The Improvement of the Performance of Sky-Blue OLEDs by Decreasing Interface Traps and Balancing Carriers with PSVA Treatment

Abstract

The mitigation of interfacial charge accumulation in solution-processed organic light-emitting diodes (s-OLEDs) is an effective method to improve device performance. In this study, the polar solvent vapor annealing (PSVA) method was used to treat two layers in s-OLED, PEDOT:PSS and mCP:DMAC-DPS emitting layers, separately, to optimize the carrier transmission and balance. After the double-layer PSVA treatment, the current efficiency increased, the lifetime of the device is improved, the efficiency roll-off alleviated from 33.3% to 26.6%, and the maximum brightness increased by 31.3%. It is worth mentioning that the work function of the EML interface reduced by 0.36 eV, and the initial injection voltage of the electrons also reduced. Simulating the solubility of the LUMO and HOMO molecule parts of the mCP and DMAC-DPS, it was found that the LUMO parts had stronger polarity and higher solubility in polar solution than the HOMO parts. By comparing the untreated luminescent layer films, it was found that the PSVA treatment improved the uniformity of the film morphology. We may infer that a more ordered molecular arrangement enhances carrier transport as the LUMO parts tend to be close to the surface and the reduced local state traps on the EML surface promote electron injection. According to the experimental results, the injection of holes and electrons is enhanced from both sides of the EML, respectively, and the charge accumulated at the interface of s-OLEDs is significantly reduced due to the improvement of carrier-transported characteristics.

Intrinsically Stretchable Emissive Layer for Green and Red Phosphorescent OLEDs: Small Molecules Blended with SEBS Elastomer

“…This, in turn, leads to lower current flow and a serious roll‐off in efficiency. [ 15 ] Adding elastomers (SEBS, PU) into the emitting polymer (SY) significantly decreases the device efficiency. The current efficiency of the PLED device with the same structure, but without elastomer in the EML, was reported to be two times higher.…”

The Optimization of Hole Injection Layer in Organic Light-Emitting Diodes

“…Furthermore, optimizing the carrier injection could employ the polar solvent vapor annealing (PSVA) method, resulting in a significant reduction in charge accumulation at the OLED interface. After the double-layer PSVA treatment, the efficiency roll-off of OLEDs dropped from 33.3% to 26.6% [ 113 ].…”

Shedding Light on Eu(III) β‐Diketonate Compounds with 1,2‐Bis(diphenylphosphino)ethane Oxide Ligand: an Optical Study

“…As a result, several highly luminescent complexes with β‐diketonate and carboxylate ligands, particularly of the Eu 3+ and Tb 3+ ions, have been synthesized [2a,b] . Many of them have potential applications for optical sensing, [3a] light‐emitting devices [3b,c] luminescent thermometers, [3d] optoelectronics, [3e] and theragnostic & bio‐imaging [3f,g] …”