Enhancing the electroluminescence performances of blue polymer light emitting devices via carriers transporting materials incorporation

Abstract

A series of polymer light emitting devices (PLEDs) based on the composite films of N-arylbenzimidazoles trimer (TPBI), poly (n-vinylcarbazole) (PVK), and a triarylaminooxadiazole-containing tetraphenylsilane light emitting polymer (PTOA) were investigated. Electroluminescence (EL) performance is enhanced with doped TPBI into the light-emitting layer for the PTOA-based devices. A deep blue emission (Commission Internationale de L'Eclairage (CIE x,y ) corodinates (0.16,0.06)) is obtained for the TPBI-PTOA-based device. Brightness and current efficiency of the TPBI-PTOA-based device can be as high as 961 cd/m 2 and 1.85 cd/A, respectively. The EL performances of TPBI-PTOA composite film-based devices are further enhanced by inserting a TPBI layer into the light emitting layer and cathode interface for a better electron and hole charge balance. Doping TPBI into the light-emitting layer of PVK-PTOA is not favorable for enhanced EL performances. Brightness and current efficiency reduced with increasing TPBI content for the TPBI-PVK-PTOA-based devices. Similar results are obtained for devices based on the TPBI-PVK-PTOA/TPBI bi-layer composite solid film. Morphology and charge balance effects on EL performances of TPBI-PTOA and TPBI-PVK-PTOA composite films based PLEDs are discussed in detail.

Efficient Green Electrophosphorescence with Al Cathode Using an Effective Electron-Injecting Polymer As the Host

“…Significant progress in the improvement of the device performances for PLEDs based on solution processing has been made in recent years; however, the performances of PLED such as the efficiency and operating lifetime have not yet met the requirements of commercial application. To achieve highly efficient electroluminescence, charge balance is of great importance − . Most of the conjugated polymers are p-type semiconductors , which mainly transport holes in the EL processes, and thus enhancing the electron injection and transportation is an effective way to improve the performance of PLED.…”