{"id":70071,"date":"2024-09-04T09:31:35","date_gmt":"2024-09-04T07:31:35","guid":{"rendered":"https:\/\/www.iemn.fr\/?p=70071"},"modified":"2024-09-12T16:14:19","modified_gmt":"2024-09-12T14:14:19","slug":"innovative-molecular-junctions-for-terahertz-switches-and-detectors","status":"publish","type":"post","link":"https:\/\/www.iemn.fr\/en\/newsletter\/innovative-molecular-junctions-for-terahertz-switches-and-detectors.html","title":{"rendered":"Innovative Molecular Junctions for Terahertz Switches and Detectors"},"content":{"rendered":"<div  class='flex_column av-1jvmr33-1fb0113428302a1a7987f98770c97c20 av_one_full  avia-builder-el-0  el_before_av_hr  avia-builder-el-first  first flex_column_div'     ><style type=\"text\/css\" data-created_by=\"avia_inline_auto\" id=\"style-css-av-m0zd8oeo-ed6cd9c3dad4e81e6d7709b9cdfd5004\">\n#top .av_textblock_section.av-m0zd8oeo-ed6cd9c3dad4e81e6d7709b9cdfd5004 .avia_textblock{\nfont-size:24px;\n}\n<\/style>\n<section  class='av_textblock_section av-m0zd8oeo-ed6cd9c3dad4e81e6d7709b9cdfd5004'   itemscope=\"itemscope\" itemtype=\"https:\/\/schema.org\/BlogPosting\" itemprop=\"blogPost\" ><div class='avia_textblock'  itemprop=\"text\" ><p style=\"text-align: center;\"><span style=\"color: #c46500;\">Innovative Molecular Junctions for Terahertz Switches and Detectors<\/span><\/p>\n<\/div><\/section><\/div>\n<style type=\"text\/css\" data-created_by=\"avia_inline_auto\" id=\"style-css-av-lyydekit-0abbee231ff3a63bb08d21586e81d83b\">\n#top .hr.av-lyydekit-0abbee231ff3a63bb08d21586e81d83b{\nmargin-top:30px;\nmargin-bottom:30px;\n}\n.hr.av-lyydekit-0abbee231ff3a63bb08d21586e81d83b .hr-inner{\nwidth:200;\nmax-width:45%;\n}\n<\/style>\n<div  class='hr av-lyydekit-0abbee231ff3a63bb08d21586e81d83b hr-custom  avia-builder-el-2  el_after_av_one_full  el_before_av_one_half  hr-center hr-icon-yes'><span class='hr-inner inner-border-av-border-fat'><span class=\"hr-inner-style\"><\/span><\/span><span class='av-seperator-icon' aria-hidden='true' data-av_icon='\ue808' data-av_iconfont='entypo-fontello'><\/span><span class='hr-inner inner-border-av-border-fat'><span class=\"hr-inner-style\"><\/span><\/span><\/div><\/p>\n<div  class='flex_column av-mfufnb-9c5c917c4f4169e44ff1d4faad8f918f av_one_half  avia-builder-el-3  el_after_av_hr  el_before_av_one_half  first flex_column_div'     ><section  class='av_textblock_section av-m0zd3bqp-c46e16de19596c30fe2c0d7c0f92307d'   itemscope=\"itemscope\" itemtype=\"https:\/\/schema.org\/BlogPosting\" itemprop=\"blogPost\" ><div class='avia_textblock'  itemprop=\"text\" ><div class=\"introduction\">\n<div class=\"clearfix text-formatted field field--name-body field--type-text-with-summary field--label-hidden field__item\">\n<div class=\"tex2jax_process\">\n<blockquote>\n<p style=\"text-align: left;\">The Nanostructures, nano-Components and Molecules (NCM) group, in collaboration with the Linear Conjugate Systems (SCL) group at Moltech-Anjou (Angers) and the New Materials Chemistry Laboratory (U. Mons, Belgium), has developed molecular junctions designed to function as switches in the terahertz (THz) frequency range, a significant advance in molecular-scale electronics.<\/p>\n<\/blockquote>\n<h5>\n<style type=\"text\/css\" data-created_by=\"avia_inline_auto\" id=\"style-css-av-qawvnx-10-faac08b8af764b0e51e072935fcdfc3b\">\n.av_font_icon.av-qawvnx-10-faac08b8af764b0e51e072935fcdfc3b{\ncolor:#7bb0e7;\nborder-color:#7bb0e7;\n}\n.av_font_icon.av-qawvnx-10-faac08b8af764b0e51e072935fcdfc3b .av-icon-char{\nfont-size:22px;\nline-height:22px;\n}\n<\/style>\n<span  class='av_font_icon av-qawvnx-10-faac08b8af764b0e51e072935fcdfc3b avia_animate_when_visible av-icon-style- avia-icon-pos-left avia-icon-animate'><span class='av-icon-char' aria-hidden='true' data-av_icon='\ue889' data-av_iconfont='entypo-fontello' ><\/span><\/span><\/h5>\n<p>These molecular junctions consist of self-assembled monolayers (SAMs) of molecules with a \u03c0-\u03c3-\u03c0 structure. This structure comprises two conjugated (\u03c0) moieties linked by a non-conjugated (\u03c3) spacer, a configuration that allows the device to exhibit negative differential conductance (NDC) - a phenomenon in which an increase in voltage across a device results in a decrease in current.<\/p>\n<h5>\n<style type=\"text\/css\" data-created_by=\"avia_inline_auto\" id=\"style-css-av-qawvnx-7-457f3db7d0e0bdd8099fb9c4a87a9c74\">\n.av_font_icon.av-qawvnx-7-457f3db7d0e0bdd8099fb9c4a87a9c74{\ncolor:#7bb0e7;\nborder-color:#7bb0e7;\n}\n.av_font_icon.av-qawvnx-7-457f3db7d0e0bdd8099fb9c4a87a9c74 .av-icon-char{\nfont-size:22px;\nline-height:22px;\n}\n<\/style>\n<span  class='av_font_icon av-qawvnx-7-457f3db7d0e0bdd8099fb9c4a87a9c74 avia_animate_when_visible av-icon-style- avia-icon-pos-left avia-icon-animate'><span class='av-icon-char' aria-hidden='true' data-av_icon='\ue889' data-av_iconfont='entypo-fontello' ><\/span><\/span><\/h5>\n<p>NDC occurs when the applied electrical voltage aligns the energy levels of the two conjugated subunits, generating a current peak, followed by a decrease as these levels become misaligned. This property is essential for the operation of molecular switches, playing a crucial role in the transition between high- and low-conductance states under the influence of terahertz irradiation.<\/p>\n<h5>\n<style type=\"text\/css\" data-created_by=\"avia_inline_auto\" id=\"style-css-av-qawvnx-6-7a1f1154f4ca687090f1bca48a3f102b\">\n.av_font_icon.av-qawvnx-6-7a1f1154f4ca687090f1bca48a3f102b{\ncolor:#7bb0e7;\nborder-color:#7bb0e7;\n}\n.av_font_icon.av-qawvnx-6-7a1f1154f4ca687090f1bca48a3f102b .av-icon-char{\nfont-size:22px;\nline-height:22px;\n}\n<\/style>\n<span  class='av_font_icon av-qawvnx-6-7a1f1154f4ca687090f1bca48a3f102b avia_animate_when_visible av-icon-style- avia-icon-pos-left avia-icon-animate'><span class='av-icon-char' aria-hidden='true' data-av_icon='\ue889' data-av_iconfont='entypo-fontello' ><\/span><\/span><\/h5>\n<p>The experimental set-up involved creating molecular junctions by carefully assembling SAMs on ultra-flat gold electrodes, then measuring their electronic transport properties using conductive atomic force microscopy (C-AFM) (Figure 1.a). This technique, combined with terahertz laser irradiation (at 30THz and 2.5THz), enabled the switching behaviour to be observed and analysed in real time and at room temperature (Figure 1.b). It was found that at 30 THz, the NDC effect could be completely and reversibly suppressed as a function of terahertz wave power and frequency, which is not only a major experimental achievement but also a validation of theoretical predictions (figure 1.c). This behaviour indicates a highly sensitive interaction between molecular junctions and the terahertz field, underlining the potential of these junctions for use in advanced terahertz detectors.<\/p>\n<\/div>\n<\/div>\n<\/div>\n<\/div><\/section><\/div>\n<div  class='flex_column av-429ettj-a257fb27f08aa208d735f7722a07916f av_one_half  avia-builder-el-8  el_after_av_one_half  el_before_av_one_full  flex_column_div'     ><section  class='av_textblock_section av-m0zd5jhj-b81c22922debac2928dee8a4ada58558'   itemscope=\"itemscope\" itemtype=\"https:\/\/schema.org\/BlogPosting\" itemprop=\"blogPost\" ><div class='avia_textblock'  itemprop=\"text\" ><div class=\"introduction\">\n<div class=\"clearfix text-formatted field field--name-body field--type-text-with-summary field--label-hidden field__item\">\n<div class=\"tex2jax_process\">\n<p><span style=\"font-weight: 600;\">\n<style type=\"text\/css\" data-created_by=\"avia_inline_auto\" id=\"style-css-av-3jhf9kn-53950eba7b38f50c64cc160caeb82f96\">\n.av_font_icon.av-3jhf9kn-53950eba7b38f50c64cc160caeb82f96{\ncolor:#7bb0e7;\nborder-color:#7bb0e7;\n}\n.av_font_icon.av-3jhf9kn-53950eba7b38f50c64cc160caeb82f96 .av-icon-char{\nfont-size:22px;\nline-height:22px;\n}\n<\/style>\n<span  class='av_font_icon av-3jhf9kn-53950eba7b38f50c64cc160caeb82f96 avia_animate_when_visible av-icon-style- avia-icon-pos-left avia-icon-animate'><span class='av-icon-char' aria-hidden='true' data-av_icon='\ue889' data-av_iconfont='entypo-fontello' ><\/span><\/span><\/span>The mechanism for suppressing NDC effects under terahertz irradiation is based on a dynamic interaction between the THz wave and the molecular orbitals of the two subunits of the molecular system. This interaction induces a resonant charge transfer between the energy levels of the molecules, leading to a reduction in the current at the conductance peaks. In addition, the suppression effect is enhanced by a phenomenon known as 'coherent tunneling destruction', where terahertz irradiation temporarily disables the passage of electrons across the molecular junction, thereby reducing the overall conductance. The presence of surface plasmon polaritons, interacting with the molecular levels, also contributes to this suppression.<\/p>\n<\/div>\n<\/div>\n<\/div>\n<div class=\"section-elements\">\n<h5>\n<style type=\"text\/css\" data-created_by=\"avia_inline_auto\" id=\"style-css-av-2xtykdz-86eb5660e24930a73e1d5bad1a3a0d61\">\n.av_font_icon.av-2xtykdz-86eb5660e24930a73e1d5bad1a3a0d61{\ncolor:#7bb0e7;\nborder-color:#7bb0e7;\n}\n.av_font_icon.av-2xtykdz-86eb5660e24930a73e1d5bad1a3a0d61 .av-icon-char{\nfont-size:22px;\nline-height:22px;\n}\n<\/style>\n<span  class='av_font_icon av-2xtykdz-86eb5660e24930a73e1d5bad1a3a0d61 avia_animate_when_visible av-icon-style- avia-icon-pos-left avia-icon-animate'><span class='av-icon-char' aria-hidden='true' data-av_icon='\ue889' data-av_iconfont='entypo-fontello' ><\/span><\/span><\/h5>\n<p>However, when the devices were irradiated at 2.5 THz, suppression of the NDC behaviour was not observed. This indicates that the photon energy of 2.5 THz (around 10 meV) is insufficient to induce the same suppression effect as that observed at 30 THz. These results highlight the importance of the terahertz irradiation frequency in the operation of the molecular switch, demonstrating that the response of the device is strongly dependent on the incident photon energy.<\/p>\n<h5>\n<style type=\"text\/css\" data-created_by=\"avia_inline_auto\" id=\"style-css-av-2mwnm5z-acabdd03cb91e18b32fc61c6628941cd\">\n.av_font_icon.av-2mwnm5z-acabdd03cb91e18b32fc61c6628941cd{\ncolor:#7bb0e7;\nborder-color:#7bb0e7;\n}\n.av_font_icon.av-2mwnm5z-acabdd03cb91e18b32fc61c6628941cd .av-icon-char{\nfont-size:22px;\nline-height:22px;\n}\n<\/style>\n<span  class='av_font_icon av-2mwnm5z-acabdd03cb91e18b32fc61c6628941cd avia_animate_when_visible av-icon-style- avia-icon-pos-left avia-icon-animate'><span class='av-icon-char' aria-hidden='true' data-av_icon='\ue889' data-av_iconfont='entypo-fontello' ><\/span><\/span><\/h5>\n<p>Looking to the future, the integration of these molecular switches into practical terahertz detectors seems possible. The team proposes to use transparent electrodes with a large surface area, such as monolayer graphene, which would be almost transparent to terahertz waves, thus facilitating the detection process. In addition, the nature of the molecules, which can be optimised by chemical engineering, would allow the frequency response of these devices to be tuned by modifying the conjugated \u03c0 groups, thus extending their applicability across a range of terahertz frequencies.<\/p>\n<\/div>\n<div class=\"tex2jax_process\"><\/div>\n<\/div><\/section><\/div>\n<div  class='flex_column av-25duuqf-57047cda88393b1942c5ec9c46039e9a av_one_full  avia-builder-el-13  el_after_av_one_half  avia-builder-el-last  first flex_column_div  column-top-margin'     ><section  class='av_textblock_section av-m0zd62sg-65cd401dc4472bb4ca5ca54e6b7500f3'   itemscope=\"itemscope\" itemtype=\"https:\/\/schema.org\/BlogPosting\" itemprop=\"blogPost\" ><div class='avia_textblock'  itemprop=\"text\" ><div class=\"introduction\">\n<div class=\"clearfix text-formatted field field--name-body field--type-text-with-summary field--label-hidden field__item\">\n<div class=\"tex2jax_process\"><\/div>\n<\/div>\n<\/div>\n<div class=\"tex2jax_process\"><\/div>\n<p><a href=\"https:\/\/www.iemn.fr\/wp-content\/uploads\/2024\/09\/visuelImen.png\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-70421 aligncenter\" src=\"https:\/\/www.iemn.fr\/wp-content\/uploads\/2024\/09\/visuelImen.png\" alt=\"\" width=\"700\" height=\"382\" srcset=\"https:\/\/www.iemn.fr\/wp-content\/uploads\/2024\/09\/visuelImen.png 900w, https:\/\/www.iemn.fr\/wp-content\/uploads\/2024\/09\/visuelImen-300x164.png 300w, https:\/\/www.iemn.fr\/wp-content\/uploads\/2024\/09\/visuelImen-768x419.png 768w, https:\/\/www.iemn.fr\/wp-content\/uploads\/2024\/09\/visuelImen-18x10.png 18w, https:\/\/www.iemn.fr\/wp-content\/uploads\/2024\/09\/visuelImen-705x385.png 705w\" sizes=\"auto, (max-width: 700px) 100vw, 700px\" \/><\/a><\/p>\n<h5>\n<style type=\"text\/css\" data-created_by=\"avia_inline_auto\" id=\"style-css-av-676rlj-d399e3cb8998c9734da70898478a48ff\">\n.av_font_icon.av-676rlj-d399e3cb8998c9734da70898478a48ff{\ncolor:#7bb0e7;\nborder-color:#7bb0e7;\n}\n.av_font_icon.av-676rlj-d399e3cb8998c9734da70898478a48ff .av-icon-char{\nfont-size:22px;\nline-height:22px;\n}\n<\/style>\n<span  class='av_font_icon av-676rlj-d399e3cb8998c9734da70898478a48ff avia_animate_when_visible av-icon-style- avia-icon-pos-left avia-icon-animate'><span class='av-icon-char' aria-hidden='true' data-av_icon='\ue881' data-av_iconfont='entypo-fontello' ><\/span><\/span><\/h5>\n<h6><u>For further information <\/u><strong>:<\/strong><\/h6>\n<p>Nano Letters : <a class=\"\" href=\"https:\/\/pubs.acs.org\/doi\/10.1021\/acs.nanolett.3c04602\" target=\"_blank\" rel=\"noopener\">https:\/\/pubs.acs.org\/doi\/10.1021\/acs.nanolett.3c04602<\/a><\/p>\n<p>ArXiv : <a class=\"\" href=\"https:\/\/arxiv.org\/abs\/2310.08916\" target=\"_blank\" rel=\"noopener\">https:\/\/arxiv.org\/abs\/2310.08916<\/a><\/p>\n<p><strong> <div  class='avia-button-wrap av-1c9a847-a1a1e136be2c03e5e49195f6b1ff058d-wrap avia-button-left  avia-builder-el-16  el_after_av_font_icon  el_before_av_button'><a href='mailto:imen.hnid@univ-lille.fr'  class='avia-button av-1c9a847-a1a1e136be2c03e5e49195f6b1ff058d av-link-btn avia-icon_select-yes-left-icon avia-size-small avia-position-left avia-color-silver'   aria-label=\"Contact: Imen Hnid\"><span class='avia_button_icon avia_button_icon_left' aria-hidden='true' data-av_icon='\ue805' data-av_iconfont='entypo-fontello'><\/span><span class='avia_iconbox_title' >Contact: Imen Hnid<\/span><\/a><\/div>. \u00a0 <\/strong><strong><div  class='avia-button-wrap av-ltr93r-ffb0c5b1751b4781c56c30797f8ea52c-wrap avia-button-left  avia-builder-el-17  el_after_av_button  avia-builder-el-last'><a href='mailto:dominique.vuillaume@iemn.fr'  class='avia-button av-ltr93r-ffb0c5b1751b4781c56c30797f8ea52c av-link-btn avia-icon_select-yes-left-icon avia-size-small avia-position-left avia-color-silver'   aria-label=\"Contact: Dominique Vuillaume\"><span class='avia_button_icon avia_button_icon_left' aria-hidden='true' data-av_icon='\ue805' data-av_iconfont='entypo-fontello'><\/span><span class='avia_iconbox_title' >Contact: Dominique Vuillaume<\/span><\/a><\/div><\/strong><\/p>\n<\/div><\/section><\/div>","protected":false},"excerpt":{"rendered":"","protected":false},"author":20,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[297],"tags":[],"class_list":["post-70071","post","type-post","status-publish","format-standard","hentry","category-newsletter"],"_links":{"self":[{"href":"https:\/\/www.iemn.fr\/en\/wp-json\/wp\/v2\/posts\/70071","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.iemn.fr\/en\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.iemn.fr\/en\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.iemn.fr\/en\/wp-json\/wp\/v2\/users\/20"}],"replies":[{"embeddable":true,"href":"https:\/\/www.iemn.fr\/en\/wp-json\/wp\/v2\/comments?post=70071"}],"version-history":[{"count":0,"href":"https:\/\/www.iemn.fr\/en\/wp-json\/wp\/v2\/posts\/70071\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.iemn.fr\/en\/wp-json\/wp\/v2\/media?parent=70071"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.iemn.fr\/en\/wp-json\/wp\/v2\/categories?post=70071"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.iemn.fr\/en\/wp-json\/wp\/v2\/tags?post=70071"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}