Improved performance of flexible perovskite light-emitting diodes with modified PEDOT:PSS hole transport layer

We demonstrated the improved device performance of flexible perovskite light-emitting diodes (PeLEDs) on indium-tin oxide coated poly(ethylene terephthalate) (ITO/PET) substrates by using modified poly(3,4-ethylene dioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) as a hole transport layer (HTL). Solvent modification and dopant modification of the PEDOT:PSS solution were carried out by adding isopropyl alcohol (IPA) and poly(sodium 4-styrenesulfonate) (PSS-Na), respectively, to the pristine solution. Devices with the modified HTLs, PEDOT:PSS + IPA and PEDOT:PSS + PSS-Na, exhibited a significant enhancement in both luminance and efficiency. The work function of HTL was improved to reduce the energy barrier against the perovskite layer and facilitate hole transport. The perovskite films deposited on the modified PEDOT:PSS layers showed a uniformly covered surface morphology without any defects, resulting in an increased PL intensity. In particular, the perovskite film coated on the dopant modified HTL showed a better crystallinity and reduced luminescence quenching. The PeLED device with the PEDOT:PSS + PSS-Na HTL exhibited a maximum luminance of 3900 cd/m2, a maximum current efficiency of 25.1 cd/A, and a maximum external quantum efficiency of 5.9%.