Anionic Low Band Gap-Conjugated Polyelectrolytes as Hole-Transporting Layer in Optoelectronics Devices

In the last years, interfacial engineering has played a critical role in promoting the performance of optoelectronic devices as organic solar cells (OSC) and organic light-emitting diodes (OLEDs) since interfacial layers help to form an ohmic contact between the electrodes and the active layers, which is of great importance for charge collection/injection. Conjugated polyelectrolytes (CPEs), which are conjugated polymers bearing side-chain ionic functionalities such as anionic, cationic, or zwitterionic groups, have emerged as a new class of interfacial materials in thin film-based electronic devices thanks to their ability to reduce the barrier between electrode and active layer. In view of this, we designed and synthesized two novel low bandgap anionic copolymers with different anionic pendant groups and different conjugated backbones to obtain hole-transporting layer (HTL) materials as an alternative to commonly used poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate). The functional behavior of these copolymers as anode modifiers is herein preliminarily investigated in an OLED prototype.