Showing papers by "Xiong Gong published in 2018"

Genistein: A Dual Inhibitor of Both Amyloid β and Human Islet Amylin Peptides

Abstract: Abnormal misfolding and aggregation of amyloid peptides into amyloid fibrils are common and critical pathological events in many neurodegenerative diseases. Most inhibitors or drugs have been developed to prevent amyloid aggregation of a specific peptide, showing sequence-dependent inhibition mechanisms. It is more challenging to develop or discover inhibitors capable of preventing the aggregation of two or more different amyloid peptides. Genistein, a major phytoestrogen in soybean, has been widely used as an anti-inflammation and cerebrovascular drug due to its antioxidation and antiacetylcholinesterase effects. Herein, we examine the inhibitory effects of genistein on the aggregation of amyloid-β (Aβ, associated with Alzheimer’s disease) and human islet amylin (hIAPP, associated with type 2 diabetes) and Aβ- and hIAPP-induced neurotoxicity using a combination of experimental and computational approaches. Collective experimental results from thioflavin T (ThT), atomic force microscopy (AFM), and circula...

Solution-processed broadband polymer photodetectors with a spectral response of up to 2.5 μm by a low bandgap donor–acceptor conjugated copolymer

Abstract: Photodetectors (PDs) with infrared (IR) response have extensive industrial and scientific applications. Broadband polymer PDs that operate at room temperature have drawn the greatest attention in the past years. In this study, solution-processed polymer PDs with a spectral response ranging from 350 nm to 2500 nm are reported. The low bandgap donor–acceptor (D–A) conjugated copolymer contributes to the IR photo-response. Implementation of a bulk heterojunction device structure with polypyrrole as an interfacial layer to match the energy level of the low bandgap D–A conjugated copolymer and the Ba/Al bi-cathode to compress dark current gave rise to a large photocurrent to dark current ratio, which resulted in detectivities greater than 1011 Jones (1 Jones = 1 cm Hz1/2 W−1) at wavelengths ranging from 350 nm to 2500 nm. Thus, our finding of utilization of bulk heterojunction composite consisting of a D–A low bandgap polymer blended with a fullerene derivative provides a facile way to detect IR radiation, indicating that broadband polymer PDs are promising for photoelectronic technology in the future.

Room-Temperature-Operated Ultrasensitive Broadband Photodetectors by Perovskite Incorporated with Conjugated Polymer and Single-Wall Carbon Nanotubes

Abstract: In this work, room-temperature-operated ultrasensitive solution-processed perovskite photodetectors (PDs) with near infrared (NIR) photoresponse are reported. In order to enable perovskite PDs possessing extended NIR photoresponse, novel n-type low bandgap conjugated polymer, poly[(N,N′-bis(2-octyldodecyl)-1,4,5,8-naphthalene diimide-2,6-diyl) (2,5-dioctyl-3,6-di(thiophen-2-yl)pyrrolo[3,4-c]pyrrole-1,4-dione-5,5′-diyl)] (NDI-DPP), which has strong absorption in the NIR region, is developed and then employed in perovskite PDs. By the formation of type II band alignment between NDI-DPP with single-wall carbon nanotubes (SWCNTs), the NIR absorption of NDI-DPP is exploited, which contributes to the NIR photoresponse for the perovskite PDs, where perovskite is incorporated with NDI-DPP and SWCNTs as well. In addition, SWCNTs incorporated with perovskite active layer can offer the percolation pathways for high charge-carrier mobility, which tremendously boosts the charge transfer in the photoactive layer, and consequently improves the photocurrent in the visible region. As a result, the perovskite PDs exhibit the responsivities of ≈400 and ≈150 mA W−1 and the detectivities of over 6 × 1012 Jones (1 Jones = 1 cm Hz1/2 W−1) and over 2 × 1012 Jones in the visible and NIR regions, respectively. This work reports the development of perovskite PDs with NIR photoresponse, which is terrifically beneficial for the practical applications of perovskite PDs.

Cesium-Doped Vanadium Oxide as the Hole Extraction Layer for Efficient Perovskite Solar Cells.

Abstract: In this study, we report the utilization of low-temperature solution-processed Cs-doped VOX thin films as the hole extraction layers (HELs) in perovskite solar cells (PSCs). It is found that the VOX:yCs (where y is the mole ratio of Cs versus V and y = 0.1, 0.3, and 0.5) thin films possess better electrical conductivities than that of the pristine VOX thin film. As a result, the PSCs incorporated with the VOX:yCs HEL exhibit large fill factors and high short-circuit currents, with consequently high power conversion efficiencies, which is more than 30% enhancement as compared with pristine VOX HEL. Our studies provide a facial way to enhance the electrical conductivity of the hole extraction layer for boosting device performance of perovskite solar cells.

Enhanced thermoelectric properties of two-dimensional conjugated polymers

Abstract: Organic thermoelectric materials have drawn great attention in the past years. In this study, we report the thermoelectric properties of ferric salt bis(trifluoromethane)sulfonimide (TFSI−) doped two-dimensional (2D) conjugated polymer, poly[[4,8-bis[(5-ethylhexyl)thienyl]benzo[1,2-b;3,3-b]dithiophene-2,6-diyl][3-fluoro-2-[(2-ethylhexyl)carbonyl]thieno[3,4-b]thiophenediyl]] (PTB7-DT). It is found that the electrical conductivities of TFSI− doped 2D PTB7-DT are nearly 100 times larger than those of TFSI− doped one-dimensional (1D) corresponding conjugate polymer, poly[[4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b′]dithiophene-2,6-diyl][3-fluoro-2-[(2-ethylhexyl)carbonyl]thieno[3,4-b]thiophenediyl]] (PTB7) at the same doping levels. Moreover, TFSI− doped 2D PTB7-DT possess over 20 times larger power factor (79.8 μW/mK2) than that of TFSI− doped 1D PTB7. The enhancement of electrical conductivities of TFSI− doped 2D PTB7-DT is attributed to enhanced charge carrier densities and polaron densities. The studies of grazing incidence wide angle X-ray scattering further indicate that the π-π stacking distances of TFSI− doped 2D PTB7-DT along the in-plane direction are largely reduced compared to that of TFSI− doped 1D PTB7, which would facilitate the inter-chain and the intra-chain charge carrier transport, resulting in enhanced electrical conductivities. All these results demonstrate that 2D conjugated polymers are promising candidate materials for approaching high performance organic thermoelectric electronics.

Ultrasensitive Perovskite Photodetectors by Co Partially Substituted Hybrid Perovskite

Abstract: In the past nine years, hybrid perovskite materials have attracted extensive research interests in both academic and industrial sectors. In this work, we report ultrasensitive solution-processed pe...

Efficient Perovskite Solar Cells with Reduced Photocurrent Hysteresis through Tuned Crystallinity of Hybrid Perovskite Thin Films.

Abstract: Hybrid perovskite materials used for realization of efficient perovskite solar cells have drawn great attention in both academic and industrial sectors. It was reported that the crystallinity of hybrid thin-film perovskite materials plays an important role in device performance. In this study, we report a novel and simple method to tune the crystallinity of CH3NH3PbI3 thin film for device performance of perovskite solar cells. By employing tetraphenylphosphonium chloride on the top of PbI2 thin layer in the two-step perovskite deposition processes, the crystallinity of the resultant CH3NH3PbI3 thin film was tuned. As a result, perovskite solar cells by the CH3NH3PbI3 thin film with tuned crystallinity exhibit an enlarged open-circuit voltage and enhanced short-circuit current, thus boosted efficiency as well as reduced photocurrent hysteresis compared to pristine CH3NH3PbI3 thin film. These results indicate that our study provides a new simple way to boost device performance of perovskite solar cells thro...