Power Conversion Research Articles

Non-fused Nonfullerene Acceptors with an Asymmetric Benzo[1,2-b:3,4-b', 6,5-b"]trithiophene (BTT) Donor Core and Different AcceptorTerminal Units for Organic Solar Cells.

Here in, we have designed two new unfused non-fullerene small molecules using asymmetric benzo[1,2-b:3.4-b', 6,5-b"]trithiophene (BTT) as the central donor core and different terminal units i. e., 2-(3-oxo-2,3-dihydro-1H-inden-1-ylidene)malononitrile (NFA-4) and 1,3-diethyl-2-thioxodi hydropyrimidine-4,6 (1H,5H)-dione (NFA-5) and examined their optical and electrochemical properties. Using a wide band-gap copolymer D18, organic solar cells (OSCs) based on bulk heterojunction of D18:NFA-4 and D18:NFA-5 showed overall power conversion efficiency (PCE) of about 17.07 % and 11.27 %, respectively. The increased PCE for the NFA-4-based OSC, compared to NFA-5 counterpart, is due higher value of short circuit current (JSC), open circuit voltage (VOC), and fill factor (FF). Following the addition of small amount of NFA-5 to the binary bulk heterojunction D18:NFA-4, the ternary organic solar cells attained a PCE of 18.05 %, surpassing that of the binary counterparts due to the higher values of which is higher than that for the binary counterparts and attributed to the increased values of JSC, FF, and VOC. The higher value of JSC is linked to the efficient use to excitons transferred from NFA-5 to NFA-4 with a greated dipole moment than NFA-5 and subsequently dissociated into a free charge carrier efficiently.

TVT‐Based New Building Block with Enhanced π‐Electron Delocalization for Efficient Non‐Fused Photovoltaic Acceptor

AbstractTo address the high‐cost issue that impedes the large‐scale fabrication and industrialization of organic solar cells (OSCs), it is crucial to design low‐cost photovoltaic materials with simplified synthesis procedures. In this study, a novel fully non‐fused acceptor, ATVT‐BO, featuring a triisopropylbenzene‐substituted (E)‐1,2‐di(thiophen‐2‐yl)ethene (TVT) unit as the central core is designed and synthesized. A control acceptor, A4T‐BO, with the same alkyl chains but a bithiophene central core, is also synthesized for comparison. Theoretical calculations and practical measurements reveal that compared to A4T‐BO, the insertion of an ethylene bond in ATVT‐BO enhances the molecular planarity and reduces the aromaticity, leading to enhanced π‐electron delocalization and thus improved electron mobility and a red‐shifted optical absorption spectrum. The 3D molecular packing mode of ATVT‐BO, characterized by tight intermolecular interactions, also promotes efficient charge transport in OSCs. Consequently, when paired with the low‐cost polymer PTVT‐T, featuring an ester‐substituted TVT structure, as the photoactive layer, the PTVT‐T:ATVT‐BO‐based device achieves a remarkable power conversion efficiency of 14.8%, distinctly higher than that of PTVT‐T:A4T‐BO‐based cell. The result highlights the significant potential of TVT units in creating both low‐cost polymer donors and fully non‐fused acceptors, which opens up new possibilities for designing low‐cost photoactive materials in OSCs.

A Scorpion–Type Dopant‐Free Hole Transport Material for n‐i‐p Organic–Inorganic Hybrid Perovskite Solar Cells

AbstractIt is significant to develop dopant‐free hole transport materials (HTMs) to improve the long‐term stability of n‐i‐p organic–inorganic hybrid perovskite solar cells (PSCs). In this work, two HTMs (DTTP‐T and DTTP‐D) based on dithienothiopyrrole (DTTP) core were synthesized to explore the effects of different substituents on the nitrogen atom on the properties of HTMs. Compared with anisole‐substituted DTTP‐D, triarylamine‐substituted scorpion‐type DTTP‐T shows better matching energy level, stronger charge transfer and defect passivation ability. Therefore, the power conversion efficiency (PCE) of dopant‐free DTTP‐T‐based n‐i‐p PSCs reaches 18.67 %, which is comparable to that of doped Spiro‐OMeTAD (19.51 %). More encouragingly, the efficiency of DTTP‐T‐based devices remains above 80 % of its initial efficiency after 1728 h of storage in air, while the Spiro‐OMeTAD‐based devices could only maintain 600 h. This work provides a good reference for the development of dopant‐free small molecular HTMs for efficient and stable PSCs.

Direct Laser Interference Patterning of Fluorine‐Doped Tin Oxide as a Pathway to Higher Efficiency in Perovskite Solar Cells

AbstractImproving light‐trapping capabilities through surface microstructuring of transparent conductive oxides is a promising approach to enhance solar cell efficiency. This study focuses on treating fluorine‐doped tin oxide (FTO) thin films using four‐beam direct laser interference patterning (DLIP) to create dot‐like periodic surface microstructures. The surface analysis using scanning electron microscopy and confocal microscopy reveals the presence of a periodic square grid of microcraters with a spatial period of ≈700 nm and an average depth ranging between 4 and 18 nm. These structures enhance the dispersion of incoming light up to 1000% in the visible and NIR spectra. When integrated into metal halide perovskite solar cells, FTO films patterned using low fluence conditions lead to a notable increase in the power conversion efficiencies (PCEs) compared to those made using untreated FTO. Importantly, preliminary stability tests on devices based on patterned FTO substrates show significantly improved stability compared to those fabricated using reference unpatterned substrates. These findings demonstrate that a DLIP treatment of FTO substrates is a promising technique that can substantially enhance the efficiency and stability of perovskite photovoltaic devices.

Nanotech‐Enhanced Chemical Energy Storage with DNA

AbstractDNA nanotechnology has revolutionized materials science by harnessing DNA's programmable properties. DNA serves as a versatile biotemplate, facilitating the creation of novel materials such as electrode materials and DNA hydrogels for electrolytes and membranes. These advancements have significantly boosted the performance of energy storage devices. DNA biotemplates not only enhance supercapacitor capacitance and increase Li–S battery cycling stability but also improve metal ion transport in perovskite solar cells, enhancing power conversion efficiency. Additionally, DNA's addressable nature allows precise enzyme positioning in biofuel cells, enhancing enzyme cascade efficiency. Overall, DNA nanotechnology offers a potent strategy for enhancing electrochemical device performance and stability through structural engineering.

Magnetically Integrated Multiport Converter for Energy Management in DC-Powered Buildings

Multiport converters have gained attention in the last few years as a key component for dc-powered buildings, more electric aircraft, and maritime applications. For buildings, the prevalence of dc appliances and electronic loads increases the need for efficient integration with both ac grid and local generation. Ac-dc multiport converters play an important role in this integration because dc distribution has been considered for power integration in modern buildings. In addition, the growing complexity of loads and sources within buildings has driven interest in developing flexible solutions to provide highly efficient integration. Furthermore, ongoing developments in standardization for in-building dc grids underscore the importance of considering specific requirements for future designs. This paper proposes a multiport power converter (ac/dc/dc) to integrate dc-powered buildings into an ac grid. By providing a multiport solution, it is possible to reduce the power processing stages and the component count. To evaluate the effectiveness of this concept, a 5-kW prototype was built and tested, including efficiency evaluation. In addition, emerging standards are discussed to tailor the power converter design for building applications.

Talk2Care: Facilitating Asynchronous Patient-Provider Communication with Large-Language-Model

Despite the plethora of telehealth applications to assist home-based older adults and healthcare providers, basic messaging and phone calls are still the most common communication methods, which suffer from limited availability, information loss, and process inefficiencies. One promising solution to facilitate patient-provider communication is to leverage large language models (LLMs) with their powerful natural conversation and summarization capability. However, there is a limited understanding of LLMs' role during the communication. We first conducted two interview studies with both older adults (N=10) and healthcare providers (N=9) to understand their needs and opportunities for LLMs in patient-provider asynchronous communication. Based on the insights, we built an LLM-powered communication system, Talk2Care, and designed interactive components for both groups: (1) For older adults, we leveraged the convenience and accessibility of voice assistants (VAs) and built an LLM-powered conversational interface for effective information collection. (2) For health providers, we built an LLM-based dashboard to summarize and present important health information based on older adults' conversations with the VA. We further conducted two user studies with older adults and providers to evaluate the usability of the system. The results showed that Talk2Care could facilitate the communication process, enrich the health information collected from older adults, and considerably save providers' efforts and time. We envision our work as an initial exploration of LLMs' capability in the intersection of healthcare and interpersonal communication.

Enhancing the Efficiency and Stability of Inverted Perovskite Solar Cells and Modules through Top Interface Modification with N‐type Semiconductors

The interface modification between perovskite and electron transport layer (ETL) plays a crucial role in achieving high performance inverted perovskite photovoltaics (i‐PPVs). Herein, non‐fullerene acceptors (NFAs), known as Y6‐BO and Y7‐BO, were utilized to modify the perovskite/ETL interface in i‐PPVs. Non‐polar solvent‐soluble NFAs can effectively passivate surface defects without structural damage of the underlying perovskite films. Additionally, the improved PCBM ETL induced by NFAs modification significantly accelerates the electrons extraction. As a result, both Y6‐BO and Y7‐BO exhibit more effective interface modification effects compared to traditional PI molecules. The power conversion efficiency (PCE) of the inverted perovskite solar cell (i‐PSC) modified with Y7‐BO reaches 25.82%. Moreover, the adoption of non‐polar solvents and the superior semiconductor properties of Y7‐BO molecules also enable perovskite solar modules (i‐PSM) with effective areas of 50 cm2, 400 cm2, and 1160 cm2 to achieve record efficiencies of 23.05%, 22.32%, and 21.1% (certified PCE), respectively, making them the best PCE reported in the literature. Importantly, enhanced interface mechanical strength between the perovskite and PCBM layer results in significantly improved environmental and operational stability of the cells. The cells modified with Y7‐BO maintained 94.4% of the initial efficiency after 1522 hours of maximum power point aging.

Enhancing the Efficiency and Stability of Inverted Perovskite Solar Cells and Modules through Top Interface Modification with N‐type Semiconductors

The interface modification between perovskite and electron transport layer (ETL) plays a crucial role in achieving high performance inverted perovskite photovoltaics (i‐PPVs). Herein, non‐fullerene acceptors (NFAs), known as Y6‐BO and Y7‐BO, were utilized to modify the perovskite/ETL interface in i‐PPVs. Non‐polar solvent‐soluble NFAs can effectively passivate surface defects without structural damage of the underlying perovskite films. Additionally, the improved PCBM ETL induced by NFAs modification significantly accelerates the electrons extraction. As a result, both Y6‐BO and Y7‐BO exhibit more effective interface modification effects compared to traditional PI molecules. The power conversion efficiency (PCE) of the inverted perovskite solar cell (i‐PSC) modified with Y7‐BO reaches 25.82%. Moreover, the adoption of non‐polar solvents and the superior semiconductor properties of Y7‐BO molecules also enable perovskite solar modules (i‐PSM) with effective areas of 50 cm2, 400 cm2, and 1160 cm2 to achieve record efficiencies of 23.05%, 22.32%, and 21.1% (certified PCE), respectively, making them the best PCE reported in the literature. Importantly, enhanced interface mechanical strength between the perovskite and PCBM layer results in significantly improved environmental and operational stability of the cells. The cells modified with Y7‐BO maintained 94.4% of the initial efficiency after 1522 hours of maximum power point aging.

Design of a triple port integrated topology for grid-integrated EV charging stations for three-way power flow

Environmental fluctuations, solar irradiance, and ambient temperature significantly affect photovoltaic (PV) system output. PV systems should be efficient at the Maximum Power Point in various weather climates to maximize their potential power output. The Maximum Power Point Tracking (MPPT) technique is employed to plan a specific location that yields the maximum amount of power. Operating dispersed alternative energy sources connected to the grid in this situation makes energy control an unavoidable task. This research article suggests designing a power electronics converter topology that links sustainable resources and electric vehicles to the power grid. There are four modes of operation for this proposed converter topology: grid-to-vehicle, vehicle-to-grid, renewable-to-vehicle, and renewable-to-grid discussed. The three power electronic converters and their uses are discussed, and their controllers are also designed to maintain the energy balance and stability in all cases. The battery characteristics indicate the operating mode. The work primarily focuses on the converter’s Triple Port Integrated Topology (TPIT) power flow and voltage control. Here, three power converters integrate the TPIT with three systems-the electric grid, renewable energy, and electric vehicles-into one system. The source battery and solar photovoltaic (PV) array cells are integrated using unidirectional and bidirectional DC-DC converters. The future scope of the work is to investigate the potential of adding additional ports for integrating other energy resources, such as hydrogen fuel cells or additional renewable sources, to create a more versatile and robust energy management system for EV charging stations.

Charge Dynamics and Defect States under “Spot‐Light”: Spectroscopic Insights into Halide Perovskite Solar Cells

Halide perovskite solar cells (PSCs) have shown remarkable power conversion efficiencies. However, the inherent defect issues of perovskite materials still limit their performance and long‐term stability, resulting in lifespans far from commercial standards. With their noninvasive approach to probing the electronic and vibrational properties of materials, spectroscopic techniques have become crucial tools for uncovering and understanding defect states and complex charge carrier dynamics in halide perovskites. This review explores the application of various advanced spectroscopic techniques in PSCs to elucidate the complex behaviors of charge carriers within PSCs. These techniques reveal detailed temporal and spatial distributions of charge carriers, enabling precise analysis of defect impacts and interfacial charge transfer processes. By integrating spectroscopic data, it is possible to more accurately identify and mitigate defect‐induced nonradiative recombination and charge transfer, thereby enhancing the stability and efficiency of PSCs. This comprehensive spectroscopic understanding is crucial for developing innovative technologies to accelerate the commercial viability of PSCs.

A Mixed‐Pure Planar Heterojunction Structure of Active Layers for Efficient Sequential Blade‐Coating Organic Solar Cells

AbstractPrecise modulating the vertical structure of active layers to boost charge transfer is an effective way to achieve high power conversion efficiencies (PCEs) in organic solar cells (OSCs). Herein, efficient OSCs with a well‐controlled vertical structure are realized by a rapid film‐forming method combining low boiling point solvent and the sequential blade‐coating (SBC) technology. The results of grazing incident wide‐angle X‐ray scattering measurement show that the vertical component distribution is varied by changing the processing solvent. Novel characterization technique such as tilt resonant soft X‐ray scattering is used to test the vertical structure of the films, demonstrating the dichloromethane (DCM)‐processed film is truly planar heterojunction. The devices with chloroform (CF) processed upper layer show an increased mixed phase region compared to these devices with toluene (TL) or ‐DCM‐, which is beneficial for improving charge generation and achieving a superior PCE of 17.36%. Despite significant morphological varies, the DCM‐processed devices perform slightly lower PCE of 16.66%, which is the highest value in truly planar heterojunction devices, demonstrating higher morphological tolerance. This work proposes a solvent‐regulating method to optimize the vertical structure of active layers through SBC technology, and provides a practical guidance for the optimization of the active‐layer microstructure.

LCL APF control strategy based on model predictive control

In order to further control harmonic current in distribution network, a LCL APF control strategy based on model predictive control is proposed. Firstly, APF mathematical model is established. Then, a multi-objective optimization model predictive control strategy (MPC) is proposed, which comprehensively considers the performance of AC side and DC side of APF. This strategy solves the delay problem existing in the existing MPC strategy: while improving the performance of APF, there is no need to set weight factor; Then, Kalman filter is used to predict the inverter current, thus simplifying the APF measurement system. Finally, the simulation results show that the proposed control strategy can simplify the measurement system and make APF have stronger harmonic suppression ability when it only participates in power conversion and better active filter performance when it participates in harmonic control.

Layer-by-Layer Deposition of Hollow TiO2 Spheres with Enhanced Photoelectric Conversion Efficiency for Dye-Sensitized Solar Cell Applications

Fabricating photoanodes with a strong light-scattering effect can improve the photoconversion efficiency of dye-sensitized solar cells (DSSCs). In this work, a facile microwave hydrothermal process was developed to prepare Au@TiO2 core–shell nanostructures, and then the Au core was removed by etching, resulting in hollow TiO2. Morphological characterizations such as field emission scanning and transmission electron microscopy measurements have been used for the successful formation of core–shell and hollow TiO2 nanostructures. Next, we attempted to deposit the different-sized hollow TiO2-based microspheres simultaneously on the surface of small-sized TiO2 nanoparticles-based compact film as light-scattering layers via electrophoretic deposition. The deposited hollow TiO2 microspheres constitute bi- and tri-layers that not only improve the light-harvesting properties but also speed up the photogenerated charge transfer. Compared to commercial TiO2 compact film (4.75%), the resulting bi-layer and tri-layered films-based DSSCs displayed power conversion efficiencies of 6.33% and 8.08%, respectively. It is revealed that the deposited bi- and tri-layered films can enhance the light absorption ability via multiple photon reflection. This work validates a novel and controllable strategy to develop light-scattering layers with increased light-harvesting properties for highly efficient dye-sensitized solar cells.

Standing 1D Chains Enable Efficient Wide-Bandgap Selenium Solar Cells.

The recent surge in tandem solar cells and indoor photovoltaics has renewed interest in selenium (Se), the world's first photovoltaic material, due to its intrinsic wide bandgap of ≈1.9eV, high stability, and non-toxicity in small quantities when applied in photovoltaics. However, with a 1D chained crystal structure, Se tends to grow crystalline films with a lying orientation-chains parallel to substrates arising from the low surface energy; this results in poor carrier transport across chains held together by weak van der Waals forces. Here a substrate-heating strategy that facilitates the interfacial bonding between Se and substrate is introduced, enabling the growth of Se films with a standing orientation-chains perpendicular to substrates. This achieves efficient carrier transport along covalently bonded chains. The resulting Se films thereby exhibit a fourfold increase in carrier mobility compared to lying-oriented Se films. Consequently, Se solar cells are achieved with the highest power conversion efficiency of 8.1% under AM1.5G 1-sun illumination. The unencapsulated devices exhibit negligible efficiency loss after 1000 h of storage under ambient conditions.

Innovations and Challenges in Semi-Transparent Perovskite Solar Cells: A Mini Review of Advancements Toward Sustainable Energy Solutions

Amid the shift away from fossil fuels, third-generation perovskite solar cells (PSCs) have become pivotal due to their high efficiency and low production costs. This review concentrates on semi-transparent perovskite solar cells (ST-PSCs), highlighting their power conversion efficiency (PCE) and average visible transmittance (AVT). We address strategies to optimize ST-PSC performance, tackling inherent challenges, such as optical losses from reflection, parasitic absorption, and thermalization loss, which impact the operational efficiency under variable environmental conditions. ST-PSCs are distinguished by their lightweight, flexible, and translucent properties, allowing for diverse applications in urban building integration, agricultural greenhouses, and wearable technology. These cells integrate seamlessly into various settings, enhancing energy harnessing without compromising on aesthetic or structural elements. However, the scalability of ST-PSCs involves challenges related to stability and efficiency in large-scale deployments. The tropical urban landscape of Singapore provides a unique case study for ST-PSC application, blending architectural aesthetics with high solar irradiance to optimize energy efficiency. While the potential for ST-PSCs to contribute to sustainable urban development is immense, significant technological hurdles must be overcome to realize their full potential. Continued advancements in material science and engineering are essential to address these challenges, ensuring the scalability and long-term deployment of ST-PSCs in global energy solutions.

Impact of Tetrakis(dimethylamido)tin(IV) Degradation on Atomic Layer Deposition of Tin Oxide Films and Perovskite Solar Cells.

Tin oxide (SnOx) films synthesized by atomic layer deposition (ALD) are widely explored in a range of optoelectronic devices including electrochemical sensors, transistors, and photovoltaics. However, the integrity of the key ALD-SnOx precursor, namely tetrakis(dimethylamido)tin (IV) (TDMASn), and its influence on the properties of ultimate films remain unexplored. Here a significant degradation of TDMASn into bis(dimethylamido)tin(II) via the Sn-imine complex is reported, and its impact on the corresponding films and devices is examined. It is found, surprisingly, that this degradation does not affect the growth kinetics and morphology of ALD-SnOx films. But it notably deteriorates their electronic properties, resulting in films with twice the electrical resistance due to different oxidation mechanisms of the degradation products. Perovskite solar cells employing such films exhibit a significant loss in power conversion efficiency, primarily due to charge transport and transfer losses. These findings urge strategies to stabilize TDMASn, a critical precursor for ALD-SnOx films, or to identify alternative materials to achieve efficient and reliable devices.

Stereo-Hindrance Induced Conformal Self-Assembled Monolayer for High Efficiency Inverted Perovskite Solar Cells.

Self-assembled monolayers (SAMs) are employed as hole-selective contacts in inverted perovskite solar cells (PSCs) and have achieved record power conversion efficiency (PCE) over 26%. However, the tendency of extensively employed SAM [2-(3,6-Dimethoxy-9H-carbazol-9-yl)ethyl]phosphonic acid to aggregate leads to its uneven coverage to the transparent conducting oxide substrate, which subsequently compromises the photovoltaic performance. Herein, a novel tert-butyl functionalized phosphonic acid carbazole SAM is developed, i.e., (4-(3,6-di-tert-butyl-9H-carbazol-9-yl)butyl)phosphonic acid (tBu-4PACz), and introduced to a mixed SAM system as the hole-extraction layer in inverted PSCs. The stereo-hindrance of the bulky tert-butyl group prevents undesired aggregation and leads to better conformality, which facilitates more efficient hole-extraction and suppresses interfacial recombination losses. The tBu-4PACz SAM-based inverted PSC has achieved record level PCE of 26.25% (26.21%, certificated) with outstanding fill factors over 86%. Moreover, the mixed SAM based inverted PSC devices maintained over 94.7% of their initial efficiency after 500h continuous maximum power-point tracking under simulation 1-sun irradiation.

Ethanol Processable Inorganic‐Organic Hybrid Hole Transporting Layers Enabled 20.12 % Efficiency Organic Solar Cells

AbstractIn this study, a high‐performance inorganic‐organic hybrid hole transporting layer (HTL) was developed using ethanol‐soluble alkoxide precursors and a self‐assembled monolayer (SAM). Three metal oxides‐vanadium oxide (VOx), niobium oxide (Nb2O5), and tantalum oxide (Ta2O5)‐were synthesized through successive low‐temperature (100 °C) thermal annealing (TA) and UV‐ozone (UVO) treatments of their respective precursors: vanadium oxytriethoxide (EtO−V), niobium ethoxide (EtO−Nb), and tantalum ethoxide (EtO−Ta). Among these, the Nb2O5 film exhibited excellent transmittance, a high work function, and good conductivity, along with a more compact and uniform structure featuring fewer interfacial defects, which facilitated efficient charge extraction and transport. Furthermore, the deposition of a SAM of (2‐(9H‐carbazol‐9‐yl)ethyl)phosphonic acid (2PACz) on top of Nb2O5 further passivated defects, enhancing interfacial contact with the photoactive layer. The resulting inorganic‐organic hybrid HTL of Nb2O5/2PACz demonstrated excellent compatibility with various photoactive blends, achieving impressive power conversion efficiencies of 19.44 %, 19.18 %, and 20.12 % for the PM6:L8‐BO, PM6:BTP‐eC9, and D18:BTP‐eC9 based organic solar cells, respectively. 20.12 % is the best performance for bulk heterojunction organic solar cells with binary components as the photoactive layer.

Chalcogenides in Perovskite Solar Cells with a Carbon Electrode: State of the Art and Future Prospects

Perovskite solar cells (PSCs) have been on the forefront of advanced research for over a decade, achieving constantly increasing power conversion efficiencies (PCEs), while their route towards commercialization is currently under intensive progress. Towards this target, there has been a turn to PSCs that employ a carbon electrode (C-PSCs) for the elimination of metal back contacts, which increase the cost of corresponding devices while at the same time have a severe impact on their stability. Chalcogenides are chemical compounds that contain at least one chalcogen element, typically sulfur (S), selenium (Se), or tellurium (Te), combined with one metallic element. They possess semiconducting properties and have been proven to have beneficial effects when incorporated in a variety of solar cell types, including dye sensitized solar cells (DSSCs), quantum dot sensitized solar cells (QDSSCs), and Organic Solar Cells (OSCs), either as interlayers or added in the active layers. Currently, an increasing number of studies have highlighted their potential for achieving high-performing and stable PSCs. In this review, the most promising results of the latest studies regarding the implementation of chalcogenides in PSCs with a carbon electrode are presented and discussed, merging two research trends that are currently on the spotlight of solar cell technology.