Self-powered reduced-dimensionality perovskite photodiodes with controlled crystalline phase and improved stability

Lim, Ju Won,Wang, Huan,Choi, Chi Hun,Kwon, Hannah,Quan, Li Na,Park, Won-Tae,Noh, Yong-Young,Kim, Dong Ha Elsevier 2019 Nano energy Vol.57 No.-

<P><B>Abstract</B></P> <P>In this work, we developed the perovskite photodiodes based on the dimensionality-reduced quasi two-dimensional (Q-2D) photoactive layer structure by incorporating phenylethylammonium iodide (PEAI) into methylammonium lead iodide (MAPbI<SUB>3</SUB>), which effectively enhanced both the crystalline phase and the ambient stability of the perovskite. The Q-2D perovskite photodiode exhibited a dark current of 1.76 × 10<SUP>−7</SUP> A/cm<SUP>2</SUP>, resulting in the detectivity (D*) of 2.20 × 10<SUP>12</SUP> J and responsivity of 0.53 A/W, which is among the highest performance levels without the voltage bias (0 V) due to the systematically optimized perovskite phase resulting in the reduced leakage current. In addition, the current density of Q-2D perovskite photodiode maintained 76% of the initial level current density even after 80 days in the ambient condition, compared to 15% of 3D perovskite photodiode control sample. Such superior performance and stability were mainly attributed to the enhanced degree of crystallization of the Q-2D perovskites, which was confirmed by X-ray diffraction and grazing incidence wide-angle X-ray scattering (GIWAXS) measurement. Also, the improved stability of Q-2D perovskite films was confirmed by both lifetime test and atomic force microscopy studies where the negligible number of pinholes was observed in the quasi-2D perovskite films while considerable deformations were found in the 3D perovskites photodiode. Our study suggests a simple and robust protocol for the development of stable and high-performance perovskite photodetectors via dimensional and constitutional optimization of conventional perovskites for the practical usage of perovskite in the photodiode applications.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The Q-2D perovskite photodiode exhibited the D* of 2.20 × 10<SUP>12</SUP> J and R of 0.53 A/W without the voltage bias (0 V). </LI> <LI> The current density of Q-2D perovskite photodiode maintained 76 % of the initial level while 15 % for the 3D one. </LI> <LI> Grazing incidence wide-angle X-ray scattering (GIWAXS) analysis revealed the origin of the stability improvement. </LI> <LI> Quasi-2D perovskite materials can be promising candidates for stable, tunable and flexible optoelectronic applications. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>Dimensionality-controlled perovskite photodiodes with improved stability were systematically fabricated while retaining the comparable electrical performance of conventional three-dimensional perovskites. The quasi-2D perovskite photodetector exhibited an improved detectivity of 2.20 × 10<SUP>12</SUP> J performance and maintained 76% of initial level while the performance of three-dimensional perovskite photodetector remained only 15% after 80 days. Our study suggests a facile solution for the poor stability of the three-dimensional perovskite, with a potential for the development of highly-stable perovskite optoelectronics.</P> <P>[DISPLAY OMISSION]</P>

Polyethylenimine ethoxylated interlayer-mediated ZnO interfacial engineering for high-performance and low-temperature processed flexible perovskite solar cells: A simple and viable route for one-step processed CH₃NH₃PbI₃

Lim, Ju Won,Wang, Huan,Choi, Chi Hun,Quan, Li Na,Chung, Kyungwha,Park, Won-Tae,Noh, Yong-Young,Kim, Dong Ha Elsevier 2019 Journal of Power Sources Vol.438 No.-

<P><B>Abstract</B></P> <P>Developing perovskite solar cells (PSCs) with high-efficiency and a low-temperature process has great potential for the realization of the scalable, economic, and roll-to-roll based renewable energy conversion devices. ZnO has been recognized as the promising electron transport layer (ETL) that may overcome the limitations of the conventional TiO<SUB>2</SUB>. However, methylammonium lead iodide (MAPbI<SUB>3</SUB>) perovskite is prone to decomposition at the ZnO surface, which hinders the development of simple one-step deposition of perovskite, resulting in the limited photovoltaic performance. Herein, we report interlayer mediated efficient ETLs for viable flexible PSCs. The utilization of polyethyleneimine ethoxylated layer on ZnO prevents the direct contact between the perovskite and ETLs, avoiding the photoactive layer decomposition. Thus, interlayer-mediated PSCs show higher efficiency with enhanced stability by decreasing the electron transport barrier. As a result, the PSC employing tailor-designed ETL interfaces exhibited average power conversion efficiency (PCE) of 15.8%, which was superior by 25.4% to that of a control device (12.6%). With our strategy, we further demonstrated PSCs on flexible substrates which exhibit an average PCE of 11.9% under low-temperature fabrication. The new interface engineering strategy may pave the way to the realization of high performance, easy-to-process, and large-area perovskite optoelectronics.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Universal interface engineering technique for highly stable flexible PSCs. </LI> <LI> The in-depth investigation into the enhanced stability and high-efficiency PSCs. </LI> <LI> Interlayer mediated PSC exhibits 15.8% PCE, superior by 25.4% to control device. </LI> <LI> Low-temperature processed PSCs for the next-generation renewable energy sources. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Analysis and optimization of a typical quasi-zero stiffness vibration isolator

Huan Li,Yang Yu,Jianchun Li,Yancheng Li 국제구조공학회 2021 Smart Structures and Systems, An International Jou Vol.27 No.3

To isolate vibration at a low-frequency range and at the same time to provide sufficient loading support to the isolated structure impose a challenge in vibration isolation. Quasi-zero stiffness (QZS) vibration isolator, as a potential solution to the challenge, has been widely investigated due to its unique property of high-static & low-dynamic stiffness. This paper provides an in-depth analysis and potential optimization of a typical QZS vibration isolator to illustrate the complexity and importance of design optimization. By carefully examining the governing fundamentals of the QZS vibration isolator, a simplified approximation of force and stiffness relationship is derived to enable the characteristic analysis of the QZS vibration isolator. The explicit formulae of the amplitude-frequency response (AFR) and transmissibility of the QZS vibration isolator are obtained by employing the Harmonic Balance Method. The transmissibility curves under force excitation with different values of nonlinear coefficient, damping ratio, and amplitude of excitation are further investigated. As the result, an optimization of the structural parameter has been demonstrated using a comprehensive objective function with considering multiple dynamic characteristic parameters simultaneously. Finally, the genetic algorithm (GA) is adopted to minimise the objective function to obtain the optimal stiffness ratios under different conditions. General recommendations are provided and discussed in the end.

Design and Construction of Polyaniline/Reduced Graphene Oxide Three-Dimensional Dendritic Architecture on Interdigital Electrode for Sensitive Detection Nitrite

Li Li,Huan Liu,Boya Li,Yanan Guo,Liming Qing,Baohui Wang 한국고분자학회 2020 Macromolecular Research Vol.28 No.5

The polyaniline/reduced graphene oxide (PANI/RGO) modified interdigital electrode (IDE) has been successfully fabricated by in situ electrochemical reduction and electrochemical polymerization through cyclic voltammetry. The morphology and topography of PANI/RGO characterized by SEM and AFM display intercrosslinked dendritic structure in three dimensions, and it is favorable for the detection of nitrite due to its large surface area, which can provide the large electrocatalytic active surface and various diffusion paths for nitrite. Herein, the obtained PANI/ RGO/IDE was employed for the electrochemical monitoring platform of nitrite for the first time and the electrochemical performance of the as-developed sensor was investigated via cyclic voltammetry and chronoamperometry. At the optimum conditions, the PANI/RGO/IDE has a linear response in the range from 0.4 to 183.7 mM with a sensitivity of 457.4 μA mM-1 cm-2 and a detection limit of 0.1 μM. Moreover, the obtained PANI/RGO/IDE with excellent long-term stability and reproducibility also can be employed for practical application for the determination of nitrite in tap water, the results show that the recovery rate is desirable. It is expected that IDE can be employed as the substrate electrode decorated with various materials to construct highperformance electrochemical sensors.

Bevacizumab Regulates Cancer Cell Migration by Activation of STAT3

Wu, Huan-Huan,Zhang, Shuai,Bian, Huan,Li, Xiao-Xu,Wang, Lin,Pu, Yin-Fei,Wang, Yi-Xiang,Guo, Chuan-Bin Asian Pacific Journal of Cancer Prevention 2015 Asian Pacific journal of cancer prevention Vol.16 No.15

There are numerous clinical cases indicating that long-term use of bevacizumab may increase the invasiveness of tumors. However, to date, little is known about underlying molecular mechanisms. Therefore, the purpose of our study was to investigate effects of bevacizumab in four cancer cells lines (WSU-HN6, CAL27, Tca83, and HeLa). It was found to promote migration and invasion in the WSU-HN6 and Tca83 cases, while exerting inhibitory effects in CAL27 and HeLa cells. The signal transducer and activator of transcription (STAT) 3 inhibitors niclosamide and S3I-201 inhibited the STAT3 signal pathway, which is activated by bevacizumab. These inhibitors also substantially blocked bevacizumab-induced migration of WSU-HN6 and Tca83 cells. Bevacizumab upregulated interleukin (IL)-6 and phosphorylated (p)-STAT3 expression time-dependently. Therefore, we propose that bevacizumab has differential effects on the migration of different cancer cell lines and promotes migration via the IL-6/STAT3 signaling pathway.

Processing, microstructure and mechanical properties of porous silicon nitride by a slip casting method using petroleum coke as pore former

Huan-Rui Wang,Ji-Qiang Gao,Fang-Li Yu,Yuan Li,Jian-Feng Yang 한양대학교 세라믹연구소 2009 Journal of Ceramic Processing Research Vol.10 No.6

In this study, porous Si3N4 ceramics were obtained by a slip casting method which would be easier applied in industry. The most stable and dispersing aqueous suspension was obtained from a solid slurry content of 56.2%, a carboxymethyl cellulose concentration of 0.3% as the adhesive and 0.05% glycerol as the defoamer. Petroleum coke was used as pore-former, and at the same time, it was helpful for the stability of the suspension. The burning-out of the petroleum coke seemed to be an economical way for increasing the porosity of porous Si3N4. After sintering at 1,800℃ for 2 h, samples with a pore size about 10 μm, porosities of 45-60%, and flexural strength of 52.0-112.1MPa were obtained. In this study, porous Si3N4 ceramics were obtained by a slip casting method which would be easier applied in industry. The most stable and dispersing aqueous suspension was obtained from a solid slurry content of 56.2%, a carboxymethyl cellulose concentration of 0.3% as the adhesive and 0.05% glycerol as the defoamer. Petroleum coke was used as pore-former, and at the same time, it was helpful for the stability of the suspension. The burning-out of the petroleum coke seemed to be an economical way for increasing the porosity of porous Si3N4. After sintering at 1,800℃ for 2 h, samples with a pore size about 10 μm, porosities of 45-60%, and flexural strength of 52.0-112.1MPa were obtained.

Current Status on the Utilization of Osmia Bees as Pollinators of Fruit Trees in China (Hymenoptera: Megachilidae)

Huan-li Xu(徐環李),Long-long Yang(楊龍龍),Yong Jung Kwon(權容正),Eun Yeop Huh(許銀葉) 한국양봉학회 1995 韓國養蜂學會誌 Vol.10 No.2

The Influence of Entrepreneurial Leadership on Team Performance – Focusing on the Mediating Role of Team Efficacy

Huan-Huan Wang,Yan-Nan LI,Jong-Kwan Kim 한국디지털정책학회 2020 디지털융복합연구 Vol.18 No.10

Functional Connections of the Vestibulo-spino-adrenal Axis in the Control of Blood Pressure Via the Vestibulosympathetic Reflex in Conscious Rats

Huan-Jun Lu,Mei-Han Li,Mei-Zhi Li,박상언,김민선,Yuan-Zhe Jin,박병림 대한약리학회 2015 The Korean Journal of Physiology & Pharmacology Vol.19 No.5

Significant evidence supports the role of the vestibular system in the regulation of blood pressure during postural movements. In the present study, the role of the vestibulo-spino-adrenal (VSA) axis in the modulation of blood pressure via the vestibulosympathetic reflex was clarified by immunohistochemical and enzyme immunoassay methods in conscious rats with sinoaortic denervation. Expression of c-Fos protein in the intermediolateral cell column of the middle thoracic spinal regions and blood epinephrine levels were investigated, following microinjection of glutamate receptor agonists or antagonists into the medial vestibular nucleus (MVN) and/or sodium nitroprusside (SNP)-induced hypotension. Both microinjection of glutamate receptor agonists (NMDA and AMPA) into the MVN or rostral ventrolateral medullary nucleus (RVLM) and SNP-induced hypotension led to increased number of c-Fos positive neurons in the intermediolateral cell column of the middle thoracic spinal regions and increased blood epinephrine levels. Pretreatment with microinjection of glutamate receptor antagonists (MK-801 and CNQX) into the MVN or RVLM prevented the increased number of c-Fos positive neurons resulting from SNP-induced hypotension, and reversed the increased blood epinephrine levels. These results indicate that the VSA axis may be a key component of the pathway used by the vestibulosympathetic reflex to maintain blood pressure during postural movements.

Flame Retardancy of Epoxy Resin Improved by Graphene Hybrid Containing Phosphorous, Boron, Nitrogen and Silicon Elements

Li Li,Huan Wang,Fenglin Hua,Mingming Wang,Yuanshuo Zhang,Hui Xi,Jing Yang,Zhiwang Yang,Ziqiang Lei 한국고분자학회 2021 Macromolecular Research Vol.29 No.9

An effective ternary organic-inorganic composite flame retardant of reduced graphene oxide-poly-dopamine@graphitic carbon nitride@10-(2,5-dihydroxyphenyl)- 10-H-9-oxa-10-phosphaphenanthrene-10-oxide (RGO-PDA@g-C3N4@ODOPB) was successfully fabricated by co-precipitation method. Its property concerning the intrinsic flame retardancy and the mechanical performance was well studied when it was used as co-additives in combination with ammonium polyphosphate (APP) in epoxy resin (EP) samples. The surface morphology and the structure of RGO-PDA@g-C3N4 @ODOPB were characterized by SEM, and the molecular structure and compositions were investigated by FT-IR, powder XRD and 1H NMR. TGA, limit oxygen index (LOI), vertical burning test (UL-94), cone calorimeter test, and SEM were also used to investigate the thermal properties and flame retardancy of materials. As expected, the flame retardancy of EP was significantly heightened after adding of RGOPDA@ g-C3N4@ODOPB composites. It showed that with the 20% adding of RGO-PDA@g-C3N4@ODOPB/APP into EP led to the decreasing of the peak heat release rate and the total heat release at 78% and 62.5%, respectively. Meanwhile, the LOI value of the EP composites was as high as 29% and reached UL-94 V-0 rate. It was deemed that the excellent flame retardancy was attributed to the forming of compact and stable carbon layer, which was being catalytic carbonization by APP existed in the RGO-PDA@g-C3N4@ODOPB/APP composites. At the same time, the non-combustible gas released from thermal cracking of g-C3N4 during the combustion also benefited the flame retardant performance of EP.