Sustainable light-emitting devices through control of dynamic doping

Introduction

Artificial 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.

Concerns with Current Technologies

However, a growing concern is related to the fabrication of LEDs and OLEDs, which consumes large amounts of critical raw materials (CRMs) and energy. Additionally, their recycling is poorly developed and difficult.

Novel Illumination Technology

A novel illumination technology, the light-emitting electrochemical cell (LEC), is interesting in this context. 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).

The Challenge Ahead

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?

Vision for Sustainability

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.

New Insights and Methodologies

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.

Path to High-Efficiency LECs

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.