Investigation of electrospray-deposited PEDOT:PSS thin film using an electrohydrodynamic jet printer for inverted QDLEDs

In general, Poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS) is spin-coated as a hole transport layer in multi-structured quantum dots light-emitting diodes (QDLEDs). However, it is still a challenge to coat hydrophilic PEDOT:PSS on a hydrophobic layer in inverted QDLEDs. Electrohydrodynamic (EHD) jet printing was applied to make thin films from PEDOT:PSS solution on hydrophobic PVK film. The electrospray-deposited films showed precisely controllable thickness, scalability, and extremely low surface roughness (R-a of 0.55 nm). An inverted QDLED device (ITO/ZnO/QDs/PVK/electrosprayed PEDOT:PSS/Al) was prepared based on the understanding of electrospray droplets mechanism, the formation of PEDOT:PSS film on a PVK film, and drying dynamics of the inks. The device shows a current density of 3.7576 cd A(-1), maximum luminance of 5692 cd m(-2), and EQE of 2.2245%.

Automated summary

This study investigates the use of electrospray printing technology to prepare PEDOT:PSS films on hydrophobic PVK films and applies them in inverted QDLED devices. The films have controllable thickness and low surface roughness, and exhibit high current density, maximum luminance, and external quantum efficiency.