A study of tin oxide as an election injection layer in hybrid polymer light-emitting diodes

We investigate the n-type metal oxide Tin (IV) oxide (SnO2), as an electron injection and transport layer in hybrid polymer light-emitting diodes (HyLEDs). SnO2 is air stable and bio-safe, with high optical transparency and electrical conductivity, and with a deep valence band energy, making it highly suitable for such applications. Results reveal that SnO2 is effective as an electron injecting cathode material, when a thin hole-blocking interlayer of Cs2CO3 or Ba(OH)2 is coated on it. Devices are optimized with respect to injection-layer thickness and hole-blocking layer configuration, with high performance metrics (current efficiencies of 20 cd/A, external quantum efficiencies of 6.5%) being demonstrated in the device with Ba(OH)2 as the inorganic interlayer in the hybrid architecture. Also, we characterize thin-films of spray-pyrolysis deposited SnO2, as compared with the commonly used interlayer material ZnO, in terms of film morphology and interfacial photophysics. Doucment embargo 28/10/2015.