Electronic Level Alignment at an Indium Tin Oxide/PbI Interface and Its Applications for Organic Electronic Devices.

The electronic level alignment at the indium tin oxide (ITO)/PbI interface is investigated by an ultraviolet photoelectron spectroscopy. An n-type conductivity property is found for PbI as well as a downward shift energy level at the ITO/PbI interface. These indicate that PbI can be used as an anode buffer layer for organic electronic devices. The power conversion efficiency of the organic solar cell based on tetraphenyldibenzoperiflanthene/C planar heterojunction is dramatically increased from 1.05 to 3.82%. Meanwhile, the thermally activated delayed fluorescence organic light-emitting diode based on 4,4',4″-tri( N-carbazolyl)triphenylamine-((1,3,5-triazine-2,4,6-triyl)tris(benzene-3,1-diyl))tris(diphenylphosphine oxide) shows a significantly reduced turn-on voltage and enhanced power efficiency from 6.26 to 18.60 lm/W. The improved performance is attributed to the high hole injection/extraction efficiency at the ITO/PbI interface. Besides, the near-infrared (NIR) absorption of lead phthalocyanine (PbPc)-based NIR organic photodetector (NIR-OPD) is dramatically increased, indicating that the PbI layer can also be used as a template layer for the growth of the triclinic phase of PbPc. As a result, the optimized device shows an external quantum efficiency of 26.7% and a detectivity of 9.96 × 10 jones at 900 nm, which are among the highest ones reported for organic NIR-OPDs.