{"id":62685,"date":"2024-02-22T10:29:05","date_gmt":"2024-02-22T08:29:05","guid":{"rendered":"https:\/\/www.iemn.fr\/articles-temporaires-anglais\/seminaire-pushing-the-limits-of-silicon-light-emission-jimmy-xu-brown-university-usa-2.html"},"modified":"2024-07-23T16:20:51","modified_gmt":"2024-07-23T14:20:51","slug":"seminaire-pushing-the-limits-of-silicon-light-emission-jimmy-xu-brown-university-usa-2","status":"publish","type":"post","link":"https:\/\/www.iemn.fr\/en\/actualites\/seminaire-pushing-the-limits-of-silicon-light-emission-jimmy-xu-brown-university-usa-2.html","title":{"rendered":"Seminar \"2D Metal Halide Perovskites: Energy Gap and Exciton Binding Energy vs. Octahedral Twist and Quantum and Dielectric Confinement\"."},"content":{"rendered":"\n<style type=\"text\/css\" data-created_by=\"avia_inline_auto\" id=\"style-css-av-pzhlyw-ed309f37f9d18262833477ce285002ba\">\n.flex_column.av-pzhlyw-ed309f37f9d18262833477ce285002ba{\nborder-radius:0px 0px 0px 0px;\npadding:0px 0px 0px 0px;\n}\n<\/style>\n<div  class='flex_column av-pzhlyw-ed309f37f9d18262833477ce285002ba av_one_full  avia-builder-el-0  avia-builder-el-no-sibling  first flex_column_div av-zero-column-padding  '     ><section  class='av_textblock_section av-lsso6yt6-00ec7b05fe841991420b65007797bd92 '   itemscope=\"itemscope\" itemtype=\"https:\/\/schema.org\/BlogPosting\" itemprop=\"blogPost\" ><div class='avia_textblock'  itemprop=\"text\" ><h1 style=\"text-align: center;\">S\u00e9minaire<br \/>\n&lsquo;2D Metal Halide Perovskites: Energy Gap and Exciton Binding Energy vs. Octahedral Twist and Quantum and Dielectric Confinement\u00a0\u00bb&lsquo;<\/h1>\n<h3 style=\"text-align: center;\">Prof. Antoine Khan, Princeton University<\/h3>\n<\/div><\/section><br \/>\n\n<style type=\"text\/css\" data-created_by=\"avia_inline_auto\" id=\"style-css-av-lssocoai-bd7093a2b7d5ca5994f938f65d4ee3ca\">\n#top .av_textblock_section.av-lssocoai-bd7093a2b7d5ca5994f938f65d4ee3ca .avia_textblock{\nfont-size:14px;\n}\n<\/style>\n<section  class='av_textblock_section av-lssocoai-bd7093a2b7d5ca5994f938f65d4ee3ca '   itemscope=\"itemscope\" itemtype=\"https:\/\/schema.org\/BlogPosting\" itemprop=\"blogPost\" ><div class='avia_textblock'  itemprop=\"text\" ><h5>ABSTRACT:<\/h5>\n<div class=\"\"><\/div>\n<div class=\"\">\n<p>Two-dimensional (2D) halide perovskites exhibit remarkable tunability of optoelectronic properties and good environmental stability achieved through the selection of organic cations. In particular, the incorporation of bifunctional ligands featuring non-ammonium terminus and functional groups capable\u00a0of forming extra bonding motifs within the organic bilayer provides an effective strategy to engineer perovskite structures and introduce additional functionalities. 2D halide perovskites are therefore poised to perform an important role, both active and passive, in the developing halide perovskite device\u00a0field.<br class=\"\" \/><br class=\"\" \/>This talk addresses the determination of optoelectronic properties, i.e. single particle gap (EG) and exciton binding energy (EB), in several groups of Ruddlesden-Popper (RP) and Dion-Jacobson (DJ) 2D metal halide perovskites via direct and inverse photoemission spectroscopy (UPS\/IPES) aided by density\u00a0functional theory (DFT). We first determine the electronic gap progression as a function of inorganic layer thickness in high purity films of BA2MAn-1PbnI3n+1\u00a0(n\u00a0= 1-5).[1] We show that this series exhibits a type I, nested band gap heterostructure arrangement. By subtracting the optical from the electronic\u00a0gap, we show that EB\u00a0vs.\u00a0n\u00a0ranges from 420 meV (n\u00a0= 1) down to 100 meV (n\u00a0= 5), well fitted by the empirical scaling law developed by Blancon et al.[2] We then turn to 2D RP perovskites incorporating organic ligands with diverse functional groups (-CN, -OH, -COOH, -Ph, and -CH3), each exhibiting distinct\u00a0bonding characteristics and dielectric properties, and report on the impact of these bifunctional ligands on the electronic and excitonic properties of these 2D perovskites.[3] These bifunctional ligands featuring non-ammonium terminus and functional groups form extra bonding motifs within the organic\u00a0bilayer and provide an effective strategy to engineer perovskite structures and introduce additional functionalities. We observe a strong correlation between EG\u00a0of the -CN, -COOH, -Ph, and -CH3-based perovskites and the in-plane Pb-I-Pb bond angle, aligning with earlier findings regarding the relationship\u00a0between optical gaps and in-plane Pb-I-Pb bond angle.[4,5] The -OH-based perovskite exhibits a significantly deviation from this correlation, attributed to band dispersion in the\u00a0\u00a0out-of-plane direction caused primarily by interlayer electronic coupling. EB\u00a0in these 2D layers is found to range from 360 meV\u00a0for (CH3\u2013PA)2PbI4\u00a0to 70 meV for (OH\u2013EA)2PbI4, a variation attributed to specific structural aspects, such as in-plane Pb-I-Pb bond angle, interlayer spacing, and the dielectric constant of the bifunctional ligands. Overall, these results provide deeper insight into the complex impact of organic ligands on the\u00a0electronic and excitonic properties of 2D perovskites, in particular the substantial role of interlayer electronic coupling.\u00a0<br class=\"\" \/><br class=\"\" \/><em>[1] X. Zhong et al.,\u00a0Adv. Energy Mater.\u00a012, 2202333 (2022)<\/em><br class=\"\" \/><em>[2] J.C. Blancon et al.,\u00a0Nat. Commun.\u00a09, 2254 (2018)<\/em><br class=\"\" \/><em>[3] X. Zhong et al., Adv. Energy Mater., 2304345 (2024)<\/em><br class=\"\" \/><em>[4] S. Silver et al.,\u00a0Adv. Energy Mater.\u00a010, 1903900 (2020)<\/em><br class=\"\" \/><em>[5] X. Zhao et al., Nat. Commun.\u00a013, 3970 (2022)<\/em><\/p>\n<\/div>\n<div><\/div>\n<div>\n<div class=\"\">\n<h3><b class=\"\">Antoine Kahn bio<\/b>.<\/h3>\n<\/div>\n<div class=\"\"><\/div>\n<div class=\"\">\n<div class=\"\">\u2022 Ph.D., Princeton University, 1978<\/div>\n<div class=\"\">\u2022 M.S., Electrical Engineering, Princeton University, 1976<\/div>\n<div class=\"\">\u2022 Diploma of Engineer in Electronics, Institut National Polytechnique de Grenoble, 1974<\/div>\n<\/div>\n<div class=\"\"><\/div>\n<div class=\"\">Stephen C. Macaleer &rsquo;63 Professor in Engineering and Applied Science<br class=\"\" \/>Vice Dean, School of Engineering and Applied Science<br class=\"\" \/>Associated Faculty in the Princeton Materials Institute (PMI)<br class=\"\" \/><br class=\"\" \/>My research programs center on the electronic, chemical, structural\u00a0and electrical properties of materials relevant to thin-film electronic\u00a0devices. My interests span a range of semiconductor materials\u00a0(elemental\u00a0and compounds), but my current work focuses specifically on organic\u00a0molecular and polymer semiconductors, dielectrics developed for\u00a0applications in organic and molecular electronics, and the hot\u00a0new class\u00a0of optoelectronic materials called hybrid metal halide perovskites\u00a0(MHP). Our group is particularly interested in engineering materials and\u00a0interfaces that improve the performance of devices, with\u00a0application to\u00a0organic light-emitting diodes (OLEDs), field-effect transistors\u00a0(OFETs), organic photovoltaic cells (OPVs), MHP-based solar cells and\u00a0light-emitting diodes, and other thin-film devices applicable to\u00a0large-area, flexible electronics.<br class=\"\" \/>\u00a0<br class=\"\" \/>On the organic scene, the quasi-infinite possibilities for chemical\u00a0synthesis of new organic molecular compounds, combined with the\u00a0unmatched ease of fabrication of organic semiconductor films by vacuum\u00a0evaporation, liquid processing or printing on a variety of substrates,\u00a0give organic semiconductors key advantages over other semiconductor\u00a0materials, and open tremendous opportunities for innovation in\u00a0device\u00a0structures. Our research spans fundamental issues of electron-hole\u00a0interaction in molecular semiconductors; chemistry and electronic\u00a0structure of metal-organic and organic-organic heterojunctions;\u00a0physics,\u00a0implementation and impact of chemical (n- and p-) doping to control\u00a0conductivity and carrier injection.<br class=\"\" \/>\u00a0<br class=\"\" \/>On the metal halide perovskite side, our work contributes to a better\u00a0understanding of surface and interface properties of these fascinating\u00a0materials. We are investigating their interfaces with metal oxides and\u00a0organics (small molecules and polymers alike), which are all central to\u00a0device performance.<br class=\"\" \/>\u00a0<br class=\"\" \/>Our group is involved in extensive collaborations with synthetic\u00a0chemists, theoreticians, and device physicists in the US, Asia, and\u00a0Europe, in academia, national laboratories, and industry. Our approach\u00a0involves\u00a0a variety of spectroscopic techniques for determining\u00a0electronic structures, charge carrier transport measurements,\u00a0morphological and structural tools, and device fabrication.<\/div>\n<\/div>\n<\/div><\/section><\/p><\/div>\n","protected":false},"excerpt":{"rendered":"","protected":false},"author":20,"featured_media":69379,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":"","_members_access_role":[],"_members_access_error":""},"categories":[8],"tags":[],"class_list":["post-62685","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-actualites"],"_links":{"self":[{"href":"https:\/\/www.iemn.fr\/en\/wp-json\/wp\/v2\/posts\/62685","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=62685"}],"version-history":[{"count":0,"href":"https:\/\/www.iemn.fr\/en\/wp-json\/wp\/v2\/posts\/62685\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.iemn.fr\/en\/wp-json\/wp\/v2\/media\/69379"}],"wp:attachment":[{"href":"https:\/\/www.iemn.fr\/en\/wp-json\/wp\/v2\/media?parent=62685"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.iemn.fr\/en\/wp-json\/wp\/v2\/categories?post=62685"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.iemn.fr\/en\/wp-json\/wp\/v2\/tags?post=62685"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}