for this could be for the improvement of the passivation layer of ZnS by Mn2+ ions, bringing about to a smaller recombination of photoinjected electrons with either oxidized dye molecules or electrolyte at the surface of titanium dioxide. However, doping of 15 wt % Mn2+ had an opposite effect and somewhat declined the cell performance. Finally, a Zn-porphyrin dye was added to the CdS/ZnS by a cosensitization method, widening the light absorption range to the NIR (near-infrared region) (>700 nm), leading to the higher short-circuit current density (JSC) and cell efficacy. Utilizing an environmentally safe porphyrin compound into the structure of QDSSC has dramatically enhanced the cell efficacy to 4.62%, which is 40% higher than that of the result obtained from the TiO2/CdS/ZnS photoelectrode without porphyrin coating.
关键词： graphene oxide,nitrogen doping,manganese doping,quantum dot-sensitized solar cells,cosensitization,Zn-porphyrin,power conversion efficiency
更新于2025-09-23 15:21:01
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Passivation of defects in inverted perovskite solar cells by imidazolium-based ionic liquid
摘要： During perovskite film preparation, defects in the film are almost impossible to avoid because of the migration of the halide ions, which is detrimental to achieve high-quality film. In general, the introduction of additive is an effective strategy to control the film morphology and to reduce the defect density. Here, a representative and simplest ionic liquid, 1-methyl-3-propylimidazolium bromide (MPIB), is selected as an additive due to its high conductivity and lone-pair electron in its cation group. Remarkably, the adding of MPIB additive into the perovskite film improves the power conversion efficiency (PCE) from 15.9% of pristine device to 18.2%. With the help of characterization analysis of scanning electron microscopy, X-ray photoelectron spectroscopy, Fourier transform infrared spectrometer, etc., two contributions of MPIB additive are addressed: (1) the major one is the passivation of the uncoordinated Pb2+ to reduce the defects in the perovskite film due to the lone-pair electron in its cation group, and (2) the secondary one is beneficial to promote crystal growth to improve the film quality. Hence, this work provides an easy approach to achieve high-performance perovskite solar cell via passivation of the uncoordinated Pb2+ in the perovskite film due to the lone-pair electron in the cation group.
关键词： MPIB,ionic liquid,perovskite solar cells,power conversion efficiency,defect passivation
更新于2025-09-23 15:21:01
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Conjugated side-chains engineering of polymer donor enabling improved efficiency for polymer solar cells
摘要： Generally, molecular optimization is widely used to fine-tune the absorption features and energy levels of photovoltaic materials to improve their photovoltaic performance for polymer solar cells (PSCs). In this work, we demonstrate an example that the morphological properties can be effectively optimized by conjugated side-chains engineering on benzo[1,2-b:4,5-b']dithiophene (BDT) unit. The polymer donors PBNT-S with alkylthio-thienyl substitution and PBNP-S with alkylthio-phenyl substitution have identical absorption spectra and energy levels, while exhibit significantly different morphological properties when blended with nonfullerene acceptor Y6. The PBNT-S:Y6 blend shows obviously over crystallinity with excessive domain sizes, while the PBNP-S:Y6 blend realizes better nanoscale phase separation. As a result, a notable power conversion efficiency (PCE) of 14.31% with a high fill factor (FF) of 0.694 is achieved in the PBNP-S:Y6-based device, while the PBNT-S:Y6-based device yields a moderate PCE of 11.10% and a relatively low FF of 0.605. Additionally, PBNP-S shows great potential in semitransparent PSCs, that the PBNP-S:Y6-based semitransparent PSC achieves an outstanding PCE of 11.86%, with an average visible transmittance of 24.3%. The results demonstrate a feasible strategy to manipulate the morphological properties of blend film via rational molecular optimization to improve the photovoltaic performance.
关键词： polymer solar cells,morphological properties,conjugated side-chains engineering,semitransparent PSCs,power conversion efficiency
更新于2025-09-23 15:21:01
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Light-Emitting Diode Power Conversion Capability and CO2 Fixation Rate of Microalgae Biofilm Cultured Under Different Light Spectra
摘要： Microalgae biofilm-based culture has attracted much interest due to its high harvest efficiency and low energy requirements. Using light-emitting diodes (LEDs) as light source for microalgae culture has been considered as a promising choice to enhance the economic feasibility of microalgae-based commodities. In this work, the LED power conversion capability and CO2 fixation rate of microalgae biofilms (Chlorella ellipsoidea and Chlorella pyrenoidosa) cultured under different light spectra (white, blue, green and red) were studied. The results indicated that the power-to-biomass conversion capabilities of these two microalgae biofilms cultured under blue and white LEDs were much higher than those under green and red LEDs (C. ellipsoidea: 32%–33% higher, C. pyrenoidosa: 34%–46% higher), and their power-to-lipid conversion capabilities cultured under blue LEDs were 61%–66% higher than those under green LEDs. The CO2 fixation rates of these two biofilms cultured under blue LEDs were 13% and 31% higher, respectively, than those under green LEDs. The results of this study have important implications for selecting the optimal energy-efficient LEDs using in microalgae biofilm-based culture systems.
关键词： biofilm-based cultivation,microalga,light spectrum,power conversion capability,CO2 fixation rate
更新于2025-09-23 15:21:01
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GaN Transistors for Efficient Power Conversion || Modeling and Measurement of GaN Transistors
摘要： The previous chapter focused on the layout parasitics that are important when using GaN transistors, and showed methods of minimizing these parasitics for layouts with various levels of complexity. In this chapter, the focus will be on how best to understand and predict the actual in-circuit behavior of the GaN transistors once the layout has been completed. Although measurement and modeling are very different, they complement each other when attempting to better understand real-world behavior. The initial discussion will focus on the electrical and thermal modeling of GaN transistors, and conclude with discussion of the requirements and limitations when directly measuring in-circuit behavior.
关键词： power conversion,electrical modeling,GaN transistors,measurement,modeling,thermal modeling
更新于2025-09-23 15:21:01
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GaN Transistors for Efficient Power Conversion || Hard-Switching Topologies
摘要： In hard-switching converters, the transistors are turned on and off rapidly, while there is voltage across – and current through – the drain and source of the device. These switching transitions lead to significant power losses during the switching event. The main metrics of any converter performance are: (a) efficiency, where higher is better, (b) size, where smaller is better, and (c) cost, where lower is better. Efficiency can be increased through improvements in the switching (dynamic) and conduction (static) characteristics of the devices, thereby allowing higher switching frequencies to be used. This, in turn, leads to a size reduction, which also can lead to lower cost. In this chapter, hard-switching topologies will be reviewed and we will look at how the superior properties of GaN transistors yield significant performance improvements.
关键词： power conversion,hard-switching,efficiency,GaN transistors,switching losses
更新于2025-09-23 15:21:01
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GaN Transistors for Efficient Power Conversion || Resonant and Soft-Switching Converters
摘要： The previous chapter addressed the application of GaN transistors in hard-switching power converters, and we demonstrated the benefits that GaN transistors provide – as compared to state-of-the-art silicon power MOSFETs. In this chapter, we discuss the fundamentals of resonant and soft-switching applications and evaluate the superior performance capabilities of GaN transistors over silicon MOSFETs in these applications. The chapter will conclude with a design example comparing GaN transistors and Si MOSFETs in an isolated, high-frequency 48 V intermediate bus converter (IBC) with a 12 V output, utilizing a resonant topology operating at 1.2 MHz.
关键词： power conversion,GaN transistors,resonant converters,soft-switching,silicon MOSFETs
更新于2025-09-23 15:21:01
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GaN Transistors for Efficient Power Conversion || RF Performance
摘要： The main focus to this point in the book has been the switching capabilities of GaN transistors. Now, the RF capabilities of these same GaN transistors and, in particular, enhancement-mode transistors will be examined, highlighting specific RF applications that can benefit from their adoption.
关键词： power conversion,RF performance,GaN transistors,RF applications,enhancement-mode
更新于2025-09-23 15:21:01