Research Paper: Impact of the Electrode Material on the Performance of Light-Emitting Electrochemical Cells
Scientific Summary
This study investigates the impact of electrode material on Light-Emitting Electrochemical Cell (LEC) performance, challenging the common assumption of electrode independence. Its goal was to demonstrate how electrode work function influences the exciton generation zone (EGZ) and how electrode choice affects exciton losses to surface plasmon polaritons (SPPs) and cavity effects. Findings reveal that cathode material, via its electron injection barrier, significantly shifts the EGZ (e.g., Ca shifts it towards the anode due to more available ions). SPP losses are heavily electrode-dependent in thin-film LECs, with Ca causing the strongest quenching. Optical cavity properties further influence exciton decay and density. The study concludes that optimised LEC design requires holistic consideration of electrode materials, active-material thickness, and composition, corroborated by optical model replication of measured luminance transients.
Fluxim Tools Used
The commercial software Setfos was instrumental for all simulations. Setfos enabled comprehensive optical analysis to: determine the Center of the Exciton Generation Zone (CEG) by fitting simulated angle-dependent emission spectra to experimental data; quantify Surface Plasmon Polariton (SPP) losses via simulations; model exciton density and effective radiative decay rates; and calculate/reproduce forward luminance transients. This provided predictive insights for LEC optimisation.
Why the Findings Matter
This research refines LEC physics, disproving electrode independence, crucial for widespread adoption. As LECs promise sustainable, solution-processed lighting, performance optimisation is vital. The study offers rational design criteria, highlighting the necessity of considering electrode materials, active-material thickness, and composition for optimal efficiency and stability. Setfos's optical modelling was key to these insights, aiding the development of better LECs and potentially enabling reduced salt concentrations to mitigate exciton-polaron quenching.
Publication Details
Kirch, A., Park, S.-R., Raf̀ols-Ribé, J., Kassel, J.A., Zhang, X., Tang, S., Larsen, C. and Edman, L. (2025), Impact of the Electrode Material on the Performance of Light-Emitting Electrochemical Cells. ACS Appl. Mater. Interfaces, 17, 5184−5192. https://pubs.acs.org/doi/10.1021/acsami.4c18009.