Efficient Light-Emitting Electrochemical Cells Based on Optimized Diffusers

Light-emitting electrochemical cells (LECs) have opened up new avenues for cost-effective, flexible light emission applications. However, their efficiency falls short compared to other technologies. Improving light extraction could significantly boost LEC efficiency. A diffuser film, comprising a transparent photoresist layer infused with both large and small TiO
2
nanoparticles (NPs) sandwiched between the indium-tin-oxide layer and the glass substrate, demonstrates remarkable light extraction capabilities. In this study, augmenting the concentration of small TiO
2
NPs was found to increase the thickness, roughness, and refractive index of the diffuser film. Optical simulations revealed that film thickness minimally impacts light extraction, whereas higher roughness coupled with a lower refractive index enhances light extraction. Therefore, an optimal concentration of small TiO
2
NPs is necessary to achieve the desired balance of roughness and refractive index for effective diffuser optimization. With the optimized concentration of small TiO
2
NPs, a substantial 2.5X improvement in light extraction and a high external quantum efficiency exceeding 30% can be attained.