Conducting polymers are opening new possibilities that are impacting several technologies such as organic thermoelectrics but also opto- and bioelectronics applications.^[1] Among these polymers, PEDOT:PSS is the most successful one that can transport holes. With an electrical conductivity reaching thousands of S cm^-1 and an exceptional ambient stability, this ionic/electronic conductor has been integrated in multiple applications spanning from conducting layer in organic solar cells or light-emitting diodes to active material in sensors and actuators, supercapacitors or thermoelectrics^[2] while being compatible with large scale deposition methods.

However, while PEDOT:PSS only transports holes (p-type), several opto- and bioelectronic applications include devices that require the integration of materials for the transport of both charges; an n-type material able to transport electrons, combined with a p-type material that transport holes.

To fill this gap, several n-type polymers were developed, without entirely reaching the performances of their p-type counterpart PEDOT:PSS. Most of these n-type conducting polymers, when properly doped, demonstrates electron conductivity of tens of S cm^-1. However, their use at the industrial scale is extremely limited due to their processing involving halogenated solvents that are harmful for the environment. Moreover, they usually lack of ambient and thermal stability, and can be hardly overprocessed due to a poor solvent stability, resulting in mediocre performances. Diverse approaches are explored in order to enhance the electrical performances of this class of n-type materials, from design rationalizations and such as the polymeric backbone planarization and increased rigidity.^[3,4]

Here we report on the use of the rigid ladder-type electron-conducting polymer poly(benzimidazobenzophenanthroline) (BBL) composing an n-type conductive ink for printed electronics.^[5] The ink is alcohol-based and composed of nanoparticles of BBL produced from a solvent exchange process. This system is doped using the amine-based polymer poly(ethyleneimine) (PEI) and is processable by spray-coating in air. A thermal activation allows the BBL:PEI thin-film to demonstrate an electrical conductivity up to 8 S cm^-1, with an excellent thermal stability. Interestingly, this film is stable even when washed with common organic solvents typically used for microfabrication. Finally, we employed this material as active layer in thermoelectric generators demonstrating a power output of 56 nW for a ΔT of 50 K per p-n pair, and as ion-electron conductor in an organic electrochemical transistor (OECT) working in n-type depletion-mode regime. This device, coupled with a PEDOT:PSS-based OECT, was used for ternary logic application that is the first of its kind.