Shengyu Li, Zhi Yang, Yanchao Xie, Lei Hua, Shian Ying, Yuchao Liu, Zhongjie Ren and Shouke Yan
{"title":"Modulatory spin-flip of triplet excitons via diversiform electron-donating units for MR-TADF emitters towards solution-processed narrowband OLEDs†","authors":"Shengyu Li, Zhi Yang, Yanchao Xie, Lei Hua, Shian Ying, Yuchao Liu, Zhongjie Ren and Shouke Yan","doi":"10.1039/D4SC05516K","DOIUrl":null,"url":null,"abstract":"<p >Multiple resonance thermally activated delayed fluorescence (MR-TADF) molecules are emerging as promising candidates for high-resolution organic light-emitting diode (OLED) displays, but MR-TADF emitters always suffer from an unsatisfactory rate constant of reverse intersystem crossing (<em>k</em><small><sub>RISC</sub></small>) due to inherently low spin orbital coupling strength between excited singlet and triplet states. Herein, we systematically investigate the long-range charge transfer (LRCT) and heavy-atom effects on modulating the excited state natures and energy levels <em>via</em> integrating diversiform electron-donating units with the MR skeleton. Compared with unsubstituted analogues, newly designed MR-TADF emitters exhibit significantly boosted <em>k</em><small><sub>RISC</sub></small> values and close-to-unity photoluminescence quantum yield especially for <strong><em>t</em>BuCzBN-PXZ</strong> (2.5 × 10<small><sup>5</sup></small> s<small><sup>−1</sup></small>) and <strong><em>t</em>BuCzBN-Ph-PSeZ</strong> (2.1 × 10<small><sup>5</sup></small> s<small><sup>−1</sup></small>). Leveraging these exceptional properties, the maximum external quantum efficiency values of <strong><em>t</em>BuCzBN-PXZ</strong>- and <strong><em>t</em>BuCzBN-Ph-PSeZ</strong>-based solution-processed OLEDs can reach 21.3% and 19.4%, which are in the first tier of reported solution-processed MR-TADF binary OLEDs without employing additional sensitizers. This study provides a framework for modulating photoelectrical properties of MR-TADF emitters through fastidiously regulating LRCT and heavy-atom effects.</p>","PeriodicalId":9909,"journal":{"name":"Chemical Science","volume":" 44","pages":" 18335-18346"},"PeriodicalIF":7.6000,"publicationDate":"2024-10-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://pubs.rsc.org/en/content/articlepdf/2024/sc/d4sc05516k?page=search","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Chemical Science","FirstCategoryId":"92","ListUrlMain":"https://pubs.rsc.org/en/content/articlelanding/2024/sc/d4sc05516k","RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"CHEMISTRY, MULTIDISCIPLINARY","Score":null,"Total":0}
引用次数: 0
Abstract
Multiple resonance thermally activated delayed fluorescence (MR-TADF) molecules are emerging as promising candidates for high-resolution organic light-emitting diode (OLED) displays, but MR-TADF emitters always suffer from an unsatisfactory rate constant of reverse intersystem crossing (kRISC) due to inherently low spin orbital coupling strength between excited singlet and triplet states. Herein, we systematically investigate the long-range charge transfer (LRCT) and heavy-atom effects on modulating the excited state natures and energy levels via integrating diversiform electron-donating units with the MR skeleton. Compared with unsubstituted analogues, newly designed MR-TADF emitters exhibit significantly boosted kRISC values and close-to-unity photoluminescence quantum yield especially for tBuCzBN-PXZ (2.5 × 105 s−1) and tBuCzBN-Ph-PSeZ (2.1 × 105 s−1). Leveraging these exceptional properties, the maximum external quantum efficiency values of tBuCzBN-PXZ- and tBuCzBN-Ph-PSeZ-based solution-processed OLEDs can reach 21.3% and 19.4%, which are in the first tier of reported solution-processed MR-TADF binary OLEDs without employing additional sensitizers. This study provides a framework for modulating photoelectrical properties of MR-TADF emitters through fastidiously regulating LRCT and heavy-atom effects.
期刊介绍:
Chemical Science is a journal that encompasses various disciplines within the chemical sciences. Its scope includes publishing ground-breaking research with significant implications for its respective field, as well as appealing to a wider audience in related areas. To be considered for publication, articles must showcase innovative and original advances in their field of study and be presented in a manner that is understandable to scientists from diverse backgrounds. However, the journal generally does not publish highly specialized research.