Alkylamine-Doping Poly(3,4-ethylene dioxythiophene):Poly(styrene sulfonic acid)-Enhanced Operational Stability of Perovskite Light-Emitting Diodes: Chain Length Effect

Due to its high transparency, low refractive index, tunable conductivity, and thermal stability, poly(3,4-ethylene dioxythiophene):poly(styrene sulfonic acid) (PEDOT:PSS) is commonly used as a hole transport layer (HTL) material of perovskite light-emitting diodes (PeLEDs). However, PEDOT:PSS is highly acidic and sensitive to humidity, which would corrode the perovskite layer and result in poor operational stability of PeLEDs. Here, we modified the PEDOT:PSS by doping a series of n-alkylamines with different chain lengths. Alkylamines neutralize the acidity of PEDOT:PSS and form a hydrophobic layer, which blocks the ion migration between HTL and the emitting layer and promotes the device operational stability. Overall, the PeLEDs exhibit alkylamine chain length-related efficiency and luminance. The operational half-lifetime of the PeLEDs almost increases as the chain length of the alkylamine increases. We obtained a high-stability PeLED based on a modified HTL with a lifetime of 36.4 h, which is a seven times improvement compared to the pristine device. Our findings offer a method to enhance the operational stability of PeLEDs and provide insights into the interaction between the HTL and perovskite layer.