Mohamed El Kabbash, T. Letsou, M. Hinczewski, G. Strangi, Chunlei Guo
Perfect light absorption (PLA) in nanophotonics has a wide range of applications from solar-thermal based applications to radiative cooling. However, most of the proposed platforms require intense lithography which makes them of minor practical relevance. On the other hand, thin-film light absorbers are lithographically free and can be deposited cheaply on large area based on matured technologies. However, thin-film light absorbers were thought to have major limitation and cannot be tailored compared to metamaterials. Here, we show how to design PLA using thin-films in terms of wavelength range, bandwidth, spatial profile of optical losses, directionality and iridescence. We also show that iridescent free, PLA can occur by simply heating metallic thin-films when the metal is of low reflectance and its oxide is of high refractive index. We theoretically and experimentally demonstrate Generalized Brewster angle effect in thin film light absorbers. In addition, we demonstrate hydrogen sensing using three different PLA strategies showing record sensitivity and figure of merit. Furthermore, we show various strategies to create ultra-pure structural colors. Finally, we demonstrate different solar-thermal applications for novel thin-film PLA designs.
{"title":"Designer thin-film based perfect light absorption and its applications in structural coloring, gas sensing, and solar-thermal conversion (Conference Presentation)","authors":"Mohamed El Kabbash, T. Letsou, M. Hinczewski, G. Strangi, Chunlei Guo","doi":"10.1117/12.2528370","DOIUrl":"https://doi.org/10.1117/12.2528370","url":null,"abstract":"Perfect light absorption (PLA) in nanophotonics has a wide range of applications from solar-thermal based applications to radiative cooling. However, most of the proposed platforms require intense lithography which makes them of minor practical relevance. On the other hand, thin-film light absorbers are lithographically free and can be deposited cheaply on large area based on matured technologies. However, thin-film light absorbers were thought to have major limitation and cannot be tailored compared to metamaterials. Here, we show how to design PLA using thin-films in terms of wavelength range, bandwidth, spatial profile of optical losses, directionality and iridescence. We also show that iridescent free, PLA can occur by simply heating metallic thin-films when the metal is of low reflectance and its oxide is of high refractive index. We theoretically and experimentally demonstrate Generalized Brewster angle effect in thin film light absorbers. In addition, we demonstrate hydrogen sensing using three different PLA strategies showing record sensitivity and figure of merit. Furthermore, we show various strategies to create ultra-pure structural colors. Finally, we demonstrate different solar-thermal applications for novel thin-film PLA designs.","PeriodicalId":331787,"journal":{"name":"Nanoengineering: Fabrication, Properties, Optics, Thin Films, and Devices XVI","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2019-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127925245","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Flexible piezoelectric nanogenerator based on sonochemically synthesized ZnO nanoflakes for self‐powered devices and wearable energy harvesting (Conference Presentation)","authors":"F. Alam, S. Aghaei, A. Jalal, N. Pala","doi":"10.1117/12.2531751","DOIUrl":"https://doi.org/10.1117/12.2531751","url":null,"abstract":"","PeriodicalId":331787,"journal":{"name":"Nanoengineering: Fabrication, Properties, Optics, Thin Films, and Devices XVI","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2019-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121711039","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Syazwani Mohd Noor, Hansol Jang, Kyungnae Baek, Yi-Rong Pei, Al-Mahmnur Alam, J. Choy, J. Hyun
Disordered photonic systems as observed in iridescent insects and flowers introduces new pathways for realizing cost-effective and scalable structural colors. In this work, we present a fast-colorimetric humidity sensor derived from a disordered arrangement of polydisperse nanoporous titania microspheres. The sensor relies on changes in the total scattering of the microspheres upon variations in the surrounding humidity. The incoherent scattering from each particle allows the sum of the individual cross sections to determine the total scattering cross section, which converts the individual noisy spectra to a smoothly varying spectrum that gives rise to a saturated color.[1] We show that because the titania microspheres is highly porous with 1~2 nm-sized nanopores, water can diffuse into the particle interior via intracrystalline dynamics, thereby changing the effective permittivity and consequently the scattered color at ultra-fast speeds (sub 50ms). Our results provide a practical route toward achieving cheap, simple, scalable, ultrafast colorimetric humidity sensors using structural colors from disordered nanoporous microspheres [2]. [1] Alam, A-M; Baek K; Son J; Pei Y-R; Kim D-H; Choy J-H; and Hyun J-K. Generating Color from Polydisperse, Near Micron-Sized TiO2 Particles, ACS Appl. Mater. Interfaces, 2017, 9 (28), 23941– 23948 [2] M-Noor, S; Jang, H ; Baek K; Pei Y-R; Alam, A-M; Kim,Y.H; Kim, I.S; Choy, J.H and Hyun J-K. Ultrafast humidity-responsive structural colors from disordered nanoporous titania microspheres. Submitted (2019)
{"title":"Colorimetric humidity sensors with sub-50ms response times using randomly arranged titania microspheres\u0000 (Conference Presentation)","authors":"Syazwani Mohd Noor, Hansol Jang, Kyungnae Baek, Yi-Rong Pei, Al-Mahmnur Alam, J. Choy, J. Hyun","doi":"10.1117/12.2528696","DOIUrl":"https://doi.org/10.1117/12.2528696","url":null,"abstract":"Disordered photonic systems as observed in iridescent insects and flowers introduces new pathways for realizing cost-effective and scalable structural colors. In this work, we present a fast-colorimetric humidity sensor derived from a disordered arrangement of polydisperse nanoporous titania microspheres. The sensor relies on changes in the total scattering of the microspheres upon variations in the surrounding humidity. The incoherent scattering from each particle allows the sum of the individual cross sections to determine the total scattering cross section, which converts the individual noisy spectra to a smoothly varying spectrum that gives rise to a saturated color.[1] We show that because the titania microspheres is highly porous with 1~2 nm-sized nanopores, water can diffuse into the particle interior via intracrystalline dynamics, thereby changing the effective permittivity and consequently the scattered color at ultra-fast speeds (sub 50ms). Our results provide a practical route toward achieving cheap, simple, scalable, ultrafast colorimetric humidity sensors using structural colors from disordered nanoporous microspheres [2].\u0000 \u0000\u0000[1] Alam, A-M; Baek K; Son J; Pei Y-R; Kim D-H; Choy J-H; and Hyun J-K. Generating Color from Polydisperse, Near Micron-Sized TiO2 Particles, ACS Appl. Mater. Interfaces, 2017, 9 (28), 23941– 23948\u0000[2] M-Noor, S; Jang, H ; Baek K; Pei Y-R; Alam, A-M; Kim,Y.H; Kim, I.S; Choy, J.H and Hyun J-K. Ultrafast humidity-responsive structural colors from disordered nanoporous titania microspheres. Submitted (2019)","PeriodicalId":331787,"journal":{"name":"Nanoengineering: Fabrication, Properties, Optics, Thin Films, and Devices XVI","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2019-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128438897","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Soyeong Kwon, M. Kwon, Jungeun Song, Eunah Kim, B. Kim, Sangwook Lee, Dong-Wook Kim
The coupling between surface plasmons (SPs) and excitons in 2D transition metal dichalcogenide (TMD) materials has been attracted growing research attention in recent days. Strong electric field confinement and absorption enhancement could be expected, as a result of the SP-excition couping. We prepared exfoliated flakes of MoS2, a representative TMD material, on Au nanogratings fabricated by electron beam lithography. We studied influences of propagating SP on optical properties of the MoS2 flakes on the Au nanogratings, based on both experimental measurements and numerical calculations. Local surface potential maps of the samples suggested that the strain states in the MoS2 flakes and the dipoles formed at the MoS2/ Au interface could cause spatial modulation of the bandgap energies of the MoS2 flakes. The surface potential measurements were carried out using Kelvin probe force microscopy in dark and under TM/TE-mode light illumination. Band diagrams of the MoS2/Au nanogratings were proposed to explain all the experimental results. This study can help us to understand and control the physical characteristics of the TMD/metal nanostructures.
{"title":"Fabrication and characterizations of MoS2 layers on Au nanogratings (Conference Presentation)","authors":"Soyeong Kwon, M. Kwon, Jungeun Song, Eunah Kim, B. Kim, Sangwook Lee, Dong-Wook Kim","doi":"10.1117/12.2528603","DOIUrl":"https://doi.org/10.1117/12.2528603","url":null,"abstract":"The coupling between surface plasmons (SPs) and excitons in 2D transition metal dichalcogenide (TMD) materials has been attracted growing research attention in recent days. Strong electric field confinement and absorption enhancement could be expected, as a result of the SP-excition couping. We prepared exfoliated flakes of MoS2, a representative TMD material, on Au nanogratings fabricated by electron beam lithography. We studied influences of propagating SP on optical properties of the MoS2 flakes on the Au nanogratings, based on both experimental measurements and numerical calculations. Local surface potential maps of the samples suggested that the strain states in the MoS2 flakes and the dipoles formed at the MoS2/ Au interface could cause spatial modulation of the bandgap energies of the MoS2 flakes. The surface potential measurements were carried out using Kelvin probe force microscopy in dark and under TM/TE-mode light illumination. Band diagrams of the MoS2/Au nanogratings were proposed to explain all the experimental results. This study can help us to understand and control the physical characteristics of the TMD/metal nanostructures.","PeriodicalId":331787,"journal":{"name":"Nanoengineering: Fabrication, Properties, Optics, Thin Films, and Devices XVI","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2019-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133283694","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
L. Johnson, Huajun Xu, Y. D. Coene, D. Elder, K. Clays, L. Dalton, B. Robinson
Recent developments in hybrid electro-optic (EO) systems, in which an organic material with an ultra-large second-order susceptibility is combined with silicon (SOH) or gold (POH) waveguides at the nanoscale. Tight confinement of the optical and RF fields in such devices has enabled operating frequencies > 300 GHz and voltage-length parameters (UπL) < 40 V-μm with existing high-performance organic electro-optic (OEO) materials. However, achieving UπL values on the order of 1 V-μm will require a new generation of OEO materials. The short path lengths within hybrid devices greatly alleviate concerns about optical loss, enabling development of OEO chromophores with extraordinarily large hyperpolarizabilities and refractive indices at telecom wavelengths. However, as device dimensions shrink, chromophore-surface interactions, space-efficiency, and refractive index anisotropy become more critical. Practical device implementations also require materials with high thermal and chemical stability and uncompromising EO performance. We have used a theory-aided design process applying classical and quantum mechanical techniques to design a new generation of OEO materials intended to meet the needs of hybrid devices. We have synthesized these materials, characterized their hyperpolarizability by hyper-Rayleigh scattering, and evaluated their bulk electro-optic behavior and prospects for implementation in nanoscale devices.
{"title":"Next-generation materials for hybrid electro-optic systems (Conference Presentation)","authors":"L. Johnson, Huajun Xu, Y. D. Coene, D. Elder, K. Clays, L. Dalton, B. Robinson","doi":"10.1117/12.2530719","DOIUrl":"https://doi.org/10.1117/12.2530719","url":null,"abstract":"Recent developments in hybrid electro-optic (EO) systems, in which an organic material with an ultra-large second-order susceptibility is combined with silicon (SOH) or gold (POH) waveguides at the nanoscale. Tight confinement of the optical and RF fields in such devices has enabled operating frequencies > 300 GHz and voltage-length parameters (UπL) < 40 V-μm with existing high-performance organic electro-optic (OEO) materials. However, achieving UπL values on the order of 1 V-μm will require a new generation of OEO materials. The short path lengths within hybrid devices greatly alleviate concerns about optical loss, enabling development of OEO chromophores with extraordinarily large hyperpolarizabilities and refractive indices at telecom wavelengths. However, as device dimensions shrink, chromophore-surface interactions, space-efficiency, and refractive index anisotropy become more critical. Practical device implementations also require materials with high thermal and chemical stability and uncompromising EO performance. We have used a theory-aided design process applying classical and quantum mechanical techniques to design a new generation of OEO materials intended to meet the needs of hybrid devices. We have synthesized these materials, characterized their hyperpolarizability by hyper-Rayleigh scattering, and evaluated their bulk electro-optic behavior and prospects for implementation in nanoscale devices.","PeriodicalId":331787,"journal":{"name":"Nanoengineering: Fabrication, Properties, Optics, Thin Films, and Devices XVI","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2019-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129518641","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Ordered nanostructured crystals of thin perovskites films are of great interest to researchers because of the dimensional-dependence of their photoelectronic properties for developing the perovskites with novel properties. In this presentation, both top-down and bottom-up approaches for fabricating nanostructured perovskite films are demonstrated. First, a variety of micro/nanopatterns of a perovskite film are fabricated by either microimprinting or transfer-printing a thin spin-coated precursor film in soft-gel state with a topographically pre-patterned polymer mold, followed by thermal treatment for complete conversion of the precursor film to a perovskite one. Second, we also demonstrate a simple and robust route, involving the controlled crystallization of the perovskites templated with a self-assembled block copolymer (BCP), for fabricating nanopatterned perovskite films with various shapes and nanodomain sizes. When the precursor ion solution of a perovskite and poly(styrene)-block-poly(2-vinylpyridine) (PS-b-P2VP) was spin-coated on the substrate, a nanostructured BCP was developed by microphase separation. Spontaneous crystallization of the precursor ions preferentially coordinated with the P2VP domains yielded ordered nanocrystals with various nanostructures. The nanopatterned perovskites showed significantly enhanced photoluminescence (PL) with high resistance to both humidity and heat due to geometrically confining crystals in and passivation with the P2VP chains. The self-assembled perovskite films with high PL performance provided a facile control of color coordinates by color conversion layers in blue-emitting devices for cool-white emission.
{"title":"Thin nanostructured perovskite films for high performance photo-electronic applications (Conference Presentation)","authors":"Cheolmin Park","doi":"10.1117/12.2531353","DOIUrl":"https://doi.org/10.1117/12.2531353","url":null,"abstract":"Ordered nanostructured crystals of thin perovskites films are of great interest to researchers because of the dimensional-dependence of their photoelectronic properties for developing the perovskites with novel properties. In this presentation, both top-down and bottom-up approaches for fabricating nanostructured perovskite films are demonstrated. First, a variety of micro/nanopatterns of a perovskite film are fabricated by either microimprinting or transfer-printing a thin spin-coated precursor film in soft-gel state with a topographically pre-patterned polymer mold, followed by thermal treatment for complete conversion of the precursor film to a perovskite one. Second, we also demonstrate a simple and robust route, involving the controlled crystallization of the perovskites templated with a self-assembled block copolymer (BCP), for fabricating nanopatterned perovskite films with various shapes and nanodomain sizes. When the precursor ion solution of a perovskite and poly(styrene)-block-poly(2-vinylpyridine) (PS-b-P2VP) was spin-coated on the substrate, a nanostructured BCP was developed by microphase separation. Spontaneous crystallization of the precursor ions preferentially coordinated with the P2VP domains yielded ordered nanocrystals with various nanostructures. The nanopatterned perovskites showed significantly enhanced photoluminescence (PL) with high resistance to both humidity and heat due to geometrically confining crystals in and passivation with the P2VP chains. The self-assembled perovskite films with high PL performance provided a facile control of color coordinates by color conversion layers in blue-emitting devices for cool-white emission.","PeriodicalId":331787,"journal":{"name":"Nanoengineering: Fabrication, Properties, Optics, Thin Films, and Devices XVI","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2019-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130295174","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Xu Zhang, J. Grajal, J. Vazquez-Roy, U. Radhakrishna, Xiaoxue Wang, W. Chern, Lin Zhou, Yuhao Zhang, Han Wang, M. Dubey, J. Kong, M. Dresselhaus, T. Palacios
MoS2 has attracted substantial attention due to its atomic thickness and outstanding electronic and mechanical properties. As one of the thinnest semiconductors in the world, MoS2 is promising to build flexible electronics that can be integrated with objects with arbitrary shapes and inspires a vision of distributed ubiquitous electronics. Despite recent advances in two-dimensional materials-based electronics (e.g. 2D materials-based transistors, memory devices and sensors), an efficient and flexible energy harvesting solution is necessary, but still missing, to enable a self-powered system. At the same time, the electromagnetic (EM) radiation in the Wi-Fi band (2.4 GHz and 5.9 GHz) is becoming increasingly ubiquitous and it would be beneficial to be able to wirelessly harvest it to power future distributed electronics. However, the rectennas (i.e. RF energy harvesters) based on flexible semiconductors have not been fast enough to cover the Wi-Fi band due to their limited transport properties. Here we present a unique MoS2 semiconducting-metallic phase heterojunction, which enables a flexible and high-speed Schottky diode with a cutoff frequency of 10 GHz. Due to a novel lateral architecture and self-aligned phase engineering, our MoS2 Schottky diode exhibits significantly reduced parasitic capacitance and series resistance. By integrating the MoS2 rectifier with a flexible Wi-Fi band antenna, we successfully fabricate a fully flexible rectenna that demonstrates direct energy harvesting of EM radiation in the Wi-Fi band with zero external bias (battery-free). Moreover, taking advantage of the nonlinearity of the MoS2 Schottky diode, a frequency mixing in the gigahertz range is also successfully demonstrated on flexible substrates.
{"title":"Two-dimensional MoS2-enabled flexible rectenna for wireless energy harvesting in the Wi-Fi band (Conference Presentation)","authors":"Xu Zhang, J. Grajal, J. Vazquez-Roy, U. Radhakrishna, Xiaoxue Wang, W. Chern, Lin Zhou, Yuhao Zhang, Han Wang, M. Dubey, J. Kong, M. Dresselhaus, T. Palacios","doi":"10.1117/12.2530059","DOIUrl":"https://doi.org/10.1117/12.2530059","url":null,"abstract":"MoS2 has attracted substantial attention due to its atomic thickness and outstanding electronic and mechanical properties. As one of the thinnest semiconductors in the world, MoS2 is promising to build flexible electronics that can be integrated with objects with arbitrary shapes and inspires a vision of distributed ubiquitous electronics. Despite recent advances in two-dimensional materials-based electronics (e.g. 2D materials-based transistors, memory devices and sensors), an efficient and flexible energy harvesting solution is necessary, but still missing, to enable a self-powered system. At the same time, the electromagnetic (EM) radiation in the Wi-Fi band (2.4 GHz and 5.9 GHz) is becoming increasingly ubiquitous and it would be beneficial to be able to wirelessly harvest it to power future distributed electronics. However, the rectennas (i.e. RF energy harvesters) based on flexible semiconductors have not been fast enough to cover the Wi-Fi band due to their limited transport properties. Here we present a unique MoS2 semiconducting-metallic phase heterojunction, which enables a flexible and high-speed Schottky diode with a cutoff frequency of 10 GHz. Due to a novel lateral architecture and self-aligned phase engineering, our MoS2 Schottky diode exhibits significantly reduced parasitic capacitance and series resistance. By integrating the MoS2 rectifier with a flexible Wi-Fi band antenna, we successfully fabricate a fully flexible rectenna that demonstrates direct energy harvesting of EM radiation in the Wi-Fi band with zero external bias (battery-free). Moreover, taking advantage of the nonlinearity of the MoS2 Schottky diode, a frequency mixing in the gigahertz range is also successfully demonstrated on flexible substrates.","PeriodicalId":331787,"journal":{"name":"Nanoengineering: Fabrication, Properties, Optics, Thin Films, and Devices XVI","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2019-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129048326","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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