Strategic Growth Area: Economical and Sustainable Materials (ESM)
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Browsing Strategic Growth Area: Economical and Sustainable Materials (ESM) by Department "Chemistry"
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- Amphiphilic hydroxyalkyl cellulose derivatives for amorphous solid dispersion prepared by olefin cross-metathesisDong, Yifan; Mosquera-Giraldo, Laura I.; Troutman, Jacob; Skogstad, Brittny; Taylor, Lynne S.; Edgar, Kevin J. (Royal Society of Chemistry, 2016-07-07)Olefin cross-metathesis (CM) has enabled design and synthesis of diverse, amphiphilic cellulose ether derivatives (e.g. of ethyl and methyl cellulose). In this paper, hydroxyalkyl cellulose was selected as a hydrophilic starting material, with the additional advantage that it has DS (OH) 3.0 that allows targeting of a full range of DS of selected functional groups. Hydroxypropyl cellulose (HPC) was first etherified with 5-bromopent-1-ene to attach olefin “handles” for metathesis, whereby control of molar ratios of sodium hydride and 5-bromopent-1-ene permits full DS control of appended olefin. These olefin-terminated HPC ethers then were subjected to CM with acrylic acid and different acrylates, followed by diimide hydrogenation to reduce the resulting α,β-unsaturation. NMR and FT-IR spectroscopies were useful tools for following reaction progress. One of the product carboxyl-functionalized HPC derivatives, designated HPC-Pen106-AA-H, showed high promise as a crystallization inhibitor of the antiviral drug telaprevir. Its nucleation-induction inhibitory ability was compared to those of commercial controls, HPC and HPMCAS. All three polymers were very effective for inhibiting telaprevir crystallization, increasing induction time up to 8-fold. HPC did not effectively prevent amorphous particle growth, whereas the carboxyl-containing HPC-Pen106-AA-H and HPMCAS were able to prevent formation of agglomerates of amorphous drugs.
- Biodegradable Poly(Lactic Acid) Nanocomposites for Fused Deposition Modeling 3D PrintingBardot, Madison; Schulz, Michael D. (MDPI, 2020-12-21)3D printing by fused deposition modelling (FDM) enables rapid prototyping and fabrication of parts with complex geometries. Unfortunately, most materials suitable for FDM 3D printing are non-degradable, petroleum-based polymers. The current ecological crisis caused by plastic waste has produced great interest in biodegradable materials for many applications, including 3D printing. Poly(lactic acid) (PLA), in particular, has been extensively investigated for FDM applications. However, most biodegradable polymers, including PLA, have insufficient mechanical properties for many applications. One approach to overcoming this challenge is to introduce additives that enhance the mechanical properties of PLA while maintaining FDM 3D printability. This review focuses on PLA-based nanocomposites with cellulose, metal-based nanoparticles, continuous fibers, carbon-based nanoparticles, or other additives. These additives impact both the physical properties and printability of the resulting nanocomposites. We also detail the optimal conditions for using these materials in FDM 3D printing. These approaches demonstrate the promise of developing nanocomposites that are both biodegradable and mechanically robust.
- Block copolymer derived uniform mesopores enable ultrafast electron and ion transport at highmass loadingsLiu, Tianyu; Zhou, Zhenping; Guo, Yichen; Guo, Dong; Liu, Guoliang (Nature Research, 2019)High mass loading and fast charge transport are two crucial but often mutually exclusive characteristics of pseudocapacitors. On conventional carbon supports, high mass loadings inevitably lead to sluggish electron conduction and ion diffusion due to thick pseudocapacitive layers and clogged pores. Here we present a design principle of carbon supports, utilizing self-assembly and microphase-separation of block copolymers. We synthesize porous carbon fibers (PCFs) with uniform mesopores of 11.7 nm, which are partially filled with MnO2 of <2 nm in thickness. The uniform mesopores and ultrathin MnO2 enable fast electron/ion transport comparable to electrical-double-layer-capacitive carbons. At mass loadings approaching 7mg cm−2, the gravimetric and areal capacitances of MnO2 (~50% of total mass) reach 1148 F g−1 and 3141 mF cm−2, respectively. Our MnO2-coated PCFs outperform other MnO2-based electrodes at similar loadings, highlighting the great promise of block copolymers for designing PCF supports for electrochemical applications.
- Boosting the Power-Generation Performance of Micro-Sized Al-H2O2 Fuel Cells by Using Silver Nanowires as the CathodeZhang, Heng; Yang, Yang; Liu, Tianyu; Chang, Honglong (MDPI, 2018-09-03)Micro-sized fuel cells represent one of the pollution-free devices available to power portable electronics. However, the insufficient power output limits the possibility of micro-sized fuel cells competing with other power sources, including supercapacitors and lithium batteries. In this study, a novel aluminum-hydrogen peroxide fuel cell is fabricated using uniform silver nanowires with diameters of 0.25 µm as the catalyst at the cathode side. The Ag nanowire solution is prepared via a polyol method, and mixed uniformly with Nafion and ethanol to enhance the adhesion of Ag nanowires. We carry out electrochemical tests, including cyclic voltammetry, electrochemical impedance spectroscopy, and Tafel polarization, to characterize the performance of this catalyst in H2O2 reduction. The Ag nanowires exhibit a high effectiveness and durability while catalyzing the reduction of H2O2 with a low impedance. The micro-sized Al-H2O2 fuel cell equipped with Ag nanowires delivers a power density of 43 W·m−2 under a low concentration of H2O2 (0.1 M), which is substantially higher than the previously reported devices.
- Controlling Morphological Parameters of Anodized Titania Nanotubes for Optimized Solar Energy ApplicationsHaring, Andrew J.; Morris, Amanda J.; Hu, Michael (MDPI, 2012-10-19)Anodized TiO2 nanotubes have received much attention for their use in solar energy applications including water oxidation cells and hybrid solar cells [dye-sensitized solar cells (DSSCs) and bulk heterojuntion solar cells (BHJs)]. High surface area allows for increased dye-adsorption and photon absorption. Titania nanotubes grown by anodization of titanium in fluoride-containing electrolytes are aligned perpendicular to the substrate surface, reducing the electron diffusion path to the external circuit in solar cells. The nanotube morphology can be optimized for the various applications by adjusting the anodization parameters but the optimum crystallinity of the nanotube arrays remains to be realized. In addition to morphology and crystallinity, the method of device fabrication significantly affects photon and electron dynamics and its energy conversion efficiency. This paper provides the state-of-the-art knowledge to achieve experimental tailoring of morphological parameters including nanotube diameter, length, wall thickness, array surface smoothness, and annealing of nanotube arrays.
- Cooperative electrochemical water oxidation by Zr nodes and Ni–porphyrin linkers of a PCN-224 MOF thin filmUsov, Pavel M.; Ahrenholtz, Spencer Rae; Maza, William A.; Stratakes, Bethany; Epley, Charity Cherie; Kessinger, Matthew C.; Zhu, Jie; Morris, Amanda J. (Royal Society of Chemistry, 2016-10-06)Here, we demonstrate a new strategy for cooperative catalysis and proton abstraction via the incorporation of independent species competent in the desired reactivity into a metal–organic framework (MOF) thin film. The highly porous MOF, designated as PCN-224-Ni, is constructed by Zr–oxo nodes and nickel(II) porphyrin linkers. Films of PCN-224-Ni were grown in situ on FTO and were found to electrochemically facilitate the water oxidation reaction at near neutral pH.
- Double helical conformation and extreme rigidity in a rodlike polyelectrolyteWang, Ying; He, Yadong; Yu, Zhou; Gao, Jianwei; ten Brinck, Stephanie; Slebodnick, Carla; Fahs, Gregory B.; Zanelotti, Curt J.; Hegde, Maruti; Moore, Robert Bowen; Ensing, Bernd; Dingemans, Theo J.; Qiao, Rui; Madsen, Louis A. (Nature Publishing Group, 2019-02-18)The ubiquitous biomacromolecule DNA has an axial rigidity persistence length of ~50 nm, driven by its elegant double helical structure. While double and multiple helix structures appear widely in nature, only rarely are these found in synthetic non-chiral macromolecules. Here we report a double helical conformation in the densely charged aromatic polyamide poly(2,2′-disulfonyl-4,4′-benzidine terephthalamide) or PBDT. This double helix macromolecule represents one of the most rigid simple molecular structures known, exhibiting an extremely high axial persistence length (~1 micrometer). We present X-ray diffraction, NMR spectroscopy, and molecular dynamics (MD) simulations that reveal and confirm the double helical conformation. The discovery of this extreme rigidity in combination with high charge density gives insight into the self-assembly of molecular ionic composites with high mechanical modulus (~ 1 GPa) yet with liquid-like ion motions inside, and provides fodder for formation of other 1D-reinforced composites. © 2019, The Author(s).
- Exceptional capacitive deionization rate and capacity by block copolymer–based porous carbon fibersLiu, Tianyu; Serrano, Joel; Elliott, John; Yang, Xiaozhou; Cathcart, William; Wang, Zixuan; He, Zhen; Liu, Guoliang (American Association for the Advancement of Science, 2020-04-17)Capacitive deionization (CDI) is energetically favorable for desalinating low-salinity water. The bottlenecks of current carbon-based CDI materials are their limited desalination capacities and time-consuming cycles, caused by insufficient ion-accessible surfaces and retarded electron/ion transport. Here, we demonstrate porous carbon fibers (PCFs) derived from microphase-separated poly(methyl methacrylate)-block-polyacrylonitrile (PMMA-b-PAN) as an effective CDI material. PCF has abundant and uniform mesopores that are interconnected with micropores. This hierarchical porous structure renders PCF a large ion-accessible surface area and a high desalination capacity. In addition, the continuous carbon fibers and interconnected porous network enable fast electron/ion transport, and hence a high desalination rate. PCF shows desalination capacity of 30 mgNaCl g⁻¹ PCF and maximal time-average desalination rate of 38.0 mgNaCl g⁻¹ PCF min⁻¹, which are about 3 and 40 times, respectively, those of typical porous carbons. Our work underlines the promise of block copolymer–based PCF for mutually high-capacity and high-rate CDI.
- Fabrication of Nanostructured Kaolinite Doped Composite Films from Silicone Rubber with Enhanced PropertiesZakaria, Abdullah Muhammad; Dey, Shaikat Chandra; Rahman, Muhammad Mominur; Sarker, Mithun; Ashaduzzaman, Md.; Shamsuddin, Sayed Md. (MDPI, 2019-05-12)Naturally occurring nanomaterials are finding growing interests in tailoring properties of engineering polymers for advanced applications. The objective of this study was to develop environment-friendly nanocomposite films by reinforcing kaolinite nanofillers (1–10 wt%) in silicone rubber (SR) matrix using a simple solvent casting technique. Kaolinite-reinforced films showed substantial improvement in mechanical (tensile strength, Young’s modulus, and elongation at break) and thermal properties at very low filler loading (5 wt%). The improvement of solvent resistance nature of the fabricated films was another critical aspect of this study. Unfilled SR film showed ~19% weight loss when immersed in toluene for 4 h at 25 °C, whereas only ~4% weight loss was recorded in the case of 5% (w/w) kaolinite loaded film. Therefore, kaolinite has the potential to bring significant improvement in the properties of SR. This study indicates that there is plenty of room at the bottom for proper utilization of the potential of kaolinite for developing SR-based composite materials for potential applications in many industries, such as textile, household cleaning, construction, electronics, automotive, medical, etc.
- High-performance inertial impaction filters for particulate matter removalZhang, Xiaowei; Zhang, Wei; Yi, Mingqiang; Wang, Yingjie; Wang, Pengjun; Xu, Jun; Niu, Fenglei; Lin, Feng (Springer Nature, 2018-03-19)Airborne particulate matter (PM) is causing more and more serious air pollution and threatening the public health. However, existing air filter technologies with the easy-to-block manner can rarely meet the requirements of high-performance PM filters. Here we propose a conceptually new type of inertial impaction filters for rapidly high-efficiency PM removal. Under the airflow velocity of 8.0 m/s, the real inertial impaction filters show high PM removal efficiencies of up to 97.77 +/- 1.53% and 99.47 +/- 0.45% for PM2.5 and PM10, respectively. Compared with the traditional air filters reported previously, the inertia impaction filters exhibit extremely low pressure drop of 5-10 Pa and high quality factor (QF) values of 0.380 Pa-1 and 0.524 Pa-1 for PM2.5 and PM10, respectively. These greatly improved QF values are achieved through a series of inertial separation processes. The feature dimension of filtration channel is dozens of times larger than PM average size, which greatly decreases airflow resistance. Particularly, this inertial structure can be made of various types of materials, which shows great potential for low-cost fabrication of large-area devices. As a stand-alone device or incorporated with the existing PM air filter, this inertial impaction filter will bring great benefits to the public health.
- Imparting functional variety to cellulose ethers via olefin cross-metathesisDong, Yifan; Edgar, Kevin J. (The Royal Society of Chemistry, 2015-04-09)Olefin cross-metathesis is a valuable new approach for imparting functional variety to cellulose ethers. Starting from commercially available ethyl cellulose, terminally unsaturated alkyl groups were appended as metathesis handles by reaction with allyl chloride, 5-bromo-1-pentene, 7-bromo-1-heptene and 11-bromo-1-undecene, employing sodium hydride catalyst. These olefin-terminal ethyl cellulose derivatives were then subjected to olefin cross-metathesis with a variety of electron-poor olefin substrates, including acrylic acid and acrylate esters under optimized conditions (5–10 mol% Hoveyda-Grubbs’ 2nd generation catalyst, 37 °C, 2 h). The effects of varying the length of the ω-unsaturated alkyl handle, and of the solvent systems used were evaluated. Ethyl cellulose containing a pent-4-enyl substituent performed best in cross metathesis reactions and a hept-6-enyl substituent gave similarly good results. Ethyl cellulose with allyl substituents gave low to moderate metathesis conversion (<50%), possibly due to steric effects and the proximity of the ether oxygen to the terminal olefin. Interestingly, longer tethers (undec-10-enyl) gave high conversions (up to 90%) but relatively slow reactions (ca. 12 h needed for high conversion). While limited in this study by the relatively low DS (OH) of the starting commercial ethyl cellulose materials, this methodology has strong promise for introduction of diverse functionality to cellulose ethers in chemospecific and mild fashion, enabling amorphous solid dispersion and other applications.
- Influence of nucleobase stoichiometry on the self-assembly of ABC triblock copolymersZhang, Keren; Talley, Samantha J.; Yu, Ya Peng; Moore, Robert Bowen; Murayama, Mitsuhiro; Long, Timothy E. (Royal Society of Chemistry, 2016-05-11)ABC triblock copolymers bearing adenine- and thymine-functionalized external blocks self-assembled into long-range, ordered lamellar microphase-separated morphologies on non-patterned substrates. Intermolecular hydrogen bonding formed thymine–adenine triplets and promoted self-assembly into well-defined lamellae consisting of poly(n-butyl acrylate) soft domains and complementary nucleobase hard domains, while thymine–adenine duplets contributed to superior mechanical properties.
- Multifunctional cellulose esters by olefin cross-metathesis and thiol-Michael additionMeng, Xiangtao; Roy Choudhury, Shreya; Edgar, Kevin J. (Royal Society of Chemistry, 2016-04-25)Olefin cross-metathesis (CM) has been shown to be a versatile, mild, modular, and efficient approach to polysaccharide modification. One issue with regard to this approach is the susceptibility of the initial α,β-unsaturated CM derivatives to H-atom abstraction in the γ-position, followed by radical recombination that leads to insoluble, crosslinked products. In our original approach, we resolved this problem through removing the offending unsaturation by hydrogenation. In the current study, we describe a method to exploit these reactive conjugated olefins, by post-CM thiol-Michael addition, thereby appending additional functionality. CM substrates and thiols bearing various functional groups were combined and reacted, employing amine catalysis. Up to 100% conversion was achieved under proper conditions (e.g. catalyst and reaction time), with minimal side reactions observed. The combination of the two modular reactions creates versatile access to cellulose derivatives equipped with a wide diversity of functional groups.
- Non-isocyanate poly(amide-hydroxyurethane)s from sustainable resourcesZhang, Keren; Nelson, Ashley M.; Talley, Samantha J.; Chen, Mingtao; Margaretta, Evan; Hudson, Amanda G.; Moore, Robert Bowen; Long, Timothy E. (Royal Society of Chemistry, 2016-05-19)A two-step synthesis of epoxidation and carbonation afforded a hetero-functional AB monomer with cyclic carbonate and methyl ester (CC-ME) using plant oil-based methyl 9-decenoate and CO2. A unprecedented one-pot synthetic platform of CC-ME with 1,12-diaminododecane and poly(tetramethylene oxide) (PTMO)-based polyether diamine allowed synthesis of both nonsegmented poly(amide-hydroxyurethane) (PA12HU) and segmented PA12HU-PTMOs with varying polyether contents. 1H NMR spectroscopy confirmed complete conversion of cyclic carbonates and methyl esters to hydroxyurethanes and amides, respectively. Thermal analysis revealed distinctive thermal stability and transitions of PA12HU and PA12HU-PTMOs compared to their precursors and model oligomers. PA12HU and PA12HU-PTMOs were melt compression molded into semicrystalline, free-standing films, except for PA12HU-PTMO100 with 100% polyether diamine. PA12HU-PTMO100 was a viscous liquid with a glass transition temperature (Tg) of −64 °C and zero-shear melt viscosity of 449 Pa s. PA12HU formed a semicrystalline, rigid film with Tg of 11 °C. Polyether incorporation afforded creasable PA12HU-PTMO films with broad glass transitions near −50 °C. Thermal and thermomechanical analysis revealed significant phase-mixing of the hard and soft segments from annealed PA12HU-PTMO films. Polyether soft segments mixed with the amorphous hard segments, forming a miscible soft phase; crystallizable hard segments with ordered hydrogen bonding formed a hard phase. Surface morphological analysis of each PA12HU-PTMO film displayed ribbon-like, hard domains with composition-dependent aspect ratios. PA12HU-PTMOs exhibited higher moisture uptake than traditional thermoplastic polyurethane (TPU) due to resultant hydroxyls. Variable temperature FTIR spectroscopy demonstrated that ordered hydrogen bonding in the crystalline domains was disrupted or dissociated as the crystallites melted. Although tensile strength of segmented PA12HU-PTMOs proved lower than traditional polyurethanes due to phase-mixing, these compositions represent the first examples of film-forming, linear isocyanate-free polyurethanes with mechanical integrity and processability.
- Novel Electrospun Pullulan Fibers Incorporating Hydroxypropyl-β-Cyclodextrin: Morphology and Relation with Rheological PropertiesPoudel, Deepak; Swilley-Sanchez, Sarah; O'Keefe, Sean F.; Matson, John B.; Long, Timothy E.; Fernández-Fraguas, Cristina (MDPI, 2020-10-31)Fibers produced by electrospinning from biocompatible, biodegradable and naturally occurring polymers have potential advantages in drug delivery and biomedical applications because of their unique functionalities. Here, electrospun submicron fibers were produced from mixtures containing an exopolysaccharide (pullulan) and a small molecule with hosting abilities, hydroxypropyl-β-cyclodextrin (HP-β-CD), thus serving as multi-functional blend. The procedure used water as sole solvent and excluded synthetic polymers. Rheological characterization was performed to evaluate the impact of HP-β-CD on pullulan entanglement concentration (CE); the relationship with electrospinnability and fiber morphology was investigated. Neat pullulan solutions required three times CE (~20% w/v pullulan) for effective electrospinning and formation of bead-free nanofibers. HP-β-CD (30% w/v) facilitated electrospinning, leading to the production of continuous, beadless fibers (average diameters: 853-1019 nm) at lower polymer concentrations than those required in neat pullulan systems, without significantly shifting the polymer CE. Rheological, Differential Scanning Calorimetry (DSC) and Dynamic Light Scattering (DLS) measurements suggested that electrospinnability improvement was due to HP-β-CD assisting in pullulan entanglement, probably acting as a crosslinker. Yet, the type of association was not clearly identified. This study shows that blending pullulan with HP-β-CD offers a platform to exploit the inherent properties and advantages of both components in encapsulation applications.
- Nucleobase-Functionalized ABC Triblock Copolymers: Self-assembly of Supramolecular ArchitecturesZhang, Keren; Fahs, Gregory B.; Aiba, Motohiro; Moore, Robert Bowen; Long, Timothy E. (The Royal Society of Chemistry, 2014-06-24)RAFT polymerization afforded acrylic ABC triblock copolymers with self-complementary nucleobase-functionalized external blocks and a low-Tg soft central block. ABC triblock copolymers self-assembled into well-defined lamellar microphase-separated morphologies for potential applications as thermoplastic elastomers. Complementary hydrogen bonding within the hard phase facilitated self-assembly and enhanced mechanical performance.
- Porous organic materials offer vast future opportunitiesLiu, Tianyu; Liu, Guoliang (2020-10-02)In light of the surging research on porous organic materials, we herein discuss the key issues of their porous structures, surface properties, and end functions. We also present an outlook on emerging opportunities, new applications, and data science-assisted materials discovery.
- Ruthenium(ii)-polypyridyl zirconium(iv) metal-organic frameworks as a new class of sensitized solar cellsMaza, William A.; Haring, Andrew J.; Ahrenholtz, Spencer Rae; Epley, Charity Cherie; Lin, Shaoyang; Morris, Amanda J. (The Royal Society of Chemistry, 2015-10-16)A series of Ru(II)L2L′ (L = 2,2′-bipyridyl, L′ = 2,2′-bipyridine-5,5′-dicarboxylic acid), RuDCBPY, -containing zirconium(IV) coordination polymer thin films have been prepared as sensitizing materials for solar cell applications. These metal–organic framework (MOF) sensitized solar cells, MOFSCs, each are shown to generate photocurrent in response to simulated 1 sun illumination. Emission lifetime measurements indicate the excited state quenching of RuDCBPY at the MOF–TiO2 interface is extremely efficient (>90%), presumably due to electron injection into TiO2. A mechanism is proposed in which RuDCBPY-centers photo-excited within the MOF-bulk undergo isotropic energy migration up to 25 nm from the point of origin. This work represents the first example in which a MOFSC is directly compared to the constituent dye adsorbed on TiO2 (DSC). Importantly, the MOFSCs outperformed their RuDCBPY–TiO2 DSC counterpart under the conditions used here and, thus, are solidified as promising solar cell platforms.
- Stereoselective photoredox ring-opening polymerization of O-carboxyanhydridesFeng, Quanyou; Yang, Lei; Zhong, Yongliang; Guo, Dong; Liu, Guoliang; Xie, Linghai; Huang, Wei; Tong, Rong (Nature, 2018-04-19)Biodegradable polyesters with various tacticities have been synthesized by means of stereoselective ring-opening polymerization of racemic lactide and β-lactones but with limited side-chain groups. However, stereoselective synthesis of functional polyesters remains challenging from O-carboxyanhydrides that have abundant pendant side-chain functional groups. Herein we report a powerful strategy to synthesize stereoblock polyesters by stereoselective ring-opening polymerization of racemic O-carboxyanhydrides with the use of photoredox Ni/Ir catalysts and a selected Zn complex with an achiral ligand. The obtained stereoblock copolymers are highly isotactic with high molecular weights ( > 70 kDa) and narrow molecular weight distributions (Mw/Mn < 1.1), and they display distinct melting temperatures that are similar to their stereocomplex counterparts. Furthermore, in one-pot photoredox copolymerization of two different O-carboxyanhydrides, the use of such Zn complex mediates kinetic resolution of the comonomers during enchainment and shows a chirality preference that allows for the synthesis of gradient copolymers.
- Ultrahigh Durability Perovskite Solar CellsWu, Congcong; Wang, Kai; Feng, Xu; Jiang, Yuanyuan; Yang, Dong; Hou, Yuchen; Yan, Yongke; Sanghadasa, Mohan; Priya, Shashank (American Chemical Society, 2019-01-29)Unprecedented conversion efficiency has been demonstrated for perovskite solar cells (PSCs), however, their stability and reliability continue to be challenge. Here, an effective and practical method is demonstrated to overcome the device stability issues in PSCs. A CF4 plasma treatment method is developed that results in the formation of a robust C–Fx layer covering the PSC device, thereby, imparting protection during the operation of solar cell. PSCs exposed to fluorination process showed excellent stability against water, light, and oxygen, displaying relatively no noticeable degradation after being dipped into water for considerable time period. The fluorination process did not have any impact on the morphology and electrical property of the top Spiro-OMeTAD layer, resulting in a conversion efficiency of 18.7%, which is identical to that of the pristine PSC. Under the continuous Xe lamp (AM 1.5G, 1 sun) illumination in ambient air for 100 h, the fluorinated PSCs demonstrated 70% of initial conversion efficiency, which is 4000% higher than that of the pristine PSC devices. We believe this breakthrough will have significant impact on the transition of PSCs into real world applications.