Highly conductive polymer electrodes for polymer light-emitting diodes

Abstract

Organic light-emitting diodes (OLEDs) offer the advantage of flexibility; however, the use of traditional transparent anode ITO limits further extension of their flexible characteristics. In this study, we propose employing an polymer polybenzodifuranedione (PBFDO) as a flexible transparent anode instead of the rigid ITO. To address the issue encountered during the PBFDO solution spin-coating process, we introduced n-butanol into the PBFDO conductive solution to reduce its viscosity and freezing point by modulating intermolecular hydrogen bonding interactions. Consequently, high-quality PBFDO films with high conductivity, superior transmittance, and low surface roughness were successfully obtained via spin-coating. Moreover, due to its proper work function, regular molecular stacking, and low refractive index properties, PBFDO electrode facilitate efficient carrier injection and transport as well as photon extraction. The resulting device utilizing a PBFDO anode combined with Super Yellow as the light-emitting layer exhibited excellent performance characteristics including a normal threshold voltage of 2.6 V and a maximum luminous efficiency of 12.8 cd A−1 comparable to that device based on the ITO electrode. Furthermore, flexible device also achieved satisfactory performance (7.7 cd A−1) when using the PEN substrate.