Highly conductive polymer electrodes for polymer light-emitting diodes

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 the polymer polybenzodifuranedione (PBFDO) as a flexible transparent anode instead of rigid ITO. To address issues 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, the PBFDO electrode facilitates efficient carrier injection and transport as well as photon extraction. The device using a PBFDO anode combined with Super Yellow as the light-emitting layer exhibited a threshold voltage of 2.6 V and a maximum luminous efficiency of 12.8 cd A−1, comparable to a device based on an ITO electrode. Furthermore, a flexible device also achieved satisfactory performance (7.7 cd A−1) on a PEN substrate.

Jin Xu, Ke Du, Feng Peng, Zhenzhong Sun, Zhiming Zhong, Weiji Feng, Lei Ying