Screens are becoming ever smaller and increasingly sharper. This can be seen, for example, in augmented reality glasses or in the electronic viewfinders of cameras, some of which have a screen diagonal of less than one centimetre.<\/p>\n
However, the smaller the screen pixels, the more difficult they are to manufacture. Organic light-emitting diodes (OLEDs) show great promise for particularly small pixels. Unlike conventional light-emitting diodes, they are not made of crystals but of carbon-based compounds. Whilst conventional light-emitting diodes become dimmer the smaller the crystals are cut, organic light-emitting materials can be used to produce tiny yet bright pixels.<\/p>\n
Until now, the organic light-emitting materials were not suitable for the high-precision manufacturing methods used in the semiconductor industry. The photolithography used in this industry involves solvents and other chemicals that chemically attack and degrade the organic molecules.<\/p>\n
Photoresists for lithography<\/p>\n
Researchers at ETH Zurich have now succeeded in making organic luminescent molecules suitable for photolithography: they have produced luminescent polymers in various colours that serve as photoresists whilst withstanding harsh chemical conditions. The polymers can be applied to a semiconductor chip. Photoresist properties cross-link when exposed to UV light, enabling the creation of fine-scale geometric structures.<\/p>\n
“We’ve developed a new class of long-chain molecules that can be manufactured into OLED pixels using direct light exposure,” says Yinyin Bao, who conducted research at ETH Zurich and is now a professor at the University of Helsinki. He led the research together with ETH Professor Chih-Jen Shih. They have now published their findings in the journal external page Nature<\/a> .<\/p>\n Protective shell, luminescent core<\/p>\n To protect the sensitive luminescent molecules from aggressive chemicals, the researchers developed a molecular complex based on the core-shell principle: at its centre lies the colour-emitting molecule. Surrounding it are arms arranged in a star-like pattern, the outer ends of which react to UV light. When exposed to light, they cross-link with the arms of other stars. This renders the material insoluble in that area, a property utilised in photolithography.<\/p>\n The inner part of the arms also fulfils an important function: it keeps the reactive ends at a distance from the luminescent molecule, thereby shielding it. A co-author of the study from the RMIT University in Melbourne further investigated this protective effect using computer simulations.<\/p>\n","protected":false},"excerpt":{"rendered":"Screens are becoming ever smaller and increasingly sharper. This can be seen, for example, in augmented reality glasses…\n","protected":false},"author":2,"featured_media":902340,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[6],"tags":[64,63,105],"class_list":["post-902339","post","type-post","status-publish","format-standard","has-post-thumbnail","category-technology","tag-au","tag-australia","tag-technology"],"_links":{"self":[{"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/posts\/902339","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/comments?post=902339"}],"version-history":[{"count":0,"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/posts\/902339\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/media\/902340"}],"wp:attachment":[{"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/media?parent=902339"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/categories?post=902339"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/tags?post=902339"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}