Enhanced Electroluminescence from a Thiophene-Based Insulated Molecular Wire

We report on the realization of polymer light-emitting diodes (PLEDs) based on fluorescent polythiophene (PT)-based insulated molecular wires (IMWs). PLEDs using PT emitting layers traditionally have low external quantum efficiencies (ηeqe) below 0.1%. Moreover, IMWs lack a thorough exploitation for electroluminescent applications due to concerns about reduced charge transport between their chains. We constructed multilayer PLEDs containing PT IMW emitting layers that show the maximum ηeqe close to 1.4%, luminance at 3700 cd/m2, and low turn on voltage at 2.5 V. We also show a strong influence of the thickness of electron transport layer on ηeqe through device optimization and optical simulations.