Mapping the Chemical Space of TADF Sensitizers Coupled with Virtual Screening for Narrowband Hyperfluorescence OLEDs

Developing efficient thermally activated delayed fluorescence (TADF) sensitizers for narrowband red hyperfluorescence organic light-emitting diodes (HF-OLEDs) remains a major challenge because long-wavelength sensitization requires the simultaneous optimization of a small singlet-triplet energy gap (ΔEST), a low singlet excited-state energy (ES1), and a high solid-state photoluminescence quantum yield (ΦPL). Unlike their successful blue and green counterparts, red HF-OLEDs are still largely reliant on noble-metal phosphorescent sensitizers. Here, we establish a donor-acceptor-linker chemical-space mapping framework coupled with virtual screening to enable the rapid discovery of metal-free TADF sensitizers suitable for narrowband red HF-OLEDs while circumventing conventional iterative trial-and-error molecular optimization. Screening a virtual library of 160 molecular architectures identifies linker topology, rather than donor-acceptor identity alone, as the key structural determinant of excited-state energetics, with the 1,8-disubstituted naphthalene scaffold emerging as a privileged motif that simultaneously minimizes ΔEST and ES1. Guided by these insights, a gram-scalable modular synthesis furnishes a family of peri-naphthalene-based, spatially confined through-space charge-transfer (TSCT) TADF sensitizers exhibiting emission maxima reaching 667 nm, ultralow ΔEST values below 0.01 eV, and solid-state ΦPL values of up to 98% through aggregation-induced emission (AIE). When paired with all-carbon polycyclic aromatic hydrocarbon (PAH) emitters, these sensitizers deliver narrowband red HF-OLEDs with a maximum external quantum efficiency (EQE) of 27.6%, setting a benchmark for all-carbon PAH-based red HF-OLEDs. Moreover, the same TSCT platform is readily extendable to shorter-wavelength systems, as demonstrated by yellow PAH-based HF-OLEDs with an outstanding maximum EQE of 27.7%.