Sustainable light-emitting devices through control of dynamic doping

Artificial illumination is fundamental and ubiquitous in modern society, and the cuArtificial illumination is fundamental and ubiquitous in modern society, and the current large-scale commercialization of more efficient and practical technologies, in the form of LEDs and OLEDs, is therefore important.

This development is not only resulting in improved luminaires and displays, but also paving the way for a wide range of applications in, e.g., medtech, security, and communication.

However, a growing concern is related to that the fabrication of LEDs and OLEDs consumes large amounts of critical raw materials (CRMs) and energy, and that their recycling is poorly developed and difficult.A novel illumination technology, the light-emitting electrochemical cell (LEC), is in this context interesting, and we and others have recently developed concepts for its material- and energy-efficient and CRM-free printing fabrication and its delivery of efficient emission (although not yet on par with LED/OLED).

These combined achievements now pave the way for a timely and important challenge: can the LEC become the first emissive technology that is truly sustainable through its entire lifecycle?We boldly argue that this vision can turn true if we can take control of the defining LEC feature, viz. the dynamic formation of a p-n junction by electrochemical doping.

It was recently shown that current LECs suffer from severe quenching of the excitons (the photon precursors formed in the p-n junction) by too-nearby dopants, and we here introduce new insights and methodologies that address this setback through rational design and careful development of new materials.

A key task is to tune the mobility of the electronic charge carriers and excitons, through guidelines established by modeling, for the attainment of a sharp p-n junction boundary.

We emphasize that our proposed path to high-efficiency LECs does not depend on energy-intense processes or the use of toxic or CRM-based materials.