Overcoming the Absorption Bottleneck for Solid-State Infrared-to-Visible Upconversion

Upconversion (UC) of near-infrared photons into visible photons can revolutionize state-of-the-art technologies in photovoltaics, night vision, anti-counterfeiting, photodetectors, and beyond. However, current solid-state triplet-triplet annihilation UC devices that rely on PbS quantum dots and organic semiconductor annihilators suffer from low absorption, low energy transfer rates, and highly parasitic back transfer processes which lead to low external quantum efficiencies (EQE). Here, we propose a device architecture which mitigates FRET-based back transfer to improve the EQE. We demonstrate the use of 5-tetracene carboxylic acid (TCA) as a ligand and blocker layer to drastically improve EQEs. Finally, the mechanism of improvement is deconvolved through spectroscopic studies of the system.