Quantum-Sized SnO₂ Nanoparticles with Upshifted Conduction Band: A Promising Electron Transportation Material for Quantum Dot Light-Emitting Diodes

In previous reports of the literature, ZnO nanoparticles were unexceptionally used as the electron transportation material in highly efficient CdSe-based quantum dot light-emitting diodes (QD-LEDs). However, as an amphoteric oxide, ZnO nanoparticles are chemically unstable in air. Here, we utilize quantum-sized SnO₂ nanoparticles as the electron transportation layer (ETL) of CdSe-based QD-LEDs. Decreasing the size of SnO₂ nanoparticles will upshift the conduction band from −4.50 to −3.84 eV based on the quantum size effect, which is beneficial to facilitate electron injection into the QD emitting layer. Our investigations show that QD-LEDs based on quantum-sized SnO₂ nanoparticles exhibit comparable electroluminescence properties and higher stability in contrast to ZnO nanoparticle-based QD-LEDs, demonstrating that small-sized SnO₂ nanoparticles have a bright prospect due to the ETL in QD-LEDs.