Showing papers by "Xiong Gong published in 2022"

High‐Performance Ternary Perovskite–Organic Solar Cells

Abstract: Perovskite solar cells in which 2D perovskites are incorporated within a 3D perovskite network exhibit improved stability with respect to purely 3D systems, but lower record power conversion efficiencies (PCEs). Here, a breakthrough is reported in achieving enhanced PCEs, increased stability, and suppressed photocurrent hysteresis by incorporating n‐type, low‐optical‐gap conjugated organic molecules into 2D:3D mixed perovskite composites. The resulting ternary perovskite–organic composites display extended absorption in the near‐infrared region, improved film morphology, enlarged crystallinity, balanced charge transport, efficient photoinduced charge transfer, and suppressed counter‐ion movement. As a result, the ternary perovskite–organic solar cells exhibit PCEs over 23%, which are among the best PCEs for perovskite solar cells with p–i–n device structure. Moreover, the ternary perovskite–organic solar cells possess dramatically enhanced stability and diminished photocurrent hysteresis. All these results demonstrate that the strategy of exploiting ternary perovskite–organic composite thin films provides a facile way to realize high‐performance perovskite solar cells.

Recent progress in the all‐solid‐state flexible supercapacitors

Abstract: In the past few years, supercapacitors (SCs) have attracted great attention in both academic and industrial sectors due to their high energy storage efficiency, reliable stability, and eco‐friendly process. Flexible solid‐state SCs as one of the ongoing focuses for the development of wearable and portable electronics have become the most promising energy storage devices for the smart power system due to their high power density, fast electrochemical response, high efficiency on the charge‐discharge process, and excellent electrochemical stability. In this study, the recent progress in the electrodes and electrolytes used for approaching high‐performance of the all‐solid‐state flexible SCs is reviewed. We first introduce basic operational principles of various SCs. And then we overview the electrode materials including carbon materials, conducting polymers, transition metal oxides/chalcogenides/nitrides, MXenes, metal‐organic frameworks, covalent‐organic frameworks, and the polymer‐based solid‐state electrolytes in different systems. Afterward, we summarize recent progress in the development of the all‐solid‐state flexible SCs and outlook for future research directions.

Efficient and Stable Perovskite Solar Cells by B-Site Compositional Engineered All-Inorganic Perovskites and Interface Passivation.

Abstract: Perovskite solar cells (PSCs) have emerged as a cost-effective solar technology in the past years. PSCs by three-dimensional hybrid inorganic-organic perovskites exhibited decent power conversion efficiencies (PCEs); however, their stabilities were poor. On the other hand, PSCs by all-inorganic perovskites indeed exhibited good stability, but their PCEs were low. Here, the development of novel all-inorganic perovskites CsPbI2Br:xNd3+, where Pb2+ at the B-site is partially heterovalently substituted by Nd3+, is reported. The CsPbI2Br:xNd3+ thin films possess enlarged crystal sizes, enhanced charge carrier mobilities, and superior crystallinity. Thus, the PSCs by the CsPbI2Br:xNd3+ thin films exhibit more than 20% enhanced PCEs and dramatically boosted stability compared to those based on pristine CsPbI2Br thin films. To further boost the device performance of PSCs, solution-processed 4-lithium styrenesulfonic acid/styrene copolymer (LiSPS) is utilized to passivate the surface defect and suppress surface charge carrier recombination. The PSCs based on the CsPbI2Br:xNd3+/LiSPS bilayer thin film possess reduced charge extraction lifetime and suppressed charge carrier recombination, resulting in 14% enhanced PCEs and significantly boosted stability compared to those without incorporation of the LiSPS interface passivation layer. All these results indicate that we developed a facile way to approach high-performance PSCs by all-inorganic perovskites.

Solution-Processed Ternary Perovskite-Organic Broadband Photodetectors with Ultrahigh Detectivity.

Abstract: Room temperature operated, solution-processed ultrasensitive broadband photodetectors are widely used in various industrial companies in the scientific and medical sectors. Herein, we report solution-processed ultrahigh detectivity broadband photodetectors based on the ternary perovskite-organic composites. To ensure the photodetector based on perovskites has a photoresponse from the ultraviolet-visible to the near-infrared (NIR) region, low optical gap n-type conjugated organic molecules are incorporated with the three-dimensional (3D) perovskites mixed with the two-dimensional (2D) perovskites to form the ternary perovskite-organic composites, which possess an extended spectral response up to the NIR region and superior film characteristics compared to the 2D-3D mixed perovskite composites. Moreover, the photodetectors based on the ternary perovskite-organic composites exhibit enhanced photocurrent and suppressed dark current compared to those based on the 2D/3D mixed perovskite composites. As a result, at room temperature, the photodetectors based on the ternary perovskite-organic composites exhibit a spectral response from 375 to 1000 nm, whereas the photodetectors based on the 2D-3D mixed perovskite composites exhibit a spectral response from 375 to 800 nm. Furthermore, the photodetectors based on the ternary perovskite-organic composites have a photodetectivity over 1015 cm Hz1/2 W-1 (Jones) in the ultraviolet-visible region and over 1013 Jones in the NIR region, a linear dynamic range over 110 dB, and a fast response time. All these results demonstrate that we developed a facile way to realize uncooled solution-processed ultrahigh detectivity broadband photodetectors based on the ternary perovskite-organic composites.

Formulating Zwitterionic, Responsive Polymers for Designing Smart Soils.

Abstract: The design of new remediation strategies and materials for treating saline-alkaline soils is of fundamental and practical importantance for many applications. Conventional soil remediation strategies mainly focus on the development of fertilizers or additives for water, nutrient, and heavy metal managements in soils, but they often overlook a soil sensing function for early detection of salinization/alkalization levels toward optimal and timely soil remediation. Here, new smart soils, structurally consisting of the upper signal soil and the bottom hygroscopic bed and chemically including zwitterionic, thermo-responsive poly(NIPAM-co-VPES) and poly(NIPAM-co-SBAA) aerogels in each soil layer are formulated. Upon salinization, the resultant smart soils exhibit multiple superior capacities for reducing the soil salinity and alkalinity through ion exchange, controlling the water cycling, modulating the degradation of pyridine-base ligands into water-soluble, nitrogenous salts-rich ingredients for soil fertility, and real-time monitoring salinized soils via pH-induced allochroic color changes. Further studies of plant growth in smart soils with or without salinization treatments confirm a synergy effect of soil remediation and soil sensing on facilitating the growth of plants and increasing the saline-alkaline tolerance of plants. The esign concept of smart soils can be further expanded for soil remediation and assessment.

Dual‐Functional, Multi‐Targeting GNNQQNY‐AIE Conjugates as Amyloid Probes and Amyloid Modulators via Amyloid Cross‐Seeding Principle

Abstract: Amyloid protein aggregation is associated with many neurodegenerative diseases, including amyloid‐β (Aβ) in Alzheimer disease, human islet amyloid polypeptide (hIAPP) in type II diabetes, and human calcitonin (hCT) in medullary thyroid carcinoma. Significant efforts have been made to develop different diagnostic and prevention strategies for the early detection and intervention of these disease‐causative protein aggregates. However, conventional design wisdoms are mostly limited to the molecules with either single function (amyloid imaging or amyloid prevention) or single targeting protein (Aβ, hIAPP, or hCT). Here, a rational design strategy of an amyloid‐aggregation‐induced emission (AIE)‐active molecule is demonstrated by conjugating an amyloid fragment of GNNQQNY (G7) with an AIE fluorescent molecule of triphenylvinyl benzoic acid (namely, G7‐TBA), making G7‐TBA as multiple‐target, dual‐function, amyloid probes and amyloid modulators for detecting, monitoring, and altering amyloid aggregation of three different amyloid proteins (Aβ, hIAPP, and hCT). G7‐TBA probe shows conformationally specific binding affinities to amyloid aggregates, switching from an “off” state (low fluorescence) for amyloid monomers to an “on” state (high fluorescence) for β‐structure‐rich amyloid oligomers and fibrils in aqueous solution. Further surface immobilization of TBA probes on surface plasmon resonance surfaces allows to amplify detection sensitivity and binding affinity to amyloid aggregates formed at different aggregation stages. G7‐TBA as amyloid modulator enables acceleration of amyloid fibrillization and selectively protects cells from hIAPP‐induced toxicity. The distinct amyloid detection and modulation of G7‐TBA are essentially derived from the cross‐seeding between G7 and amyloid aggregation via β‐structure interaction, which by far exceed the binding affinity between commercial ThT and amyloid aggregates. Such design concepts of amyloid‐AIE conjugates can be further explored as multiple‐function and target probes and/or modulators for biomedical applications.

High‐Performance Perovskite Photovoltaics by Heterovalent Substituted Mixed Perovskites

Abstract: 2D perovskites are relatively stable but possess poor charge transport compared to 3D perovskites. To boost charge transport, novel 2D perovskites mixed with 3D perovskites are developed, where Pb2+ are partially substituted by the heterovalent neodymium cations (Nd3+) within both 2D and 3D perovskites (termed Nd3+‐substituted 2D:3D mixed perovskites. Systematical studies reveal that the Nd3+‐substituted 2D:3D mixed perovskites possess larger crystals, superior crystallinity, suppressed non‐radiative charge recombination, and enhanced and balanced charge transport compared to the 2D:3D mixed perovskites. As a result, perovskite photovoltaics based on the Nd3+‐substituted 2D:3D mixed perovskites exhibit a power conversion efficiency of 22.11%, a photoresponsibility of over 700 mA W−1, a photodetectivity of 4.29 × 1014 cm Hz1/2 W−1, a linear dynamic range of 165 dB at room temperature, and dramatically boosted stability. These results demonstrate that, a facile way is developed to realize high‐performance perovskite photovoltaics through partially heterovalent substituted Pb2+ by Nd3+ within 2D:3D mixed perovskites.

Repurposing of intestinal defensins as multi-target, dual-function amyloid inhibitors via cross-seeding

Abstract: Amyloid formation and microbial infection are the two common pathological causes of neurogenerative diseases, including Alzheimer's disease (AD), type II diabetes (T2D), and medullary thyroid carcinoma (MTC). While significant efforts have been made to develop different prevention strategies and preclinical hits for these diseases, conventional design strategies of amyloid inhibitors are mostly limited to either a single prevention mechanism (amyloid cascade vs. microbial infection) or a single amyloid protein (Aβ, hIAPP, or hCT), which has prevented the launch of any successful drug on the market. Here, we propose and demonstrate a new “anti-amyloid and anti-bacteria” strategy to repurpose two intestinal defensins, human α-defensin 6 (HD-6) and human β-defensin 1 (HBD-1), as multiple-target, dual-function, amyloid inhibitors. Both HD-6 and HBD-1 can cross-seed with three amyloid peptides, Aβ (associated with AD), hIAPP (associated with T2D), and hCT (associated with MTC), to prevent their aggregation towards amyloid fibrils from monomers and oligomers, rescue SH-SY5Y and RIN-m5F cells from amyloid-induced cytotoxicity, and retain their original antimicrobial activity against four common bacterial strains at sub-stoichiometric concentrations. Such sequence-independent anti-amyloid and anti-bacterial functions of intestinal defensins mainly stem from their cross-interactions with amyloid proteins through amyloid-like mimicry of β-sheet associations. In a broader view, this work provides a new out-of-the-box thinking to search and repurpose a huge source of antimicrobial peptides as amyloid inhibitors, allowing the blocking of the two interlinked pathological pathways and bidirectional communication between the central nervous system and intestines via the gut–brain axis associated with neurodegenerative diseases.

Solution-processed broadband photodetectors without transparent conductive oxide electrodes

Abstract: Room-temperature operated photodetectors without transparent conductive oxide electrodes by conjugated polymers mixed with conductive inorganic quantum dots, exhibiting the detectivities over 10 12 Jones from 300 nm to 2000 nm, were demonstrated.

Blade Coating Inverted Perovskite Solar Cells with Vacuum‐Assisted Nucleation Based on Bottom Quasi‐2D Passivation

Abstract: Metal halide perovskite solar cells (PSCs) attract an enormous attention because of their high power conversion efficiency (PCE) and low fabrication cost. However, their commercialization is limited by fabricating highly efficient large‐area solar cells. Controlling the morphology and crystallization of perovskite for large‐area fabrication is difficult but important. Herein, a vacuum‐assisted approach is developed to obtain mirror‐like, pinhole‐free, highly crystalline, and uniform blade‐coated perovskite films, without the use of antisolvent and air knife. This method can be a universal approach for various perovskite compositions. Meanwhile, the phenethylammonium iodide passivation effect at the top and bottom interfaces of perovskite layer based on FTO/NiOx/perovskite/C60/BCP/Cu inverted p‐i‐n structure is systematically investigated. The optimized device fabricated by blade coating under an ambient environment exhibits the champion PCE of 20.7% and is among the top few records of blade coating inverted structure based on NiOx hole transport layer. The encapsulated device retains 97% of its maximum efficiency under open‐circuit condition after 1000 h of photostability test in an ambient environment at room temperature with a relative humidity of 40–60%. Herein, low‐cost, easy, and reproducible strategies to fabricate efficient and stable blade‐coated PSCs are demonstrated.

Origins of the Photocurrent Multiplication Effect in the Polythiophene-based Photodetectors.

Abstract: The photocurrent multiplication (PM) effect has been used to boost the device performance of polymer-based photodetectors (PDs), but its origin was rarely addressed. In this study, we report the origins of the PM effect in polymer PDs based on the P3HT:PC71 BM bulk heterojunction (BHJ) composite thin film, where P3HT is poly(3-hexylthiophene), and PC71 BM is [6,6]phenyl-C71 -butyric acid methyl ester, through both computational simulation and experimental investigation. Systematically studies indicate that two key factors play an important role in the realization of the PM effect in polymer PDs. One factor is the work function of the metal electrode, and another is the PC71 BM aggregations at the interface between the P3HT:PC71 BM BHJ composite thin film and the metal electrode. Moreover, the results from both experimental and computational simulation indicate that the values of the current density under the light illumination minus the current density in the dark of polymer PDs are increased simultaneously along with the reduction of the thickness of the P3HT:PC71 BM BHJ composite thin film. Our results provide an understanding of the PM effect in polymer PDs and the guidance for the development of high-performance polymer PDs based on BHJ composite thin film. This article is protected by copyright. All rights reserved.

Effect of External Magnetic Field on Bulk Heterojunction Polymer Solar Cells.

Abstract: Polymer solar cells (PSCs) with a bulk heterojunction (BHJ) device structure have incredible advantages, such as low-cost fabrication and flexibility. But, the power conversion efficiency (PCE) of BHJ PSCs needs to be further improved to realize their practical applications. In this study, we report boosted PCEs from the PSCs based on the BHJ composites incorporated with Fe3 O4 magnetic nanoparticles (MNPs) aligned by the external magnetic field (EMF). It is found that the coercive electric field within the Fe3 O4 MNPs generated by the EMF has a strong and positive influence on the charge generation, which results in a more than 10% increase in free charge carriers. Moreover, the coercive electric field speeds up the charge carrier transport and suppress charge carrier recombination within PSCs. In addition, a shortened extraction time made charge carriers more likely to make it to the electrodes. As a result, more than 15% enhancement in PCE is observed from the PSCs based on the BHJ composite incorporated with the Fe3 O4 MNPs and the EMF as compared with that based on the BHJ composite thin film. Our work indicates that the incorporation of MNPs and the EMF is a facile way to enhance the PCEs of PSCs. This article is protected by copyright. All rights reserved.