Solution Processable Material Derived from Aromatic Triazole, Azomethine and Tris: Preparation and Hole-Buffering Application in Polymer Light-Emitting Diodes

Abstract

This work presents the synthesis of a new hole-buffering material TAZS and its successful application in polymer light-emitting diodes to enhance device performance. The TAZS is composed of aromatic 1,2,4-triazolylcore linked with three trihydroxy tert-butyl terminals via azomethine linkages. The TAZS forms ashomogeneous film deposited by spin-coating process. The HOMO and LUMO levels of TAZS are −5.23 eV and −2.40 eV, respectively, as estimated from cyclic voltammogram. The current density results of hole-only and electron-only devices confirm strong hole-buffering capability of TAZS layer. Multilayer PLEDs with different thickness of TAZS (ITO/PEDOT: PSS/TAZS (x nm)/SY/ETL/LiF/Al) have been successfully fabricated, using spin-coating process to deposit hole-injecting PEDOT: PSS, TAZS, and emissive SY layers. The PLED with 16 nm TAZS reveals the optimal device performance, with maximum luminance and maximum current efficiency of 19,046 cd/m 2 and 4.08 cd/A, respectively, surpassing those without TAZS as HBL (8484 cd/m 2 , 2.13 cd/A). The hole-buffering characteristic of TAZS contributes greatly to improved charges' recombination ratio and enhanced emission efficiency.