Tuning hole injection of poly(3,4-ethylenedioxythiophene):poly (styrenesulfonate) to optimize a quantum dot light-emitting diode

摘要

Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) is considered the best hole injection/extraction material in organic electronic devices. Two types of PEDOT:PSS (AI4083, PH1000) are demonstrated for tuning of hole injection and according optimization of electro-optic performance in a quantum dot light-emitting diode (QLED). In comparison with PEDOT:PSS-AI4083, PEDOT:PSS-PH1000 has inferior QLED performance owing to its higher hole mobility and hence serious carrier imbalance. The effect of PEDOT:PSS-AI4083 concentration is investigated in detail. With CdSe/ZnS quantum dots as the emitter and the optimal concentration of PEDOT:PSS-AI4083 as the hole injection layer, the QLED produces typical green emission with an electroluminescent peak of 527 nm, full width at half maximum of 24 nm and 1931 Commission Internationale d'Eclairage color coordinates of (0.150, 0.784). It gives a maximum luminous efficiency of 18.4 cd A(-1), power efficiency of 5.8 lm W(-1)and external quantum efficiency of 5.9%, with overwhelming superiority over the corresponding references. The current-voltage and impedance spectroscopy analysis of hole-only cells indicates that the hole injection can be facilely tuned by using different types of PEDOT:PSS and/or altering the PEDOT:PSS concentration, which accounts for regulation of carrier balance and optimization of device performance. Our results pave the way to an alternative approach for the lab-to-fab journey of PEDOT:PSS and advancing electronic devices.