Voltage Efficiency Research Articles

Continuous wave GaSb-based interband cascade lasers with hybrid cladding layers operated at room temperature and above

We report the preliminary demonstration of continuous wave (cw) GaSb-based interband cascade lasers (ICLs) with hybrid cladding layers at high temperatures up to 80 °C near a wavelength of 3.72 μm. These ICLs have narrow-ridge widths of 7–11 μm with improved thermal dissipation compared to broad-area devices. They delivered a cw output power of more than 30 mW/facet at 20 °C and had a cw threshold current density of 270 A/cm2 with a voltage efficiency of 78% at 300 K. The obtained voltage efficiency of 78% is the highest ever reported among cw GaSb-based ICLs at room temperature, indicating an advantage of efficient carrier transport in the ICL with the hybrid cladding layers. The dependence of device performance on the narrow-ridge width and cavity length was investigated. The results suggested ways to further improve future devices.

A High-Performance Polyimide Composite Membrane with Flexible Polyphosphazene Derivatives for Vanadium Redox Flow Battery.

A sulfonated polyimide, S-F-abSPI, with alkyl sulfonic acid side chains, and a polyphosphonitrile derivative, poly[4-methoxyphenoxy (4-fluorophenoxy) phosphazene] (PFMPP), were designed and synthesized. Composite modification of the S-F-abSPI membrane was carried out using PFMPP, resulting in the preparation of composite membranes with different composite ratios, which were then subjected to performance testing and characterization. Experimental results revealed a significant enhancement in the proton conductivity of the S-F-abSPI membrane, reaching 0.116 S cm-1, slightly higher than that of the N212 membrane. The S-F-abSPI/1% PFMPP composite membrane exhibited the optimal comprehensive performance, with a surface resistance as low as 0.54 Ω cm2, comparable to that of the N212 membrane. At a high current density of 200 mA cm-2 during charge-discharge, the composite membrane achieved a voltage efficiency (VE) of 83.12% and an energy efficiency (EE) of 81.95%. Cycling tests over 200 cycles demonstrated the composite membrane's excellent long-term cycling stability. The alkyl sulfonic acid side chains enhanced the proton conductivity of the membrane, while electrostatic potential distribution calculations indicated strong interactions between PFMPP and the base membrane, enhancing the membrane's mechanical strength, reducing vanadium ion permeability, and improving chemical stability and vanadium ion selectivity. This composite membrane holds promise for high-performance VRFB applications.

Isolated FeN3 sites anchored hierarchical porous carbon nanoboxes for hydrazine‐assisted rechargeable Zn‐CO2 batteries with ultralow charge voltage

AbstractZn‐CO2 batteries (ZCBs) are promising for CO2 conversion and electric energy release. However, the ZCBs couple the electrochemical CO2 reduction (ECO2R) with the oxygen evolution reaction and competitive hydrogen evolution reaction, which normally causes ultrahigh charge voltage and CO2 conversion efficiency attenuation, thereby resulting in ~90% total power consumption. Herein, isolated FeN3 sites encapsulated in hierarchical porous carbon nanoboxes (Fe‐HPCN, derived from the thermal activation process of ferrocene and polydopamine‐coated cubic ZIF‐8) were proposed for hydrazine‐assisted rechargeable ZCBs based on ECO2R (discharging process: CO2 + 2H+ → CO + H2O) and hydrazine oxidation reaction (HzOR, charging process: N2H4 + 4OH− → N2 + 4H2O + 4e−). The isolated FeN3 endows the HzOR with a lower overpotential and boosts the ECO2R with a 96% CO Faraday efficiency (FECO). Benefitting from the bifunctional ECO2R and HzOR catalytic activities, the homemade hydrazine‐assisted rechargeable ZCBs assembled with the Fe‐HPCN air cathode exhibited an ultralow charge voltage (decreasing by ~1.84 V), excellent CO selectivity (FECO close to 100%), and high 89% energy efficiency. In situ infrared spectroscopy confirmed that Fe‐HPCN can generate rate‐determining *N2 and *CO intermediates during HzOR and ECO2R. This paper proposes FeN3 centers for bifunctional ECO2R/HzOR performance and further presents the pioneering achievements of ECO2R and HzOR for hydrazine‐assisted rechargeable ZCBs.

Preparation of Vanadium (3.5+) Electrolyte by Hydrothermal Reduction Process Using Citric Acid for Vanadium Redox Flow Battery

In this study, vanadium (3.5+) electrolyte was prepared for vanadium redox flow batteries (VRFBs) through a reduction reaction using a batch-type hydrothermal reactor, differing from conventional production methods that utilize VOSO4 and V2O5. The starting material, V2O5, was mixed with various concentrations (0.8 M, 1.2 M, 1.6 M, 2.0 M) of citric acid (CA) as the reducing agent and stirred for 60 min at 90 °C using a hot plate to ensure complete dispersion in the solution. The resulting solution was subsequently subjected to a hydrothermal reduction reaction (HRR) furnace at 150 °C for 24 h to generate vanadium (3.5+). The mixed states of the produced vanadium (3+) and vanadium (4+) were confirmed using UV-vis spectroscopy. The electrochemical properties of the electrolyte were investigated through cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS), revealing that the optimal concentration of the CA was 1.6 M. The current efficiency, energy efficiency, and voltage efficiency of the electrolyte produced via the HRR process was compared with that prepared using VOSO4 in charge and discharge experiments. The results demonstrate that the HRR process yields an enhanced electrolyte across all efficiency metrics produced through the given improved performance in all efficiencies. These findings indicate that the HRR process using citric acid can facilitate the straightforward preparation of vanadium (3.5+) electrolyte, making it suitable for large-scale production.

Enhancing hole-transport efficiency in (CH3NH3)2CuClxBr4-x perovskite solar cells through functionalization of multi-walled carbon nanotubes

This study addresses the conductivity limitation of conventional hole-transporting layers (HTLs) like Spiro-OMeTAD in perovskite solar cells. We integrate functionalized multi-walled carbon nanotubes (MWCNTs) into Spiro-OMeTAD and examine the impact of chemical oxidation/functionalization of MWCNTs on their application in perovskite solar cells. Various ratios of H2SO4/HNO3 mixture were employed to functionalize MWCNTs, with FTIR analysis confirming functional group attachments on the nanotube walls. Raman spectroscopy was utilized to analyze defect formation in the MWCNTs, while FESEM images displayed both the tubular structure and morphological alterations resulting from functionalization. XRD analysis was conducted to examine the structural variances resulting from different functionalization ratios. A lead-free copper-based perovskite (CH3NH3)2CuBr4-xClx (x = 0.5), synthesized via a straightforward solution method, served as the active material for solar cells. The XRD assessment of the active material confirmed perovskite formation, with morphological analysis revealing a layered structure. Diffuse Reflectance Spectroscopy (DRS) measurements yielded a bandgap of approximately 1.86 eV for the perovskite. Dark I–V measurements were executed for Spiro-OMeTAD films incorporated with pure and functionalized MWCNTs, showcasing improved conductivity attributed to charge carrier conduction via defect passivation. Hybrid solar cells were fabricated with structures such as TiO2/(CH3NH3)2CuBr4-xClx (x = 0.5)/Spiro-OMeTAD/Ag, and TiO2/(CH3NH3)2CuBr4-xClx (x = 0.5)/functionalized MWCNTs/Spiro-OMeTAD/Ag. These cells demonstrated enhanced stability, retaining over 65 % of their initial efficiency after 10 days of storage, attributed to improved moisture permeability inferred from contact angle measurements and XRD analysis. Photovoltaic characterization revealed significant improvements in fill factor (∼70 %), short-circuit current density (2.94 mA), open-circuit voltage (0.70 V), and power conversion efficiency (PCE) (1.6 %) for the FTO/TiO2/(CH3NH3)2CuCl0·5Br3.5/Spiro-MWCNT-1/Ag device.

Benchmarking Performance Indices of Electrochemical CO2 Reduction to Ethylene Based on Prospective Life Cycle Assessment for Negative Emissions.

To mitigate global warming to the most ambitious targets, it is necessary to remove CO2 from the atmosphere and reduce fossil fuels use. The electrochemical conversion of CO2 to ethylene (C2H4) as a basic chemical is a promising technology that meets both requirements; however, its life cycle CO2 emissions remain inconclusive because of varying assumptions in the performance indices. This study aimed to set benchmarks for the four most sensitive indices to achieve -0.5 t-CO2/t-C2H4 by calculating net greenhouse gas (GHG) emissions through a prospective life cycle assessment of a model system including CO2 capture, CO2 enrichment, electrochemical conversion, CO2 recycling, and cryogenic separation. As a result, the electrochemical conversion process was the hotspot of life cycle emissions, and representative benchmarks were determined as follows: cell voltage, 3.5 V; C2H4 Faraday efficiency, 70 %; conversion rate, 20 %; and electrochemical CO2 recycling energy, 2.2 GJ/t-CO2. The gaps between the benchmarks and current top data of cell voltage and Faraday efficiency were <10 %, and suppressing the performance degradation for up to one year was found to be a critical requirement. These results can direct research towards the development of a year-round stable system, rather than further improving the performance indices.

Illustrating the influence of anodic/cathodic second-phases on dissolution mode via Mg–Ca–Sn alloy anodes for primary Mg-air cells

Two second-phases with an opposite potential difference to the α-Mg matrix may affect the discharge mechanism of magnesium (Mg) anodes for primary Mg-air cells through different micro-galvanic behaviors. Herein, using Mg–Ca-xSn alloys anode with Mg2Ca and CaMgSn phases, we investigated their influence on the dissolution mode of Mg-anode during discharge state via in-situ scanning vibrating electrode technique (SVET) technology. Firstly, the peak surface positive potential of Mg–1Ca alloy only containing Mg2Ca phase and Mg–1Ca–1Sn alloy with CaMgSn/Mg2Ca phase increases multiplied by 10 during the discharge process compared to that of OCP, exhibiting accelerated anodic substrate dissolution. Moreover, Mg2Ca-phases can be attacked firstly while promoting the discharge of the α-Mg matrix surrounding them, leading to the preferential dissolution of grain boundaries and “chunk effects (CE)” occurrence. More CaMgSn/α-Mg couples are activated to form dispersed micro-galvanic cell islands, which also boosts the dissolution of the α-Mg matrix but reduces the area of high-intensity dissolution reaction due to CaMgSn acting as a cathode. However, excessive CaMgSn-phase generally fails to discharge effectively to reduce anode efficiency, although it can improve the self-peeling capacity of the film layer through physical detachment; in addition, with Sn content increasing to 3 wt%, the open circuit voltage of Mg–1Ca–3Sn significantly declines. Mg–1Ca-0.2Sn exhibits the highest cell voltage and anodic efficiency by introducing a tiny amount of dispersed short rod-like CaMgSn, due to the adjusted dissolution mode, enhanced electrochemical activity and inhibited CE. Finally, our study provides a universal mechanism for fabricating Mg-anode with high performance via phase composition modulation.

An “Ion Harvester” Battery in Soil Empowered by a Microfluidic Pump and Interlayer Confinement within Micro‐Swiss‐Rolls

AbstractA significant challenge arises in powering distributed tiny sensors that gather high‐resolution soil data are crucial for advancing digital and geospatial technologies in the field. Traditional batteries and solar cells are unsuitable due to size mismatches. Microbial fuel cells lack stability in delivering constant power. Soil naturally contains redox‐active ions, such as Zn2+ and Mn2+, which can be harvested and utilized for electrochemical energy storage. To facilitate access to soluble ions, a microfluidic pump based on micro‐Swiss‐roll structures via micro‐origami is developed. Spontaneous capillary flow allows for efficient liquid extraction. The micro‐Swiss‐roll architecture shows significant improvements in redox reversibility and charge transfer within micrometer‐thick interlayer space. Notably, the interference of Zn0/2+ and Mn(II)/Mn(IV) reactions is suppressed. Consequently, the battery using a micro‐Swiss‐roll electrode shows high voltage and energy efficiency at high currents up to 10 µA, with cycling stability of 300 times. A twin‐micro‐Swiss‐roll architecture of 0.385 ± 0.006 mm2 is used for energy storage in wet soil, yielding over 40 times more energy as compared to soil‐microbial fuel cells. A conceptual demonstration of an integrated irrigation water sensor and micro‐Swiss‐roll battery highlights the potential of microbattery development in addressing the critical challenge of powering tiny sensors in the soil.

Comparative Analysis Using the SCAPS-1D Software on the Stability and Toxcity of the Perovskites FAPbI&lt;sub&gt;3&lt;/sub&gt;, and FASnI&lt;sub&gt;3&lt;/sub&gt;

Hybrid organometallic perovskites such as FAPbI3 (formamidinium lead iodide) and FASnI3 (formamidinium tin iodide) are recognized as promising materials for the next generation of high-efficiency solar cells. FAPbI3 is particularly valued for its stability and excellent optoelectronic properties. However, the toxicity of lead and the resulting environmental concerns drive the search for alternatives like FASnI3, where tin, a less toxic and more abundant element, replaces lead, which is the objective of this study. The lead-free structure simulated using SCAPS-1D software is as follows: FTO/TiO2/FASnI3/Spiro-OMeTAD/Ag. The research presented here shows that optimizing several parameters can achieve a power conversion efficiency (PCE) of 22.49%. We opted for TiO2 as the ETL due to its wide bandgap (~3.2 eV for the anatase phase), which effectively blocks holes and prevents their recombination with electrons, thus promoting better charge separation. Moreover, the favorable energy level alignment of TiO2 with the perovskites facilitates the transfer of electrons to the silver (Ag) electrode. For the HTL, we chose Spiro-OMeTAD, whose valence band level is well aligned with that of the perovskites, making it easier to extract holes to the upper silver electrode. Using the SCAPS-1D simulator, we then compared the electrical and optical properties of the devices, focusing on key parameters such as short-circuit current density (Jsc), open-circuit voltage (Voc), fill factor (FF), and power conversion efficiency (PCE). The best results obtained after optimizing the aforementioned parameters are Jsc of 30.65 mA/cm2 , Voc of 0.8469 V, FF of 86.63%, and PCE of 22.49%. Additionally, the structure studied in this article could be a good candidate for future research on lead-free perovskite solar cells.

Structural Modeling of Fluorinated Quinoxaline Core–Based Chromophores for Efficient Photovoltaic Materials: A DFT Study

ABSTRACTHerein, a series of fluorinated quinoxaline core–based chromophores (MTH1‐MTH6) with A1–π–A2–π–A1 configuration was designed by structural modulation of end‐capped acceptors in MTHR. The quantum chemical calculations were accomplished at MPW1PW91/6‐311G(d,p) functional to explore optoelectronic and photovoltaic properties of these designed compounds. The findings revealed that all the derivatives exhibited narrow band gap (Egap = 2.163–2.666 eV) with red shift spectra (610.24–766.944 eV in chloroform) as compared with MTHR. The designed compounds exhibited comparable open‐circuit voltage (Voc) and higher power conversion efficiencies (PCEs) as compared with the MTHR. Among the entitled chromophores, MTH1 was found to be a promising chromophore for organic solar cells (OSCs) owning to its lowest Egap (2.163 eV) with highest absorption peak (766.944 nm in chloroform and 717.709 nm in gaseous phase). The aforementioned findings indicate that molecular engineering of chromophores with extended acceptors enhances photovoltaic response, and this motivates researchers to develop highly effective photovoltaic devices.

Investigation on indium concentration in two-terminal tandem indium gallium nitride solar cells by SCAPS-1D

Indium gallium nitride (InGaN) thin-film solar cell is a promising photovoltaic (PV) device. InGaN’s bandgap is tunable from 0.7 to 3.4 eV and it exhibits a high absorption coefficient exceeding 105 cm−1. Besides, InGaN solar cells can be used in tandem configuration, to effectively absorb the solar spectrum. Previous works found that increased indium (In) concentration leads to inverse relationship between open-circuit voltage (Voc) and power conversion efficiency (PCE) of the solar cell. This leads to deleterious device performance. This study aims to assess the performance of two-terminal InGaN tandem solar cells using SCAPS-1D simulation software. The findings revealed maximum short-circuit current density (Jsc) of 26.19 mA cm−2, open-circuit voltage (Voc) of 2.13 V, fill factor (FF) of 89.68%, and PCE of 30.17% from the tandem device. The results indicate that higher In concentration enhances light absorption and the overall PCE, with tandem cells outperforming single-junction cells. This study makes a valuable contribution to the advancement of high-efficiency solar technology based on InGaN.

Atomically dispersed ruthenium single-atom alloy catalysts enabling efficient iodide oxidation reaction electrolysis in acidic media

Single-atom catalysts exhibit immense potential across diverse reactions, yet their synthesis and stability in acidic environments pose significant challenges. Herein, we introduce a facile one-step hydrothermal approach to fabricate Ru single-atom alloy catalysts (Ru SAAC) through the reaction of Ru and Ti precursors, followed by annealing in an argon atmosphere. Analysis via extended X-ray absorption fine structure spectroscopy and aberration-corrected scanning transmission electron microscopy confirms the atomically dispersed Ru alloy catalyst anchored on a TiO2 support. Remarkably, Ru SAAC demonstrates exceptional electrocatalytic performance in the iodide oxidation reaction (IOR), achieving a benchmark current density of 10 mA/cm2 at a mere voltage of 0.64 V in acidic conditions within a three-electrode electrolyzer setup. Surpassing nanoscale Ru/TiO2 and RuO2/TiO2 counterparts, Ru SAAC exhibits the highest voltage efficiency (84.4%), lowest Tafel slope (36 mV/dec), and lowest overpotential (100 mV) under identical experimental conditions. This method enables facile control over Ru morphology. It enhances the kinetics and thermodynamic favorability of Ru SAAC in acidic media, opening avenues for synthesizing diverse transition metal-based single-alloy catalysts for varied applications.

A New Magnetic Coupler with High Misalignment Tolerance and Inherent Constant Current–Constant Voltage for Underground Wireless Charging

In an underground inductive power transfer (IPT), it is inevitable to produce the phenomenon of misalignment between the transmitter and the receiver, which will reduce the output current, voltage and output efficiency of the whole IPT system. Aiming to solve this problem, a universal hybrid coupler is proposed, which can still stabilize the output in the expected range and has the ability of anti-misalignment when the X and Z directions are misaligned. The coupler is composed of a BP coupler and Γ type network. The secondary edge of the coupler introduces a Γ network, which decouples the two main coils on the same side of the receiver from the auxiliary coil and reduces the complexity of the system. The coupler can effectively reduce the coupling fluctuation caused by physical movement between the downhole transmitting end and the receiving end, thereby ensuring the stable output of the coupler. As a widely used IPT system, it can access the rest of the circuit topology whose output is independent of the load and achieve misalignment-tolerant output. Finally, based on the proposed hybrid IPT coupler theory, a 500 W misalignment-tolerant coupler prototype was built, and the compensation topologies were configured as series–series (SS) and series/inductance/capacitance/capacitor (S/LCC) structures. When the X and Z direction is misaligned, the constant current and voltage independent of the load can be output by switching the compensation topology. The experimental results are the same as the theoretical analysis.

Enhancing dye-sensitized solar cells efficiency through organic dyes-sensitized holmium-doped TiO2/SnO2 nanocomposites blended with P3HT

The pursuit of sustainable energy solutions has spurred innovation in photovoltaic technology, with dye-sensitized solar cells (DSSCs) emerging as promising contenders. This study presents a novel approach leveraging holmium-doped TiO2/SnO2 nanocomposites sensitized with organic dyes, Arsenazo-III, carminic acid, and dithizone, blended with poly (3-hexylthiophene) (P3HT). Through meticulous characterization and analysis, key parameters including short-circuit current density (Jsc), open-circuit voltage (Voc), fill factor (FF), and overall percent efficiency (%) were scrutinized to evaluate photovoltaic performance comprehensively. Absorption spectra analysis facilitated the calculation of band gaps, revealing a significant reduction from 3.10 eV in pure Titania (TiO2) nanoparticles to 2.72 eV upon doping with Holmium and coupling with SnO2. Notably, Arsenazo-III dye-sensitized holmium-doped TiO2/SnO2 nanocomposites exhibited highest power conversion efficiency, achieving a promising efficiency of 2.10 %, which marked a significant improvement over the reference device (0.82 %). This improvement is attributed to the synergistic effects of holmium dopant incorporation and SnO2 interaction, enhancing light responsiveness. The findings not only validate the efficacy of nanohybrid assemblies but also contribute valuable insights to solar cell technology advancement.

Physics-Informed Machine Learning with Data-Driven Equations for Predicting Organic Solar Cell Performance.

Organic solar cells (OSCs) have emerged as a promising solution in pursuing sustainable energy. This study presents a comprehensive approach to advancing OSC development by integrating data-driven equations from quantum mechanical (QM) descriptors with physics-informed machine learning (PIML) models. We circumvent traditional experimental limitations through high-throughput QM calculations, prioritizing transparent and interpretable models. Using the SISSO++ method, we identified key descriptors that effectively map the relationships between input variables and photovoltaic performance metrics. Our innovative predictive models, derived from SISSO outputs, excel in forecasting critical OSC parameters such as short-circuit current (JSC), open-circuit voltage (VOC), fill factor (FF), and power conversion efficiency (PCEmax), achieving high accuracy even with limited data sets. To validate our models' practical utility, we applied the PIML framework to a newly compiled data set of OSC devices, demonstrating their versatility and capability in pinpointing high-performance materials. This research underscores the strong predictive power of our models, bridging the gap between experimental results and theoretical predictions and making significant contributions to the advancement of sustainable energy technologies.

Temperature dependence of water and salt transport in concentration gradient batteries: Insight from membrane properties

The performance of concentration gradient batteries (CGBs) based on reverse electrodialysis technology is inevitably influenced by seasonal temperature fluctuations; however, these effects have not been thoroughly investigated. This study explored the temperature dependence of water and salt transport in CGBs using five different membranes over a temperature range of 5–45 °C to elucidate these impacts. The results indicated that the temperature dependence of current efficiency and voltage efficiency in CGBs was respectively controlled by permeation processes (including both water and salt) and membrane resistance. The temperature dependence of mass transfer in these membranes was associated with the characteristics of the species crossing the membrane (such as size) and, more significantly, with membrane properties, including water volume fraction and fixed charge density. Therefore, we proposed that controlling these membrane characteristics can modulate the influence of temperature on mass transfer and CGB performance. This research enhanced our understanding of how temperature affects mass transfer mechanisms in different membranes and provided valuable insights for improving energy conversion in CGBs and other membrane processes.

Novel flow field design for redox flow battery using algorithmic channel generation and self-adaptive network model and experimental verification

Flow fields play a vital role in redox flow batteries (RFBs) to increase the power density. Traditional design for flow field usually employs CFD simulations with substantial computational costs and adopts enumeration and trial-and-error methods based on designers’ subjectivity, which have become a bottleneck in flow field design. In this study, a novel research paradigm is employed for flow field design in vanadium redox flow battery (VRFB), i.e., an adaptive three-dimensional equivalent network model is developed and a self-developed flow channel generation algorithm is employed to obtain optimum flow field through comparison and screening. Firstly, a flow channel library consisting of 18,135 flow fields is generated by self-developed flow channel generation algorithm. Secondly, the electrolyte flow, species transport and charge transport with various flow fields is researched by the self-adaptive equivalent network model with low computational costs due to eliminated meshing. Thirdly, pressure drop and voltage efficiency are employed to evaluate different flow fields for the aim of obtaining high-performance flow field structures through comparison and screening. The obtained high-performance flow field is fabricated and its high performance is confirmed by comprehensive experimental validation. The energy efficiency of the high-performance flow field is 4 % higher than that of the serpentine flow field investigated at 100 mA cm−2. This work employs adaptive equivalent network model to generate and optimize flow channel for the first time, which provides a reference for flow channel selection and design.

Function regionalized catalyst promoted bromine redox kinetics for bromine-based flow battery

Bromine-based flow batteries are considered as ideal large-scale energy storage devices, due to their attractive high energy density and low cost. However, the inferior redox activity of the Br3−/Br− couple leads to limited power density, which cannot meet the practical application requirements. Herein, a flexible catalytic electrode is constructed by interweaving a nitrogen-doped porous carbon (NPC) coated TiO2 (TiO2@NPC) nanofiber, via electrospinning technique. In the electrode, the NPC component with superior affinity to the reactant Br−, could assistant rapid charge transfer, and facilitate the conversion from Br− to Br3−, which plays an excellent catalytic function. With a stronger adsorption for the oxidation product Br3− than NPC, the TiO2 component can transfer Br3− from NPC, releasing the catalytic active sites on NPC timely and enabling the reaction smoothly proceeded. Consequently, the regional differentiation strategy of the catalysis and adsorption functions significantly boosts the redox kinetic of the bromine chemistry. The Zinc-bromine flow batteries equipped with TiO2@NPC can run 200 cycles stably at 80 mA cm−2, with the voltage efficiency and energy efficiency of 82.8 % and 81.6 %, respectively. This design provides a brand-new improvement strategy for bromine cathode from the perspective of accelerating the reaction rate-determining step.

Inner Side Chain Modification of Small Molecule Acceptors Enables Lower Energy Loss and High Efficiency of Organic Solar Cells Processed with Non-halogenated Solvents.

Organic solar cells (OSCs) processed with non-halogenated solvents usually suffer from excessive self-aggregation of small molecule acceptors (SMAs), severe phase separation and higher energy loss (Eloss), leading to reduced open-circuit voltage (Voc) and power conversion efficiency (PCE). Regulating the intermolecular interaction to disperse the aggregation and further improve the molecular packing order of SMAs would be an effective strategy to solve this problem. Here, we designed and synthesized two SMAs L8-PhF and L8-PhMe by introducing different substituents (fluorine for L8-PhF and methyl for L8-PhMe) on the phenyl end group of the inner side chains of L8-Ph, and investigated the effect of the substituents on the intermolecular interaction of SMAs, Eloss and performance of OSCs processed with non-halogenated solvents. Through single crystal analysis and theoretical calculations, it is found that compared with L8-PhF, which possesses strong and abundant intermolecular interactions but downgraded molecular packing order, L8-PhMe with the methyl substituent possesses more effective non-covalent interactions, which improves the tightness and order of molecular packing. When blending the SMAs with polymer donor PM6, the differences in intermolecular interactions of the SMAs influenced the film formation process and phase separation of the blend films. The L8-PhMe based blend film exhibits shorten film formation and more homogeneous phase separation than those of the L8-PhF and L8-Ph based ones. Especially, the OSCs based on L8-PhMe show reduced non-radiative energy loss and enhanced Voc than the devices based on the other two SMAs. Consequently, the L8-PhMe based device processed with o-xylene (o-XY) and using 2PACz as the hole transport layer (HTL) shows an outstanding PCE of 19.27 %. This study highlights that the Eloss of OSCs processed with non-halogenated solvents could be decreased through regulating the intermolecular interactions of SMAs by inner side chain modification, and also emphasize the importance of effectivity rather than intensity of non-covalent interactions introduced in SMAs on the molecular packing, morphology and PCE of OSCs.

Application of AgInSe2 nanoparticles to boost the power conversion efficiency of CdS QDs-sensitized solar cells

In this study, bandgap engineering was utilized to assess the efficiency of photoanodes incorporating CdS nanocrystals and AgInSe2 (AISe) quantum dots (QDs) in quantum dot-sensitized solar cells (QDSSCs). Initially, the deposition of CdS(Xc) nanocrystal layers on a TiO2 substrate was tested using the SILAR method with varying cycles (X = 1–6). Optical transmission analysis revealed a redshift in the absorption edge and reduced transmission with an increasing number of cycles. J-V analysis of TiO2 NCs/CdS(Xc) photoanodes identified cycle X = 5 as optimal. The short-circuit current density (Jsc), open-circuit voltage (Voc), fill factor (FF) and maximum power conversion efficiency (PCE) were 15.5 mA/cm2, 614 mV, 40 %, and 3.76 %, respectively. Subsequently, pre-synthesized AISe QDs were deposited on TiO2 nanocrystals/CdS(Xc) photoanodes, exhibiting a single absorption edge with a bandgap energy of 2.19 eV for all photoanodes. The TiO2 NCs/CdS(5c)/AISe/ZnS photoanode showed an increase in Jsc and efficiency, reaching 17.25 mA/cm2 and 4.27 %, respectively. Utilizing sub-micron-sized TiO2 hollow spheres (HSs) as a light-scattering layer further enhanced light absorption and performance. It was demonstrated that this approach increased the photovoltaic parameters to a Jsc of 19.12 mA/cm2, FF of 43 %, and an overall efficiency of 4.75 %.