An Efficient Hole Transporting Polymer for Quantum Dot Light‐Emitting Diodes

Abstract

Ideal hole transporting polymers used in quantum dot (QD) light‐emitting diodes (QLEDs) should possess the features such as high conductivities and stabilized highest occupied molecular orbitals (HOMOs). Herein, an efficient polymer (named CNPr‐TFB) is achieved by rationally adding a relatively weak electron‐withdrawing group (2‐cyanopropan‐2‐yl, CNPr) on a TFB like hole transporting polymer. CNPr‐TFB exhibits a superior hole conductivity and much more stabilized HOMO in comparison with TFB. Therefore, much more holes are delivered into the QD emissive layers and a balanced recombination of electron and hole in the QLEDs is achieved. The external quantum efficiencies of the red, green, blue, and white QLEDs made by CNPr‐TFB as the hole transporting layer (HTL) are 20.7%, 16.6%, 11.3%, and 15.0%, respectively, which are increased by 1.4–2.3 times in comparison with those of devices based on the commonly used TFB HTL. Meanwhile, the CNPr‐TFB‐based QLEDs also exhibit longer operation lifetimes than those of devices using the TFB HTL. These results confirm that CNPr‐TFB with the features of high conductivity and stabilized HOMO can be an excellent HTL material for the QLED applications

Single-component electroluminescent white light-emitting diodes based on zinc oxide quantum dots with high color rendition and tunable correlated color temperature

“…3a). Compared to poly-TPD (m h B1.0 Â 10 À4 cm 2 V À1 s À1 ), TFB has a higher hole mobility (m h B1.0 Â 10 À2 cm 2 V À1 s À1 ), 33,34 which is beneficial for hole transportation. Thus, after doping TFB into poly-TPD, the holes can transport more quickly and then be injected into the ZnO-QDs, which results in enhanced green-blue waveband intensity.…”

Cadmium‐Doped Zinc Sulfide Shell as a Hole Injection Springboard for Red, Green, and Blue Quantum Dot Light‐Emitting Diodes

“…Then 100 nm Al was deposited on the top of ZnMgO as the cathode by thermal evaporation (see the Supporting Information). [ 43 ] From the image of cross‐sectional TEM, clear boundaries at the interfaces of EML/ETL and EML/HTL were observed (Figure 5b,c ). It is noted that the thickness of R3 is around 20 nm, corresponding to 1.5−2.0 QD layers in D3 .…”

The influence of spinodal decomposition-based phase separation in a hybrid polymer hole transport layer on electroluminescent quantum dot light-emitting diodes

“…35,41 In contrast, TFB with triphenylamine and fluorene moieties has a higher hole mobility (B1.0 Â 10 À2 cm 2 V À1 s À1 ). 42,43 The hybridization process to utilize the advantages of both polymers is feasible and straightforward. Moreover, both polymers are rather compatible according to their chemical structures and considered to be well dissolved with eath other.…”