Transparent-flexible-multimodal triboelectric nanogenerators for mechanical energy harvesting and self-powered sensor applications

Zhou, Qitao,Park, Jun Gyu,Kim, Kyeong Nam,Thokchom, Ashish Kumar,Bae, Juyeol,Baik, Jeong Min,Kim, Taesung Elsevier 2018 Nano energy Vol.48 No.-

<P><B>Abstract</B></P> <P>Triboelectric nanogenerators (TENGs) harvest and convert mechanical energy to electrical energy. TENGs that are transparent and flexible can be applied to various (opto-)electronic devices supporting finger- or pen-based touchscreen inputs. This paper presents a transparent, flexible TENG that harvests mechanical tapping energy (typically discarded) by simple placement on touchscreen devices. The developed TENG consists of flexible and transparent conducting electrodes (FTCE) with high transmittance (> 93%) and low sheet resistance (18.5 Ω/sq), and transparent 3D-hierarchical polydimethylsiloxane (PDMS) with porous pyramid-patterns. In this study, the developed TENG directly powered eight light-emitting diodes (LEDs) by harvesting the mechanical energy produced by tapping with a touch pen while playing a smartphone game. We also used the transparent TENG as a transparent single-electrode-based, self-powered raindrop detection sensor on a window for a smart home. Our results indicate that the proposed TENG can be used not only as an effective mechanical energy harvester for transparent, flexible, and next-generation optoelectronics devices but also as a self-powered sensor for future Internet-of-Things applications.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Flexible transparent conducting electrodes (FTCEs) are fabricated by an inkjet printer. </LI> <LI> A PDMS interlayer with 3D micro/-nanostructures is prepared by particle lithography. </LI> <LI> A transparent and flexible TENG is fabricated by the FTCEs and PDMS interlayers. </LI> <LI> The TENG harvests the mechanical energy produced when tapping electronic devices. </LI> <LI> The TENG works as single-electrode-based self-powered raindrop sensors. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

구리 전기도금 방법을 이용한 은 나노와이어 투명전극의 전기전도도 향상

지한나,장지성,이상엽,정중희,Ji, Hanna,Jang, Jiseong,Lee, Sangyeob,Chung, Choong-Heui 한국재료학회 2019 한국재료학회지 Vol.29 No.5

Transparent conducting electrodes are essential components in various optoelectrical devices. Although indium tin oxide thin films have been widely used for transparent conducting electrodes, silver nanowire network is a promising alternative to indium tin oxide thin films owing to its lower processing cost and greater suitability for flexible device application. In order to widen the application of silver nanowire network, the electrical conductance has to be improved while maintaining high optical transparency. In this study, we report the enhancement of the electrical conductance of silver nanowire network transparent electrodes by copper electrodeposition on the silver nanowire networks. The electrodeposited copper lowered the sheet resistance of the silver nanowire networks from $21.9{\Omega}{\square}$ to $12.6{\Omega}{\square}$. We perform detailed X-ray diffraction analysis revealing the effect of the amount of electrodeposited copper-shell on the sheet resistance of the core-shell(silver/copper) nanowire network transparent electrodes. From the relationship between the cross-sectional area of the copper-shell and the sheet resistance of the transparent electrodes, we deduce the electrical resistivity of electrodeposited copper to be approximately 4.5 times that of copper bulk.

Highly transparent and conductive oxide-metal-oxide electrodes optimized at the percolation thickness of AgO_x for transparent silicon thin-film solar cells

Jo, Hyunjin,Yang, Jo-Hwa,Choi, Soo-Won,Park, Jaeho,Song, Eun Jin,Shin, Myunhun,Ahn, Ji-Hoon,Kwon, Jung-Dae Elsevier 2019 Solar energy materials and solar cells Vol.202 No.-

<P><B>Abstract</B></P> <P>Highly transparent and conductive oxide-metal-oxide (OMO) electrodes comprising aluminum-doped zinc-oxide (AZO) and ultrathin Ag or oxygen (O<SUB>2</SUB>)-doped Ag (AgO<SUB>x</SUB>) metal layers were fabricated for use in thin-film silicon solar cells. The surface morphologies of the metal layers and the transparencies and conductivities of OMO electrodes were investigated near the percolation thickness values of the metal layers. The percolation metal thickness, which means the metal layer is morphologically continuous, could be used to optimize the transparent OMO electrode. Additionally, thin Ag-based OMO (AgO<SUB>x</SUB> OMO) with superior performance could be fabricated by adding O<SUB>2</SUB>. The optimized AgO<SUB>x</SUB> OMO electrodes yielded the highest average transmittance (<I>T</I> <SUB>avg</SUB>) of 93.5% and the lowest average optical loss (OL<SUB>avg</SUB>) of 1.01% within 500–800 nm at the percolation thickness of ~6 nm, thus, maintaining low conductivity. These outcomes were superior to the responses of the percolated Ag OMO (<I>T</I> <SUB>avg</SUB> = 87.2%; OL<SUB>avg</SUB> = 1.01%). Using the OMO structure at the rear electrode, transparent hydrogenated amorphous silicon thin-film solar was fabricated for building integrated photovoltaic windows. The best figure-of-merit (FOM; equal to the product of <I>T</I> <SUB>avg</SUB> and efficiency <I>η</I>) values of the OMO-based transparent solar cells could be obtained for percolated OMO structures. The cells using AgO<SUB>x</SUB> OMO (AgO<SUB>x</SUB> cells) performed better than the Ag cells; the best FOMs of AgO<SUB>x</SUB> and Ag cells were 140.8 (<I>T</I> <SUB>avg</SUB> = 27.8%; <I>η</I> = 5.51%) and 104.6% (<I>T</I> <SUB>avg</SUB> = 18.9%; <I>η</I> = 5.54%), respectively. These results could contribute to the development of high-performance transparent solar cells or optoelectronic devices.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Transparent/conductive oxide-metal-oxide (OMO) electrodes were fabricated. </LI> <LI> Oxygen doping effects in thin Ag film is investigated. </LI> <LI> Optimization of OMO electrodes was based on the percolation metal thickness. </LI> <LI> Thin oxygen-doped Ag-based OMO electrodes yielded better performances. </LI> <LI> Optimized electrodes can be used in high-performance transparent solar cells/devices. </LI> </UL> </P>

Effects of the Ag Layer Embedded in NIZO Layers as Transparent Conducting Electrodes for Liquid Crystal Displays

오병윤,Gi-Seok Heo 한국전기전자재료학회 2016 Transactions on Electrical and Electronic Material Vol.17 No.1

In the present work, a Ni-doped indium zinc oxide (NIZO) film and its multilayers with Ag layers were investigated as transparent conducting electrodes for liquid crystal display (LCD) applications, as a substitute for indium tin oxide (ITO) electrodes. By interposing the Ag layer between the NIZO layers, the loss of the optical transmittance occurred; however, the Ag layer brought enhancement of electrical sheet resistance to the NIZO/Ag/NIZO multilayer electrode. The twisted nematic cell based on the NIZO/Ag/NIZO multilayer electrode exhibited superior electro-optical characteristics than those based on single NIZO electrode and was competitive compared to those based on the conventional ITO electrode. An LCD-based NIZO/Ag/NIZO multilayer electrode may allow new approaches to conventional ITO electrodes in display technology.

Effects of the Ag Layer Embedded in NIZO Layers as Transparent Conducting Electrodes for Liquid Crystal Displays

Oh, Byeong-Yun,Heo, Gi-Seok The Korean Institute of Electrical and Electronic 2016 Transactions on Electrical and Electronic Material Vol.17 No.1

In the present work, a Ni-doped indium zinc oxide (NIZO) film and its multilayers with Ag layers were investigated as transparent conducting electrodes for liquid crystal display (LCD) applications, as a substitute for indium tin oxide (ITO) electrodes. By interposing the Ag layer between the NIZO layers, the loss of the optical transmittance occurred; however, the Ag layer brought enhancement of electrical sheet resistance to the NIZO/Ag/NIZO multilayer electrode. The twisted nematic cell based on the NIZO/Ag/NIZO multilayer electrode exhibited superior electro-optical characteristics than those based on single NIZO electrode and was competitive compared to those based on the conventional ITO electrode. An LCD-based NIZO/Ag/NIZO multilayer electrode may allow new approaches to conventional ITO electrodes in display technology.

Fabrication of highly conductive PEDOT:PSS film by purification and its applications as transparent electrode for organic solar cell

김소연,이승환,김세열,정문현,김정훈,김중현 한국공업화학회 2014 한국공업화학회 연구논문 초록집 Vol.2014 No.1

Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)(PEDOT:PSS), a conducting polymer showing high conductivity and transparency, is regarded as a promising material for optoelectronic devices because it enables cost-effective and flexible devices as well as roll-to-roll mass production. However, pristine PEDOT:PSS yields a conductivity much too low to be used as an electrode. In this work, we demonstrated that purification to PEDOT:PSS solutions reduces thickness significantly. The insulating PSS component on the PEDOT:PSS dispersion can be removed by purification. Finally, we obtained high conductivity of PEDOT:PSS films up to 2000 S/cm Which is comparable to that of ITO. We also employed the optimized PEDOT:PSS films treated by purification as transparent anodes for ITO-free Organic photovoltaic cells fabricated on flexible substrates.

Transparent bifacial a-Si:H solar cells employing silver oxide embedded transparent rear electrodes for improved transparency

Jo, Hyunjin,Yang, Jo-Hwa,Lee, Ji-hoon,Lim, Jung-Wook,Lee, Jaesung,Shin, Myunhun,Ahn, Ji-Hoon,Kwon, Jung-Dae Elsevier 2018 SOLAR ENERGY -PHOENIX ARIZONA THEN NEW YORK- Vol.170 No.-

<P><B>Abstract</B></P> <P>We developed a transparent oxide–metal–oxide (OMO) structure using aluminum-doped zinc oxide and oxidized silver (AgO<SUB>x</SUB>) as a transparent electrode of a hydrogenated amorphous silicon (a-Si:H) thin-film solar cell for use in building-integrated photovoltaic (BIPV) windows. The oxygen (O<SUB>2</SUB>) addition (O<SUB>2</SUB> flow rate) was optimized for a metal-to-dielectric intermediate-phase AgO<SUB>x</SUB> OMO to have high transparency and high conductivity, which were confirmed by finite-difference time-domain simulation. Using the AgO<SUB>x</SUB> OMO as a rear electrode, transparent a-Si:H solar cells were fabricated for BIPV window application. The performance of the fabricated cells showed highest bifacial efficiency (b-<I>η</I>) of 7.87% at AgO<SUB>x</SUB> OMO of 1 sccm, and highest average transmittance (<I>T</I> <SUB>500–800</SUB>, i.e., wavelength range: 500–800 nm) of 21.9% at AgO<SUB>x</SUB> OMO of 3 sccm, i.e., improvements from b-<I>η</I> = 7.42% and <I>T</I> <SUB>500–800</SUB> = 18.8% at Ag OMO of 0 sccm. The cell with the optimized AgO<SUB>x</SUB> OMO (3 sccm) achieved b-<I>η</I> = 7.69% and the best figure of merit (product of b-<I>η</I> and <I>T</I> <SUB>500–800</SUB>) of 169%, i.e., 30% higher than the Ag OMO cell (139%). The developed AgO<SUB>x</SUB> OMO electrodes could be used in BIPV windows or in other optical devices requiring both high transparency and high conductivity.</P> <P><B>Highlights</B></P> <P> <UL> <LI> AgO<SUB>x</SUB> is introduced in a transparent oxide-metal-oxide (OMO) structure. </LI> <LI> Oxidization of AgO<SUB>x</SUB> is optimized for high transparency and efficiency of transparent a-Si:H solar cells. </LI> <LI> Optical property of AgO<SUB>x</SUB>-OMO is investigated experimentally and theoretically. </LI> <LI> Bifacial operation property of a-Si:H solar cells was presented. </LI> </UL> </P>

Review on the Synthesis and Antioxidation of Cu Nanowires for Transparent Conductive Electrodes

Jia Feng Chao,Yong Qiang Meng,Jingbing Liu,Qian Qian Zhang,Hao Wang 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2019 NANO Vol.14 No.4

Transparent conducting films based on solution-synthesized copper nanowires (Cu NWs) are considered to be an attractive alternative to indium tin oxide (ITO) due to the relative abundance of Cu and the low cost of solution-phase NW coating processes. Moreover, transparent electrodes tend to be flexible. This makes Cu NWs more attractive because ITO is brittle and can not meet the requirements of flexibility. For Cu NWs, aspect ratio is an important property. Cu NWs can be directly prepared by chemical reduction with various reducing agents and suitable capping agents. In general, the selectivity of the capping agent is very important for the formation of one-dimensional nanostructures because it plays a major role in the thermodynamic regulations and growth kinetics that influence the geometry and morphology of the crystal facets. Therefore, different aspect ratios are formed. Conductivity is the most important property for transparent electrodes. Organic pickling, annealing and glare pulses have a certain improvement in conductivity. Meanwhile, it is also essential to increase the oxidation resistance of the transparent electrode. The reduction of graphene oxide (r-GO), the coating of metal and polymer improve the oxidation resistance of the transparent electrode to varying degrees. This paper reviews the effect of different capping agents on the aspect ratio of NWs, and the effects of different post-treatments on oxidation resistance and conductivity of transparent electrodes.

Fabrication of a transparent conducting electrode based on graphene/silver nanowires via layer-by-layer method for organic photovoltaic devices

Tugba Camic, B.,Oytun, Faruk,Hasan Aslan, M.,Jeong Shin, Hee,Choi, Hyosung,Basarir, Fevzihan Academic Press 2017 Journal of Colloid and Interface Science Vol. No.

<P><B>Abstract</B></P> <P>A solution-processed transparent conducting electrode was fabricated via layer-by-layer (LBL) deposition of graphene oxide (GO) and silver nanowires (Ag NWs). First, graphite was oxidized with a modified Hummer’s method to obtain negatively-charged GO sheets, and Ag NWs were functionalized with cysteamine hydrochloride to acquire positively-charged silver nanowires. Oppositely-charged GO and Ag NWs were then sequentially coated on a 3-aminopropyltriethoxysilane modified glass substrate via LBL deposition, which provided highly controllable thin films in terms of optical transmittance and sheet resistance. Next, the reduction of GO sheets was performed to improve the electrical conductivity of the multilayer films. The resulting GO/Ag NWs multilayer was characterized by a UV–Vis spectrometer, field emission scanning electron microscope (FE-SEM), optical microscope (OM) and sheet resistance using a four-point probe method. The best result was achieved with a 2-bilayer film, resulting in a sheet resistance of 6.5Ω sq<SUP>−1</SUP> with an optical transmittance of 78.2% at 550nm, which values are comparable to those of commercial ITO electrodes. The device based on a 2-bilayer hybrid film exhibited the highest device efficiency of 1.30% among the devices with different number of graphene/Ag NW LBL depositions.</P> <P><B>Graphical abstract</B></P> <P>Highly transparent and conductive graphene/Ag NWs hybrid electrode has been successfully developed by using layer-by-layer method for organic photovoltaic cells as an alternative to conventional indium tin oxide electrode.</P> <P>[DISPLAY OMISSION]</P>

전도성 고분자의 전기전도도 향상 연구 및 이를 이용한 투명전극 응용

임소은 ( Soeun Im ),김소연 ( Soyeon Kim ),김세열 ( Seyul Kim ),김선주 ( Felix Sunjoo Kim ),김중현 ( Jung Hyun Kim ) 한국공업화학회 2015 공업화학 Vol.26 No.6

투명 전극의 응용분야가 확대되고 시장의 규모가 커짐에 따라 기존 투명 전극 재료인 ITO (Indium Tin Oxide)를 대체할 차세대 투명전극의 개발에 관심이 집중되고 있다. 다양한 후보군 중에서도 대표적인 전도성 고분자인 PEDOT : PSS [poly(3,4-ethylenedioxythiophene) : poly(styrene sulfonate)]는 기계적 유연성을 갖고 있으면서도 소재와 공정 상의가격 경쟁력이 크기 때문에 미래 소자 구현을 위한 투명전극 재료로 주목을 받고 있으며, 현재 PEDOT : PSS의 전기전도도 수준을 ITO나 금속의 수준으로 향상시키기 위해 다양한 화학적/물리적 처리를 통한 기능성 향상에 많은 연구가진행 중이다. 본 총설에서는 전도성 고분자의 전기 전도도를 향상시키기 위한 다양한 공정 기술에 대한 연구 현황을짚어보고자 한다. 대표적으로 유기용매, 이온성 액체, 계면활성제 등과 같은 첨가제와 박막에 대한 산 처리 공정, 물리적 인장을 통한 전기전도도 향상 연구를 들 수 있다. 또한 이러한 공정을 적용하여 전도성 고분자 투명 전극을 전자및 에너지 소자에 응용한 사례도 간략히 소개하고자 한다. As the need for next-generation flexible electronics grows, novel materials and technologies that can replace conventional indium tin oxide (ITO) for transparent electrodes have been of great interest. Among them, a conducting polymer, especially poly(3,4-ethylenedioxythiophene) : poly(styrene sulfonate) (PEDOT : PSS) is one of the most promising candidates because it is mechanically flexible, inexpensive, and capable of being processed in solution. Currently, there are a lot of research efforts on enhancing its electrical conductivity to the level of ITO or metal electrodes through chemical and/or physical processing. In this review article, we present various additives and pre-/post-deposition processing methods for improving the electrical conductivity of PEDOT : PSS. Some of representative reports are also introduced, which demonstrated the use of conductivity-enhanced PEDOT : PSS as transparent electrodes in electronics and energy conversion.