He Liu, Yang Liu, Guohao Chen, Yuan Meng, Hao Peng, Jingsheng Miao and Chuluo Yang
{"title":"非平面结构加速了 TADF 发射器的反向系统间穿越:EQE 接近 40%,效率衰减得到缓解","authors":"He Liu, Yang Liu, Guohao Chen, Yuan Meng, Hao Peng, Jingsheng Miao and Chuluo Yang","doi":"10.1039/D4SC03111C","DOIUrl":null,"url":null,"abstract":"<p >Exploring strategies to enhance reverse intersystem crossing (RISC) is of great significance to develop efficient thermally activated delayed fluorescent (TADF) molecules. In this study, we investigate the substantial impact of nonplanar structure on improving the rate of RISC (<em>k</em><small><sub>RISC</sub></small>). Three emitters based on spiroacridine donors are developed to evaluate this hypothesis. All molecules exhibit high photoluminescent quantum yields (PLQYs) of 96–98% due to their rigid donor and acceptor. Leveraging the synergistic effects of heavy element effect and nonplanar geometry, <strong>S2-TRZ</strong> exhibits an accelerated <em>k</em><small><sub>RISC</sub></small> of 24.2 × 10<small><sup>5</sup></small> s<small><sup>−1</sup></small> compared to the 11.1 × 10<small><sup>5</sup></small> s<small><sup>−1</sup></small> of <strong>S1-TRZ</strong>, which solely incorporates heavy atoms. Additionally, <strong>O1-TRZ</strong> possesses a further lower <em>k</em><small><sub>RISC</sub></small> of 9.42 × 10<small><sup>5</sup></small> s<small><sup>−1</sup></small> because of the absence of these effects. Remarkably, owing to the high PLQYs and suitable TADF behaviors, devices based on these emitters exhibit state-of-the-art performance, including a maximum external quantum efficiency of up to 40.1% and maximum current efficiency of 124.7 cd A<small><sup>−1</sup></small>. More importantly, devices utilizing <strong>S2-TRZ</strong> as an emitter achieve a relieved efficiency roll-off of only 7% under 1000 cd m<small><sup>−2</sup></small>, in contrast to the 12% for <strong>O1-TRZ</strong> and 11% for <strong>S1-TRZ</strong>, respectively. These findings advance our fundamental understanding of TADF processes for high-performance electroluminescent devices.</p>","PeriodicalId":9909,"journal":{"name":"Chemical Science","volume":null,"pages":null},"PeriodicalIF":7.6000,"publicationDate":"2024-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://pubs.rsc.org/en/content/articlepdf/2024/sc/d4sc03111c?page=search","citationCount":"0","resultStr":"{\"title\":\"Nonplanar structure accelerates reverse intersystem crossing of TADF emitters: nearly 40% EQE and relieved efficiency roll off†\",\"authors\":\"He Liu, Yang Liu, Guohao Chen, Yuan Meng, Hao Peng, Jingsheng Miao and Chuluo Yang\",\"doi\":\"10.1039/D4SC03111C\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<p >Exploring strategies to enhance reverse intersystem crossing (RISC) is of great significance to develop efficient thermally activated delayed fluorescent (TADF) molecules. In this study, we investigate the substantial impact of nonplanar structure on improving the rate of RISC (<em>k</em><small><sub>RISC</sub></small>). Three emitters based on spiroacridine donors are developed to evaluate this hypothesis. All molecules exhibit high photoluminescent quantum yields (PLQYs) of 96–98% due to their rigid donor and acceptor. Leveraging the synergistic effects of heavy element effect and nonplanar geometry, <strong>S2-TRZ</strong> exhibits an accelerated <em>k</em><small><sub>RISC</sub></small> of 24.2 × 10<small><sup>5</sup></small> s<small><sup>−1</sup></small> compared to the 11.1 × 10<small><sup>5</sup></small> s<small><sup>−1</sup></small> of <strong>S1-TRZ</strong>, which solely incorporates heavy atoms. Additionally, <strong>O1-TRZ</strong> possesses a further lower <em>k</em><small><sub>RISC</sub></small> of 9.42 × 10<small><sup>5</sup></small> s<small><sup>−1</sup></small> because of the absence of these effects. Remarkably, owing to the high PLQYs and suitable TADF behaviors, devices based on these emitters exhibit state-of-the-art performance, including a maximum external quantum efficiency of up to 40.1% and maximum current efficiency of 124.7 cd A<small><sup>−1</sup></small>. More importantly, devices utilizing <strong>S2-TRZ</strong> as an emitter achieve a relieved efficiency roll-off of only 7% under 1000 cd m<small><sup>−2</sup></small>, in contrast to the 12% for <strong>O1-TRZ</strong> and 11% for <strong>S1-TRZ</strong>, respectively. 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Nonplanar structure accelerates reverse intersystem crossing of TADF emitters: nearly 40% EQE and relieved efficiency roll off†
Exploring strategies to enhance reverse intersystem crossing (RISC) is of great significance to develop efficient thermally activated delayed fluorescent (TADF) molecules. In this study, we investigate the substantial impact of nonplanar structure on improving the rate of RISC (kRISC). Three emitters based on spiroacridine donors are developed to evaluate this hypothesis. All molecules exhibit high photoluminescent quantum yields (PLQYs) of 96–98% due to their rigid donor and acceptor. Leveraging the synergistic effects of heavy element effect and nonplanar geometry, S2-TRZ exhibits an accelerated kRISC of 24.2 × 105 s−1 compared to the 11.1 × 105 s−1 of S1-TRZ, which solely incorporates heavy atoms. Additionally, O1-TRZ possesses a further lower kRISC of 9.42 × 105 s−1 because of the absence of these effects. Remarkably, owing to the high PLQYs and suitable TADF behaviors, devices based on these emitters exhibit state-of-the-art performance, including a maximum external quantum efficiency of up to 40.1% and maximum current efficiency of 124.7 cd A−1. More importantly, devices utilizing S2-TRZ as an emitter achieve a relieved efficiency roll-off of only 7% under 1000 cd m−2, in contrast to the 12% for O1-TRZ and 11% for S1-TRZ, respectively. These findings advance our fundamental understanding of TADF processes for high-performance electroluminescent devices.
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.