Phosphor-Assisted TADF-Sensitized Fluorescence (pTSF) OLEDs: Faster Excitons, Brighter Futures

The impressive efficiency and lifetime under ultrahigh luminance remain a long-standing challenge for organic light-emitting diodes (OLEDs), as conventional fluorescent, phosphorescent, and thermally activated delayed fluorescent (TADF) systems universally suffer from accelerated bimolecular annihilation at elevated exciton densities. Recently, phosphor-assisted TADF-sensitized fluorescence (pTSF) has emerged as a groundbreaking architecture that synergistically integrates exciton utilization enhancement and radiative decay acceleration through breaking the singlet-triplet spin-flip cycles in thermally activated delayed fluorescence (TADF) hosts via multiple sensitizations. The OLEDs based on pTSF achieve not only a nearly roll-off-free on external quantum efficiency but also a remarkable power efficiency, even when operating at ultrahigh luminance levels exceeding 100,000 cd m^-2. In this review, we delve into the intricacies of pTSF technology, examining its material design principles, energy transfer dynamics, and exciton management processes. Eventually, we critically assess the challenges in implementing pTSF for blue-emitting OLEDs and propose strategic research directions to harness the full potential of this transformative technology.