Thermally Activated  Delayed Fluorescent Dendrimers that Underpin High-Efficiency Host-Free   Solution-Processed Organic Light-Emitting Diodes

作者：

Dianming Sun^1,2*,  Eimantas Duda³, Xiaochun Fan¹, Rishabh Saxena³,   Ming Zhang¹, Sergey Bagnich³, Xiaohong Zhang^1*,  Anna Köhler^3* and Eli Zysman-Colman^2*

单位：

¹Institute of Functional Nano & Soft Materials (FUNSOM) and Jiangsu   Key Laboratory for Carbon-Based Functional Materials & Devices, Joint  International Research Laboratory of Carbon-Based Functional Materials and   Devices, Soochow University, Suzhou, Jiangsu 215123, P.R. China.

²Organic Semiconductor Centre, EaStCHEM School of Chemistry, University of St Andrews, St Andrews KY16 9ST, UK.

³Soft Matter Optoelectronics, BIMF & BPI, University of Bayreuth, Universitätsstraße 30, 95447 Bayreuth, Germany.

摘要：

The development of high-performance solution-processed organic light-emitting diodes (OLEDs) remains a challenge. An effective solution, highlighted in this work, is to use highly efficient thermally activated delayed fluorescence (TADF) dendrimers as emitters. Here, the design, synthesis, density functional theory (DFT) modeling, and photophysics of three triazine-based dendrimers, tBuCz2pTRZ, tBuCz2mTRZ, and tBuCz2m2pTRZ, are reported, which resolve the conflicting requirements of achieving simultaneously a small ΔE_ST and a large oscillator strength by incorporating both meta- and para-connected donor dendrons about a central triazine acceptor. The solution-processed OLED containing a host-free emitting layer exhibits an excellent maximum external quantum efficiency (EQE_max) of 28.7%, a current efficiency of  98.8 cd A⁻¹, and a power efficiency of 91.3 lm W⁻¹. The device emits with an electroluminescence maximum, λ_EL, of  540 nm and Commission International de l'Éclairage (CIE) color coordinates of (0.37, 0.57). This represents the most efficient host-free solution-processed OLED reported to date. Further optimization directed at improving the charge balance within the device results in an emissive layer containing 30 wt% OXD-7, which leads to an OLED with a similar EQE_max of 28.4% but showing a significantly improved efficiency roll-off where the EQE remains high at 22.7% at a luminance of 500 cd m⁻².

影响因子：

30.849

分区情况：

一区

链接：

https://onlinelibrary.wiley.com/doi/epdf/10.1002/adma.202110344