Enhancing the brightness of CsPbBr3 quantum dot electroluminescence light-emitting diodes by manipulation of PEDOT:PSS films

Abstract

With solution-processability, low-temperature proper energy level and superior stability, poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) is one common hole-transport material for the quantum dot light-emitting diode (QLED) application. However, the conductivity of the traditional PEDOT:PSS is very low, which has an adverse effect on QLED devices. Herein, one surface-annealing method for the PEDOT:PSS film to exchange their original composition and surface morphology is proposed. The advantage of this approach lies in the fact that the conductivity of the PEDOT:PSS film annealed with toluene (1.25 S cm⁻¹) and ethylene glycol (EG, 10.52 S cm⁻¹) are obviously improved compared with the air-annealing method (0.13 S cm⁻¹). The difference is that the EG-washed PEDOT:PSS film shows a relatively rough surface with more PEDOT domains, whereas the toluene treated PEDOT:PSS film can promote the formation of a smooth, PSS-dominated surface and change the PEDOT chain structure from coiled to linear, thus, the conductivity of the PEDOT:PSS film is enhanced. As a result, the QLED device achieves a maximum luminance of 31 140 cd m⁻² and power efficiency of 13.4 lm W⁻¹, showing 48% and 25% enhancements, respectively, compared to the control device. This work provides an efficient approach for improving of perovskite QLED performance.