Enhanced flexibility and stability of PEDOT:PSS electrodes through interfacial crosslinking for flexible organic light-emitting diodes

Abstract

Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) films have drawn extensive attention as one of the most promising flexible transparent conductive electrodes to replace traditional indium tin oxide. However, some critical issues, such as weak adhesion, vulnerability to moisture and detrimental acidic property, need to be addressed before the practical application and industrialization. Here, we propose a facile and effective strategy of interfacial crosslinking to further improve the flexibility and stability of PEDOT:PSS electrodes with high transparency and conductivity by introducing polyethyleneimine ethoxylated (PEIE) on the surface. The flexibility and stability of PEDOT:PSS electrodes with PEIE overcoating layer are significantly improved, which can be attributed to the interfacial crosslinking reaction between PEIE and PSS. Finally, flexible organic light-emitting didoes (OLEDs) are constructed based on the PEDOT:PSS electrodes modified by PEIE, and current efficiency is enhanced from 20.5 to 76.4 cd/A with a 2.7-fold enhancement, owning to the improved carrier balance. This study confirms that PEIE is effective in protecting the PEDOT:PSS films from mechanical damage and moisture attack, while maintaining the high conductive and transmittance, and illustrates a promising future in low-cost flexible optoelectronic devices employing PEDOT:PSS electrodes. Polyethyleneimine ethoxylated (PEIE) is introduced on the surface of PEDOT:PSS, which improves the flexibility and stability of the highly transparent and conductive PEDOT:PSS electrodes due to the interfacial crosslinking reaction between PEIE and PSS. This approach enhances the luminous efficiency from 20.5 to 76.4 cd/A for flexible organic light-emitting diodes, illustrating a promising future in low-cost flexible optoelectronic devices. • Polyethyleneimine ethoxylated (PEIE) is introduced on the surface of PEDOT:PSS. • The interfacial crosslinking reaction between PEIE and PSS enhanced the flexibility and stability of PEDOT:PSS electrodes. • This approach enhances the luminous efficiency from 20.5 to 76.4 cd/A of flexible organic light-emitting diodes.