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>

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>

Soft-template-carbonization route to highly textured mesoporous carbon–TiO₂ inverse opals for efficient photocatalytic and photoelectrochemical applications

Quan, Li Na,Jang, Yoon Hee,Stoerzinger, Kelsey A.,May, Kevin J.,Jang, Yu Jin,Kochuveedu, Saji Thomas,Shao-Horn, Yang,Kim, Dong Ha The Royal Society of Chemistry 2014 Physical chemistry chemical physics Vol.16 No.19

<P>Hierarchically organized mesoporous carbon–TiO<SUB>2</SUB> inverse opal nanostructures were synthesized by complementary colloid and block copolymer (BCP) self-assembly, where the triblock copolymer P123 acts simultaneously as the template and the carbon source. Highly ordered mesoporous inverse opal nanostructures with a nano-textured surface morphology and multiple-length scale nanopores provide increased light-activated surface area and scattering effects, leading to enhanced photoabsorption efficiency and the transport of matter. UV-vis absorption, X-ray photoelectron spectroscopy and Mott–Schottky measurement studies show that incorporation of carbon moieties into TiO<SUB>2</SUB><I>via</I> direct conversion of BCPs creates a new energy level above the valence band of TiO<SUB>2</SUB>, resulting in an effective decrease in the band gap. A significantly enhanced visible light photocatalytic activity was demonstrated for the mesoporous carbon–TiO<SUB>2</SUB> inverse opals in terms of the degradation of <I>p</I>-nitrophenol (∼79%) and photoelectrochemical water splitting (∼0.087%).</P> <P>Graphic Abstract</P><P>A significantly enhanced visible light photocatalytic activity was demonstrated for highly ordered mesoporous carbon–TiO<SUB>2</SUB> inverse opal nanostructures. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c4cp00803k'> </P>

Tailoring the Energy Landscape in Quasi-2D Halide Perovskites Enables Efficient Green-Light Emission

Quan, Li Na,Zhao, Yongbiao,Garcí,a de Arquer, F. Pelayo,Sabatini, Randy,Walters, Grant,Voznyy, Oleksandr,Comin, Riccardo,Li, Yiying,Fan, James Z.,Tan, Hairen,Pan, Jun,Yuan, Mingjian,Bakr, Osman American Chemical Society 2017 NANO LETTERS Vol.17 No.6

<P>Organo-metal halide perovskites are a promising platform for optoelectronic applications in view of their excellent charge-transport and bandgap tunability. However, their low photoluminescence quantum efficiencies, especially in low-excitation regimes, limit their efficiency for light emission. Consequently, perovskite light-emitting devices are operated under high injection, a regime under which the materials have so far been unstable. Here we show that, by concentrating photoexcited states into a small subpopulation of radiative domains, one can achieve a high quantum yield, even at low excitation intensities. We tailor the composition of quasi-2D perovskites to direct the energy transfer into the lowest-bandgap minority phase and to do so faster than it is lost to nonradiative centers. The new material exhibits 60% photoluminescence quantum yield at excitation intensities as low as 1.8 mW/cm(2), yielding a ratio of quantum yield to excitation intensity of 0.3 cm(2)/mW; this represents a decrease of 2 orders of magnitude in the excitation power required to reach high efficiency compared with the best prior reports. Using this strategy, we report light-emitting diodes with external quantum efficiencies of 7.4% and a high luminescence of 8400 cd/m(2).</P>

Hybrid hierarchical nanostructures for alternative electrodes in dye-sensitized solar cells

( Li Na Quan ),장윤희,장유진,김지현,김동하 한국공업화학회 2015 한국공업화학회 연구논문 초록집 Vol.2015 No.1

The electrode in dye-sensitized solar cells (DSSCs) demands high porosity and surface area so that the sensitizers can be sufficiently adsorbed and the paths for electron transport can be electronically interconnected. Highly ordered hierarchical mesoporous TiO₂ networks can provide fast electron transport paths, and ordered mesopores can enhance light scattering, facilitate infiltration of the electrolyte, and ultimately increase the power conversion efficiency. In this work, we investigated the formation of hierarchical mesoporous TiO₂ and carbon-TiO₂ nanostructures and their application as photoanode in DSSCs. Those structures were fabricated by using polystyrene beads for SiO2 inverse opal template, and infiltration of a common solution consisting of amphiphilic triblock copolymer (P123) and TiO₂ sol-gel precursors. A commercially available triblock copolymer Pluronic P123 played key role in the generation of nanovoids within the hierarchical mesoporous TiO₂ opal and also as a carbon source. Mesoporous carbon-TiO₂ opal is fabricated via sequential UV-stabilization and calcination of P123 containing TiO₂ precursors and their performance as electrode was compared with carbon-free analogues. The changes in photovoltaic performances were monitored by controlling the loaded amount of mesoporous TiO₂ opals and carbon-TiO₂ opals. It was observed that the incorporation of mesoporous carbon-TiO₂ opals into the conventional photoanode of DSSCs can enhance the charge transport and collection that lead to enhanced photovoltaic performance by ~25.78 %.

Evalluation of Bilolgy Technology Innovarion Risks Based on Anallytical Hierarchy Process and Fuzzy Mathematics

QUAN Cong-na,LI Jian-min,LI Bo 인하대학교 정석물류통상연구원 2009 인하대학교 정석물류통상연구원 학술대회 Vol.2009 No.10

Biology technology innovation an important way of improving the competition ability of enterprises and promoting the sustainable development of enterprises, and the success of biology technology innovation can provide a great deal of benefit for them. However, high risks exist during the course of technology innovation, thus rate of sucess is low and the enterprise may suffer great loss from the risks. So it is a key problem of biology technology innovation how to cvaluate exactly the risk of technology innovation, but ambiguity of risk itself and people’s cognition cause more difficulties of risk evaluation. In this paper, the analytical hierarchy process and fuzzy mathematics theory are applied to the evaluation of th biology technology innovation risks, which makes the evaluation from qualitative analysis to quantitative analysis, reduces the impact of the subjective factors and improves the accuracy of risk evaluation.

Mesoporous Carbon-TiO₂Beads with Nanotextured Surfaces as Photoanodes in Dye-Sensitized Solar Cells

Quan, Li Na,Jang, Yoon Hee,Jang, Yu Jin,Kim, Jihyeon,Lee, Wonmok,Moon, Jun Hyuk,Kim, Dong Ha Wiley (John WileySons) 2014 CHEM SUS CHEM Vol.7 No.9

<P>Mesoporous TiO2 and carbon-TiO2 beads with highly roughened surfaces at the nanoscale were prepared by using triblock copolymer P123 simultaneously as template and carbon source in combination with colloid self-assembly. In addition, their role as modifier of the photoanode in the efficiency enhancement of dye-sensitized solar cells is discussed. Hierarchically organized TiO2 networks can provide fast electron transport paths, and ordered mesopores can enhance light scattering as well as facilitate infiltration of the electrolyte. It was found that there is an optimum loading level of mesoporous TiO2 and carbon-TiO2 beads, that is, 1.0 and 0.5?wt%, with respect to the control P25 TiO2 nanoparticles, respectively, for maximizing the photovoltaic performance. An increase in the photovoltaic performance by up to 21.45% was achieved by incorporation of mesoporous carbon-TiO2 beads into the conventional photoanode of DSSCs owing to enhanced charge transport and collection effects.</P>

Soft-template-carbonization route to highly textured mesoporous carbon-TiO₂ inverse opals for efficient photocatalytic and photoelectrochemical applications

장윤희 ( Li Na Quan ),장유진,사지토마스,김동하 한국공업화학회 2015 한국공업화학회 연구논문 초록집 Vol.2015 No.1

TiO₂ has been recognized as representative metal oxide semiconductor material with excellent photocatalytic activity due to its good stability, nontoxicity, and UV absorbance. However, the lack of visible light activity has been a critical issue due to the relatively large band gap. In this work, hierarchically organized mesoporous carbon-TiO₂ inverse opal nanostructures were synthesized by complementary colloid and block copolymer (BCP) self-assembly, where the triblock copolymer P123 acts simultaneously as template and carbon source. Highly ordered mesoporous inverse opal nanostructures with nano-textured surface morphology and multiple-length scale nanopores provide increased light-activated surface area and scattering effects, leading to enhanced photoabsorption efficiency and the transport of matters. UV-vis absorption and X-ray photoelectron spectroscopy studies show that incorporation of carbon moieties into TiO₂ via direct conversion of BCPs creates a new energy level above the valence band of TiO₂, resulting in an effective decrease in the band gap. A significant enhanced visible light photocatalytic activity was demonstrated for the mesoporous carbon- TiO₂ inverse opals in terms of the degradation of p-nitrophenol and photoelectrochemical water splitting.

Clinical Study of Tumor Angiogenesis and Perfusion Imaging Using Multi-slice Spiral Computed Tomography for Breast Cancer

Xu, Na,Lei, Zhen,Li, Xiao-Long,Zhang, Jun,Li, Chen,Feng, Guo-Quan,Li, Di-Nuo,Liu, Jing-Yi,Wei, Qiang,Bian, Ting-Ting,Zou, Tian-Yu Asian Pacific Journal of Cancer Prevention 2013 Asian Pacific journal of cancer prevention Vol.14 No.1

Objectives: To explore the correlation between multi-slice spiral CT (MSCT) perfusion parameters and the expression of vascular endothelial growth factor (VEGF) as well as matrix metalloproteinase-2 (MMP-2) in breast cancer. Methods: Forty five breast cancer patients and 16 patients with benign breast tumor, both confirmed by pathology examination, were enrolled. All underwent MSCT perfusion imaging to obtain perfusion maps and data for parameters including blood flow (BF), blood volume (BV) and permeability surface (PS). Cancer patients did not receive treatment prior to surgery. The expression of VEGF and MMP-2 were examined with both immunohistochemistry and Western blotting. Results: The levels of VEGF and MMP-2 by immunohistochemistry were significantly higher in the breast cancer group (P < 0.01) than the benign tumor group. Relative OD values from Western blotting were also higher in cancer cases (P < 0.05). Similarly, the mean MSCT perfusion parameters (BF, BV, PS) were significantly higher in the breast cancer group (P < 0.01), BF and BV positively correlating with VEGF expression (r = 0.878 and 0.809 respectively, P < 0.01); PS and VEGF and MMP-2 expression were also positively correlated (r= 0.860, 0.786 respectively, P < 0.01). Conclusion: There is a correlation between breast cancer MSCT perfusion parameters and VEGF andMMP-2 expression, which might be useful for detection of breast lesions, qualitative diagnosis of breast cancer, and evaluation of breast cancer treatment.

ACOX1 destabilizes p73 to suppress intrinsic apoptosis pathway and regulates sensitivity to doxorubicin in lymphoma cells

( Fei-meng Zheng ),( Wang-bing Chen ),( Tao Qin ),( Li-na Lv ),( Bi Feng ),( Yan-ling Lu ),( Zuo-quan Li ),( Xiao-chao Wang ),( Li-ju Tao ),( Hong-wen Li ),( Shu-you Li ) 생화학분자생물학회(구 한국생화학분자생물학회) 2019 BMB Reports Vol.52 No.9

Lymphoma is one of the most curable types of cancer. However, drug resistance is the main challenge faced in lymphoma treatment. Peroxisomal acyl-CoA oxidase 1 (ACOX1) is the rate-limiting enzyme in fatty acid β-oxidation. Deregulation of ACOX1 has been linked to peroxisomal disorders and carcinogenesis in the liver. Currently, there is no information about the function of ACOX1 in lymphoma. In this study, we found that upregulation of ACOX1 promoted proliferation in lymphoma cells, while downregulation of ACOX1 inhibited proliferation and induced apoptosis. Additionally, overexpression of ACOX1 increased resistance to doxorubicin, while suppression of ACOX1 expression markedly potentiated doxorubicin-induced apoptosis. Interestingly, downregulation of ACOX1 promoted mitochondrial location of Bad, reduced mitochondrial membrane potential and provoked apoptosis by activating caspase-9 and caspase-3 related apoptotic pathway. Overexpression of ACOX1 alleviated doxorubicin-induced activation of caspase-9 and caspase-3 and decrease of mitochondrial membrane potential. Importantly, downregulation of ACOX1 increased p73, but not p53, expression. p73 expression was critical for apoptosis induction induced by ACOX1 downregulation. Also, overexpression of ACOX1 significantly reduced stability of p73 protein thereby reducing p73 expression. Thus, our study indicated that suppression of ACOX1 could be a novel and effective approach for treatment of lymphoma. [BMB Reports 2019; 52(9): 566-571]