Recent Submissions

  • Mechanical Reliability of Fullerene/Tin Oxide Interfaces in Monolithic Perovskite/Silicon Tandem Cells

    de Bastiani, Michele; Armaroli, Giovanni; Jalmood, Rawan S.; Ferlauto, Laura; Li, Xiaole; Tao, Ran; Harrison, George T.; Eswaran, Mathan Kumar; Azmi, Randi; Babics, Maxime; Subbiah, Anand Selvin; Aydin, Erkan; Allen, Thomas; Combe, Craig; Cramer, Tobias; Baran, Derya; Schwingenschlögl, Udo; Lubineau, Gilles; Cavalcoli, Daniela; De Wolf, Stefaan (ACS Energy Letters, American Chemical Society (ACS), 2022-01-25) [Article]
    High-efficiency perovskite-based solar cells comprise sophisticated stacks of materials which, however, often feature different thermal expansion coefficients and are only weakly bonded at their interfaces. This may raise concerns over delamination in such devices, jeopardizing their long-term stability and commercial viability. Here, we investigate the root causes of catastrophic top-contact delamination we observed in state-of-the-art p-i-n perovskite/silicon tandem solar cells. By combining macroscopic and microscopic analyses, we identify the interface between the fullerene electron transport layer and the tin oxide buffer layer at the origin of such delamination. Specifically, we find that the perovskite morphology and its roughness play a significant role in the microscopic adhesion of the top layers, as well as the film processing conditions, particularly the deposition temperature and the sputtering power. Our findings mandate the search for new interfacial linking strategies to enable mechanically strong perovskite-based solar cells, as required for commercialization.
  • MXene-Coated Membranes for Autonomous Solar-Driven Desalination

    Mustakeem, Mustakeem; El Demellawi, Jehad K.; Obaid, M.; Ming, Fangwang; Alshareef, Husam N.; Ghaffour, NorEddine (ACS Applied Materials & Interfaces, American Chemical Society (ACS), 2022-01-21) [Article]
    Clean water supply in off-grid locations remains a stumbling stone for socio-economic development in remote areas where solar energy is abundant. In this regard, several technologies have already introduced various solutions to the off-grid freshwater predicament; however, most of them are either costly or complex to operate. Nonetheless, photothermal membrane distillation (PMD) has emerged as a promising candidate with great potential to be autonomously driven by solar energy. Instead of using energy-intensive bulk feed heating in conventional MD systems, PMD membranes can directly harvest the incident solar light at the membrane interface as an alternative driving energy resource for the desalination process. Because of its excellent photothermal properties and stability in ionic environments, herein, Ti3C2Tx MXene was coated onto commercial polytetrafluoroethylene (PTFE) membranes to allow for a self-heated PMD process. An average water vapor flux of 0.77 kg/m2 h with an excellent temporal response under intermitting lighting and a photothermal efficiency of 65.3% were achieved by the PMD membrane under one-sun irradiation for a feed salinity of 0.36 g/L. Naturally, the efficiency of the process decreased with higher feed concentrations due to the reduction of the evaporation rate and the scattering of incident sunlight toward the membrane photothermal surface, especially at rates above 10 g/L. Notably, with such performance, 1 m2 of the MXene-coated PMD membrane can fulfill the recommended daily potable water intake for a household, that is, ca. 6 L/day.
  • MXenes for Energy Harvesting

    Wang, Yizhou; Guo, Tianchao; Tian, Zhengnan; Bibi, Khadija; Zhang, Yi-Zhou; Alshareef, Husam N. (Advanced Materials, Wiley, 2022-01-20) [Article]
    Energy-harvesting modules play an increasingly important role in the development of autonomous self-powered microelectronic devices. MXenes (i.e., two-dimensional transition metal carbide/nitride) have recently emerged as promising candidates for energy applications due to their excellent electronic conductivity, large specific surface area, and tunable properties. In this review, we present a perspective on using MXenes to harvest energy from various sources in the environment. First, we systematically introduce the characteristics of MXenes that facilitate energy capturing and summarize the preparation strategies of MXenes and their derived nanostructures tailored towards such applications. Subsequently, we discuss the harvesting mechanism of different energy sources (e.g., solar energy, thermoelectric energy, triboelectric energy, piezoelectric energy, salinity gradient energy, electrokinetic energy, ultrasound energy, and humidity energy). Then we introduce the recent progress of MXene-based nanostructures in energy harvesting, as well as their applications. Finally, we present our opinions on the existing challenges and future directions of MXene-based nanostructure for energy harvesting.
  • Wafer-scale single-crystal monolayer graphene grown on sapphire substrate

    Li, Junzhu; Chen, Mingguang; Samad, Abdus; Dong, Haocong; Ray, Avijeet; Zhang, Junwei; Jiang, Xiaochuan; Schwingenschlögl, Udo; Domke, Jari; Chen, Cailing; Han, Yu; Fritz, Torsten; Ruoff, Rodney S.; Tian, Bo; Zhang, Xixiang (Nature Materials, Springer Science and Business Media LLC, 2022-01-20) [Article]
    The growth of inch-scale high-quality graphene on insulating substrates is desirable for electronic and optoelectronic applications, but remains challenging due to the lack of metal catalysis. Here we demonstrate the wafer-scale synthesis of adlayer-free ultra-flat single-crystal monolayer graphene on sapphire substrates. We converted polycrystalline Cu foil placed on Al2O3(0001) into single-crystal Cu(111) film via annealing, and then achieved epitaxial growth of graphene at the interface between Cu(111) and Al2O3(0001) by multi-cycle plasma etching-assisted–chemical vapour deposition. Immersion in liquid nitrogen followed by rapid heating causes the Cu(111) film to bulge and peel off easily, while the graphene film remains on the sapphire substrate without degradation. Field-effect transistors fabricated on as-grown graphene exhibited good electronic transport properties with high carrier mobilities. This work breaks a bottleneck of synthesizing wafer-scale single-crystal monolayer graphene on insulating substrates and could contribute to next-generation graphene-based nanodevices.
  • Interfaces between Pb-Free Double Perovskite Cs2NaBiI6 and MXenes Sc2CO2 and Sc2C(OH)2

    Albar, Arwa; Schwingenschlögl, Udo (The Journal of Physical Chemistry Letters, American Chemical Society (ACS), 2022-01-19) [Article]
    First-principles calculations are used to explore the electronic properties of the interfaces between the Pb-free double perovskite Cs2NaBiI6 and the MXenes Sc2CO2 and Sc2C(OH)2. The effect of the termination group on the stability, ionization potential, electron affinity, and band alignment is investigated. We find a type II band alignment at the Cs2NaBiI6/Sc2CO2 interface, which permits charge transfer, and a type III band alignment at the Cs2NaBiI6/Sc2C(OH)2 interface, which results in electron–hole recombination. Sc2CO2 turns out to be highly promising for solar cell applications due to an almost ideal ionization potential difference to Cs2NaBiI6.
  • Effects of Vertical Molecular Stratifications and Microstructures on the Properties of Fullerene-Free Organic Solar Cells

    Peña, Top Archie Dela; Ma, Ruijie; Sharma, Anirudh; Xing, Zengshan; Jin, Zijing; Wang, Jiannong; Baran, Derya; Weng, Lu-Tao; Yan, He; Wong, Kam Sing (Advanced Photonics Research, Wiley, 2022-01-18) [Article]
    From the past years, the most commonly reported state-of-the-art binary bulk heterojunction organic solar cells (OSCs) are mostly based on mixtures of polymer donors and fullerene-free acceptors (polymer:NFA). However, along with it are a number of contradictory propositions, including (but not limited to) strategies to reduce energy loss and improve photocurrent generation through energy level alignments. Due to the resulting high similarity of molecular fragments from polymer:NFA heterojunctions, the effects of vertical molecular stratification are not yet well studied. Herein, the time-of-flight secondary ion mass spectrometry (ToF-SIMS) molecular depth profiling reveals a vertical stratification in PM6:IT-4Cl and illustrates how it can significantly influence the photovoltaic properties. The said inhomogeneity is also bound to introduce microstructure variations within device active layers. Consequently, it is systematically demonstrated how thin-film microstructures can influence optoelectronic properties, wherein important metrics (e.g., energy losses and molecular energy offsets) are highly dependent. Thus, the understanding from this work provides foundations for more precise development of strategies to further advance OSC technology in future studies.
  • Self-Assembly and Regrowth of Metal Halide Perovskite Nanocrystals for Optoelectronic Applications

    Liu, Jiakai; Zheng, Xiaopeng; Mohammed, Omar F.; Bakr, Osman (Accounts of Chemical Research, American Chemical Society (ACS), 2022-01-16) [Article]
    Conspectus Over the past decade, the impressive development of metal halide perovskites (MHPs) has made them leading candidates for applications in photovoltaics (PVs), X-ray scintillators, and light-emitting diodes (LEDs). Constructing MHP nanocrystals (NCs) with promising optoelectronic properties using a low-cost approach is critical to realizing their commercial potential. Self-assembly and regrowth techniques provide a simple and powerful “bottom-up” platform for controlling the structure, shape, and dimensionality of MHP NCs. The soft ionic nature of MHP NCs, in conjunction with their low formation energy, rapid anion exchange, and ease of ion migration, enables the rearrangement of their overall appearance via self-assembly or regrowth. Because of their low formation energy and highly dynamic surface ligands, MHP NCs have a higher propensity to regrow than conventional hard-lattice NCs. Moreover, their self-assembly and regrowth can be achieved simultaneously. The self-assembly of NCs into close-packed, long-range-ordered mesostructures provides a platform for modulating their electronic properties (e.g., conductivity and carrier mobility). Moreover, assembled MHP NCs exhibit collective properties (e.g., superfluorescence, renormalized emission, longer phase coherence times, and long exciton diffusion lengths) that can translate into dramatic improvements in device performance. Further regrowth into fused MHP nanostructures with the removal of ligand barriers between NCs could facilitate charge carrier transport, eliminate surface point defects, and enhance stability against moisture, light, and electron-beam irradiation. However, the synthesis strategies, diversity and complexity of structures, and optoelectronic applications that emanate from the self-assembly and regrowth of MHPs have not yet received much attention. Consequently, a comprehensive understanding of the design principles of self-assembled and fused MHP nanostructures will fuel further advances in their optoelectronic applications. In this Account, we review the latest developments in the self-assembly and regrowth of MHP NCs. We begin with a survey of the mechanisms, driving forces, and techniques for controlling MHP NC self-assembly. We then explore the phase transition of fused MHP nanostructures at the atomic level, delving into the mechanisms of facet-directed connections and the kinetics of their shape-modulation behavior, which have been elucidated with the aid of high-resolution transmission electron microscopy (HRTEM) and first-principles density functional theory calculations of surface energies. We further outline the applications of assembled and fused nanostructures. Finally, we conclude with a perspective on current challenges and future directions in the field of MHP.
  • Air-Processable and Thermally Stable Hole Transport Layer for Non-Fullerene Organic Solar Cells

    Bertrandie, Jules; Sharma, Anirudh; Gasparini, Nicola; Rosas Villalva, Diego; Paleti, Sri Harish Kumar; Wehbe, Nimer; Troughton, Joel; Baran, Derya (ACS Applied Energy Materials, American Chemical Society (ACS), 2022-01-10) [Article]
    Power conversion efficiencies (PCEs) of organic solar cells (OSCs) have now surpassed 19%. This has led to an increased focus on developing devices using methods and materials that are scalable, processable under ambient air atmospheres, and stable. However, current materials fall short of the essential requirements for stability and processability needed for cost-effective large-scale fabrication of high-performing OSCs. Here, we report a hybrid solution-processable hole transport layer (HTL) based on tantalum-doped tungsten oxide (TaWOx) nanoparticles and poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) demonstrating good wettability over the hydrophobic active layer. N-i-p-type OSCs that are processed fully under ambient conditions, based on a polymer donor and a non-fullerene acceptor incorporating a combined TaWOx-PEDOT:PSS layer as HTL deliver a power conversion efficiency of 8.6%. OSCs utilizing the TaWOx-PEDOT:PSS HTL demonstrate improved thermal stability compared to devices based on the previously reported solution-processed MoOx-PEDOT:PSS HTL, which was found to severely degrade upon thermal treatment at 85 °C. Photoelectron spectroscopy and secondary ion mass spectrometry (SIMS) reveal that the MoOx-PEDOT:PSS HTL is prone to thermally induced intermixing with the underlying active layer, resulting in unfavorable changes in the interfacial energetics. No significant heat-induced changes are observed in the case of the TaWOx-PEDOT:PSS HTL when annealed up to 120 °C, imparting enhanced thermal stability to the devices. Improved wettability on hydrophobic surfaces, combined with air processability and enhanced thermal stability makes TaWOx-PEDOT:PSS a promising HTL material for fabricating stable NFA solar cells using roll-to-roll compatible printing and coating methods.
  • A Universal Co-Solvent Evaporation Strategy Enables Direct Printing of Perovskite Single Crystals for Optoelectronic Device Applications

    Corzo Diaz, Daniel Alejandro; Wang, Tonghui; Gedda, Murali; Yengel, Emre; Khan, Jafar Iqbal; Li, Ruipeng; Niazi, Muhammad Rizwan; Huang, Zhengjie; Kim, Taesoo; Baran, Derya; Sun, Dali; Laquai, Frédéric; Anthopoulos, Thomas D.; Amassian, Aram (Advanced Materials, Wiley, 2022-01-10) [Article]
    Solution-processed metal halide perovskite single crystals (SCs) are in high demand for a growing number of emerging device applications due to their superior optoelectronic properties compared to polycrystalline thin films. However, the historical focus on thin film optoelectronic and photovoltaic devices explains the absence of methods suitable for facile, scalable and high throughput fabrication of precision-engineered and positioned SCs and arrays. Here, we present a universal co-solvent evaporation (CSE) strategy by which perovskite SCsand arrays are produced directly on substrates from individual drying droplets in a single step within minutes at room temperature. The CSE strategy successfully guides supersaturation of drying droplets to suppress all unwanted crystallization pathways and is shown to produce SCsof a wide variety of three-dimensional (3D), quasi-two dimensional (2D), and mixed cation/halideperovskites. The drying droplet approach works with commonly used solvents, making it universal. Importantly, the CSE strategy ensures the SC consumes the precursor in its entirety, leaving little to no residue on substrates, which is crucial for enabling fabrication of SC arrays on large areas via printing and coating techniques. We go on to demonstrate direct on-chip fabrication of 3D and quasi-2D perovskite photodetector devices with outstanding performance. Our approach shows that metal halide perovskite SCs can now be produced on substrates from a drying solution via a wide range of solution processing methods, including microprinting and scalable, high throughput coating methods.
  • Porous Ti3C2Tx MXene Membranes for Highly Efficient Salinity Gradient Energy Harvesting

    Hong, Seunghyun; El Demellawi, Jehad K.; Lei, Yongjiu; Liu, Zhixiong; Marzooqi, Faisal Al; Arafat, Hassan A.; Alshareef, Husam N. (ACS Nano, American Chemical Society (ACS), 2022-01-09) [Article]
    Extracting osmotic energy through nanoporous membranes is an efficient way to harvest renewable and sustainable energy using the salinity gradient between seawater and river water. Despite recent advances of nanopore-based membranes, which have revitalized the prospect of blue energy, their energy conversion is hampered by nanomembrane issues such as high internal resistance or low selectivity. Herein, we report a lamellar-structured membrane made of nanoporous Ti<sub>3</sub>C<sub>2</sub>T<sub><i>x</i></sub> MXene sheets, exhibiting simultaneous enhancement in permeability and ion selectivity beyond their inherent trade-off. The perforated nanopores formed by facile H<sub>2</sub>SO<sub>4</sub> oxidation of the sheets act as a network of cation channels that interconnects interplanar nanocapillaries throughout the lamellar membrane. The constructed internal nanopores lower the energy barrier for cation passage, thereby boosting the preferential ion diffusion across the membrane. A maximum output power density of the nanoporous Ti<sub>3</sub>C<sub>2</sub>T<sub><i>x</i></sub> MXene membranes reaches up to 17.5 W·m<sup>-2</sup> under a 100-fold KCl gradient at neutral pH and room temperature, which is as high as by 38% compared to that of the pristine membrane. The membrane design strategy employing the nanoporous two-dimensional sheets provides a promising approach for ion exchange, osmotic energy extraction, and other nanofluidic applications.
  • Scalable CMOS-BEOL compatible AlScN/2D Channel FE-FETs

    Kim, Kwan-Ho; Oh, Seyong; Fiagbenu, Merrilyn Mercy Adzo; Zheng, Jeffrey; Musavigharavi, Pariasadat; Kumar, Pawan; Trainor, Nicholas; Aljarb, Areej; Wan, Yi; Kim, Hyong Min; Katti, Keshava; Tang, Zichen; Tung, Vincent; Redwing, Joan; Stach, Eric A.; III, Roy H. Olsson; Jariwala, Deep (arXiv, 2022-01-06) [Preprint]
    Intimate integration of memory devices with logic transistors is a frontier challenge in computer hardware. This integration is essential for augmenting computational power concurrently with enhanced energy efficiency in big-data applications such as artificial intelligence. Despite decades of efforts, reliable, compact, energy efficient and scalable memory devices are elusive. Ferroelectric Field Effect Transistors (FE-FETs) are a promising candidate but their scalability and performance in a back-end-of-line (BEOL) process remain unattained. Here, we present scalable BEOL compatible FE-FETs using two-dimensional (2D) MoS2 channel and AlScN ferroelectric dielectric. We have fabricated a large array of FE-FETs with memory windows larger than 7.8 V, ON/OFF ratios of greater than 10^7, and ON current density greater than 250 uA/um, all at ~80 nm channel lengths. Our devices show stable retention up to 20000 secs and endurance up to 20000 cycles in addition to 4-bit pulse programmable memory features thereby opening a path towards scalable 3D hetero-integration of 2D semiconductor memory with Si CMOS logic.
  • 14 GHz Schottky Diodes using a p -Doped Organic Polymer

    Loganathan, Kalaivanan; Scaccabarozzi, Alberto D.; Faber, Hendrik; Ferrari, Federico; Bizak, Zhanibek; Yengel, Emre; Naphade, Dipti R.; Gedda, Murali; He, Qiao; Solomeshch, Olga; Adilbekova, Begimai; Yarali, Emre; Tsetseris, Leonidas; Salama, Khaled N.; Heeney, Martin; Tessler, Nir; Anthopoulos, Thomas D. (Advanced Materials, Wiley, 2022-01-06) [Article]
    The low carrier mobility of organic semiconductors and the high parasitic resistance and capacitance often encountered in conventional organic Schottky diodes, hinder their deployment in emerging radio frequency (RF) electronics. Here we overcome these limitations by combining self-aligned asymmetric nanogap electrodes (∼25 nm) produced by adhesion-lithography, with a high mobility organic semiconductor and demonstrate RF Schottky diodes able to operate in the 5G frequency spectrum. We used C<sub>16</sub> IDT-BT, as the high hole mobility polymer, and studied the impact of p-doping on the diode performance. Pristine C<sub>16</sub> IDT-BT-based diodes exhibit maximum intrinsic and extrinsic cutoff frequencies (f<sub>C</sub> ) of >100 and 6 GHz, respectively. This extraordinary performance is attributed primarily to the planar nature of the nanogap channel and the diode's small junction capacitance (< 2 pF). Doping of C<sub>16</sub> IDT-BT with the molecular p-dopant C<sub>60</sub> F<sub>48</sub> , improves the diode's performance further by reducing the series resistance resulting to intrinsic and extrinsic f<sub>C</sub> of >100 and ∼14 GHz respectively, while the DC output voltage of a RF rectifier circuit increases by a tenfold. Our work highlights the importance of the planar nanogap architecture and paves the way for the use of organic Schottky diodes in large-area radio frequency electronics of the future. This article is protected by copyright. All rights reserved.
  • Ultrahigh-flux Nanoporous Graphene Membrane for Sustainable Seawater Desalination Using Low-grade Heat

    Lu, Dongwei; Zhou, Zongyao; Wang, Zhihong; Ho, Duc Tam; Sheng, Guan; Chen, Long; Zhao, Yumeng; Li, Xiang; Cao, Li; Schwingenschlögl, Udo; Ma, Jun; Lai, Zhiping (Advanced Materials, Wiley, 2022-01-06) [Article]
    Membrane distillation has attracted great attention in the development of sustainable desalination and zero-discharge processes because of its possibility to recover 100% water and the potential to integrate with low-grade heat such as solar energy. However, the conventional membrane structures and materials afford limited flux thus obstructing its practical application. Here we report ultrathin nanoporous graphene membranes by selectively forming thin graphene layers on the top edges of highly porous anodic alumina oxide support, which creates short and fast transport pathways for water vapor but not liquid. The process avoids the challenging pore-generation and substrate-transfer processes required to prepare regular graphene membranes. In the direct contact membrane distillation mode under a mild temperature pair of 65°C /25°C, the nanoporous graphene membranes show an average water flux of 421.7 Lm<sup>-2</sup> h<sup>-1</sup> with over 99.8% salt rejection, which is an order of magnitude higher than any reported polymeric membranes. The mechanism for high water flux is revealed by detailed characterizations and theoretical modeling. Outdoor field tests using Red Sea water heated under direct sunlight radiation show that the membranes have an average water flux of 86.3 Lm<sup>-2</sup> h<sup>-1</sup> from 8 am. to 8 pm., showing a great potential for real applications in seawater desalination. This article is protected by copyright. All rights reserved.
  • Organic Acid Etching Strategy for Dendrite Suppression in Aqueous Zinc-Ion Batteries

    Wang, Wenxi; Huang, Gang; Wang, Yizhou; Cao, Zhen; Cavallo, Luigi; Hedhili, Mohamed N.; Alshareef, Husam N. (Advanced Energy Materials, Wiley, 2022-01-05) [Article]
    Aqueous zinc ion batteries (AZIBs) represent a promising technology for grid-scale energy storage due to their innate safety, low cost, and environmental friendliness. However, planar Zn foil intrinsically suffers from limited ion and electron transport pathways, poor wettability, and surface passivation, preventing the homogenous deposition of metallic Zn and poor durability of AZIBs. Herein, a 3D Zn foil with hierarchical porous architecture is developed through a facile non-aqueous organic acid etching strategy. The 3D Zn anode is pore-rich and cavity-rich, leading to significantly enhanced accessibility to aqueous electrolytes. Accordingly, this 3D Zn anode enables preferential plating of Zn in the porous texture with suppressed dendrite growth, as confirmed by ex situ scanning electron microscopy and finite element analysis. The cycle life of the 3D Zn anode is sustained over 930 and 1500 h at 4.0 mA cm−2-2.0 mAh cm−2 and 1.0 mA cm−2-1.0 mAh cm−2, respectively. Furthermore, the assembled 3D Zn and α-MnO2 full batteries demonstrate a prolonged cycle life of 3000 cycles with improved rate performance. The etching strategy using non-aqueous organic acid paves a new way to fabricate 3D metal anodes for Zn and other metal anode batteries.
  • Emerging Era of Electrolyte Solvation Structure and Interfacial Model in Batteries

    Cheng, Haoran; Sun, Qujiang; Li, Leilei; Zou, Yeguo; Wang, Yuqi; Cai, Tao; Zhao, Fei; Liu, Gang; Ma, Zheng; Wahyudi, Wandi; Li, Qian; Ming, Jun (ACS Energy Letters, American Chemical Society (ACS), 2022-01-02) [Article]
    Over the past two decades, the solid–electrolyte interphase (SEI) layer that forms on an electrode’s surface has been believed to be pivotal for stabilizing the electrode’s performance in lithium-ion batteries (LIBs). However, more and more researchers currently are realizing that the metal-ion solvation structure (e.g., Li+) in electrolytes and the derived interfacial model (i.e., the desolvation process) can affect the electrode’s performance significantly. Thus, herein we summarize recent research focused on how to discover the importance of an electrolyte’s solvation structure, develop a quantitative model to describe the solvation structure, construct an interfacial model to understand the electrode’s performance, and apply these theories to the design of electrolytes. We provide a timely review on the scientific relationship between the molecular interactions of metal ions, anions, and solvents in the interfacial model and the electrode’s performance, of which the viewpoint differs from the SEI interpretations before. These discoveries may herald a new, post-SEI era due to their significance for guiding the design of LIBs and their performance improvement, as well as developing other metal-ion batteries and beyond.
  • 'All In One' SARS-CoV-2 variant recognition platform: Machine learning-enabled point of care diagnostics

    Beduk, Duygu; Ilton de Oliveira Filho, José; Beduk, Tutku; Harmanci, Duygu; Zihnioglu, Figen; Cicek, Candan; Sertoz, Ruchan; Arda, Bilgin; Goksel, Tuncay; Turhan, Kutsal; Salama, Khaled N.; Timur, Suna (Biosensors and Bioelectronics: X, Elsevier BV, 2022-01) [Article]
    Point of care (PoC) devices are highly demanding to control current pandemic, originated from severe acute respiratory syndrome Coronavirus 2 (SARS-CoV-2). Though nucleic acid-based methods such as RT-PCR are widely available, they require sample preparation and long processing time. PoC diagnostic devices provide relatively faster and stable results. However they require further investigation to provide high accuracy and be adaptable for the new variants. In this study, laser-scribed graphene (LSG) sensors are coupled with gold nanoparticles (AuNPs) as stable promising biosensing platforms. Angiotensin Converting Enzyme 2 (ACE2), an enzymatic receptor, is chosen to be the biorecognition unit due to its high binding affinity towards spike proteins as a key-lock model. The sensor was integrated to a homemade and portable potentistat device, wirelessly connected to a smartphone having a customized application for easy operation. LODs of 5.14 and 2.09 ng/mL was achieved for S1 and S2 protein in the linear range of 1.0–200 ng/mL, respectively. Clinical study has been conducted with nasopharyngeal swabs from 63 patients having alpha (B.1.1.7), beta (B.1.351), delta (B.1.617.2) variants, patients without mutation and negative patients. A machine learning model was developed with accuracy of 99.37% for the identification of the SARS-Cov-2 variants under 1 min. With the increasing need for rapid and improved disease diagnosis and monitoring, the PoC platform proved its potential for real time monitoring by providing accurate and fast variant identification without any expertise and pre sample preparation, which is exactly what societies need in this time of pandemic.
  • Wafer-scale single-orientation 2D layers by atomic edge-guided epitaxial growth

    Wan, Yi; Fu, Jui-Han; Chuu, Chih-Piao; Tung, Vincent; Shi, Yumeng; Li, Lain-Jong (Chemical Society Reviews, Royal Society of Chemistry (RSC), 2022) [Article]
    Two-dimensional (2D) layered materials hold tremendous promise for post-Si nanoelectronics due to their unique optical and electrical properties. Significant advances have been achieved in device fabrication and synthesis routes for 2D nanoelectronics over the past decade; however, one major bottleneck preventing their immediate applications has been the lack of a reproducible approach for growing wafer-scale single-crystal films despite tremendous progress in recent experimental demonstrations. In this tutorial review, we provide a systematic summary of the critical factors—including crystal/substrate symmetry and energy consideration—necessary for synthesizing single-orientation 2D layers. In particular, we focus on the discussions of the atomic edge-guided epitaxial growth, which assists in unidirectional nucleation for the wafer-scale growth of single-crystal 2D layers.
  • Efficient generation of remarkably long-lived charges in organic semiconductor heterojunction nanoparticles enables high photocatalytic efficiency

    Kosco, Jan; Gonzalez-Carrero, Soranyel; Howells, Calvyn T.; Fei, Teng; Dong, Yifan; Sougrat, Rachid; Harrison, George T.; Firdaus, Yuliar; Sheelamanthula, Rajendar; Purushothaman, Balaji; Moruzzi, Floriana; Xu, Weidong; Zhao, Lingyun; Basu, Aniruddha; De Wolf, Stefaan; Anthopoulos, Thomas D.; Durrant, James R.; McCulloch, Iain (Accepted by Nature Energy, Springer Nature, 2022) [Article]
    There is a growing interest in developing organic semiconductor photocatalysts for the synthesis of solar fuels. Most organic photocatalysts rely on exciton dissociation by sacrificial reagents to drive charge separation. We demonstrate that organic semiconductor nanoparticle (NP) photocatalysts comprising the conjugated polymer PM6 matched with PCBM or Y6 electron acceptors can intrinsically generate remarkably long-lived reactive charges, which enable them to efficiently drive the H2 evolution reaction (HER). The optimized PM6:Y6 NPs achieved external quantum efficiencies (EQEs) of 1.0% to 5.0% at 400 to 900 nm and the optimized PM6:PCBM NPs achieved EQEs of 8.7% to 2.6% at 400 to 700 nm. Selective Pt photodeposition was observed on the PCBM domain in the PM6:PCBM NPs and its location was rationalized based on the location of photogenerated electrons in the heterojunction. Employing transient and operando photoinduced optical absorption spectroscopies on ps-s timescales, we find that the heterojunction structure in these NPs greatly enhances the generation of long-lived charges (ms-s timescale) even in the absence of electron/hole scavengers or Pt. The generation of such long-lived reactive charges is striking and opens potential applications for driving kinetically slow and technologically desirable oxidations, or in water splitting Z-schemes.
  • Aqueous Aluminum-Carbon Rechargeable Batteries

    Smajic, Jasmin; Hasanov, Bashir E.; Alazmi, Amira; Emwas, Abdul-Hamid M.; Wehbe, Nimer; Genovese, Alessandro; El Labban, Abdulrahman; Da Costa, Pedro M. F. J. (Advanced Materials Interfaces, Wiley, 2021-12-31) [Article]
    Carbon cathodes have shown excellent electrochemical behavior in aluminum batteries based on non-aqueous electrolytes. By contrast, their use in Al systems operating in a salt-water medium is plagued by poor and unstable performance. Herein, it is sustained that a successful C cathode for rechargeable aqueous Al batteries requires surface customization to enable hydrophilicity and grafting of charged Al molecules. Employing a freeze-dried reduced graphene oxide (rGO) as the active electrode material, an aqueous Al-C battery is assembled with a high energy density (136 Wh kg−1 per cathode mass) and one of the best capacity retentions reported (≈60% across a range of current densities and constant Coulombic efficiencies close to unit). Furthermore, the rGO cathode more than doubles the benchmark for life cycles (to ≈200 cycles) and can be charged rapidly (<5 min). To explain this response, a charge storage mechanism is proposed wherein the [Al(H2O)6]3+ ions do not get desolvated when inserted into the cathode. The guest Al ions (surface adsorbed or intercalated) act as proton donors and may get anchored on the oxygen moieties of the rGO, further promoting the formation of an electrochemical double layer. A mixed charge-storage regime follows that stabilizes the carbon cathode and enables an unprecedented response.
  • Inkjet Printing: A Cheap and Easy-to-Use Alternative to Wire Bonding for Academics

    Liu, Yingwen; Zhu, Kaichen; Hui, Fei; Yuan, Bin; Zhang, Chenhui; Ma, Yinchang; Zhang, Xixiang; Lanza, Mario (Crystal Research and Technology, Wiley, 2021-12-28) [Article]
    Many groups in academia are having problems patterning interconnections to small electrodes using wire bonding, including metal melting and detachment of previously bonded wires. It is a fact that the industry makes reliable wire bonding using automatic setups and expert personnel, and also that many groups in academia can do wire bonding reliably. However, it is also true that wire bonding is much more problematic than other techniques often employed to pattern interconnections, such as lithography or inkjet printing. In this article, the contact resistance and maximum currents driven by metallic interconnections patterned via wire bonding, lithography, and inkjet printing are compared. It is concluded that interconnections patterned via inkjet printing meet the requirements of many types of experiments, and that inkjet printing is a very cheap and easy-to-use alternative to wire bonding, especially attractive for academics.

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