Excited-State Descriptors for High-Throughput Screening of Efficient Electro-Fluorescent Materials

Electro-fluorescent materials with 100% internal quantum
efficiency
(IQE) and short fluorescence lifetimes (τf, ∼
ns) are desirable and achievable by harvesting high-lying triplet
excitons. However, the IQE governed by exciton utilization efficiency
(EUE) and photoluminescence quantum yield (PLQY) remains low. Herein,
from the electro-fluorescence process involving triplet excitons and
energy gap law, we established two excited-state descriptors (triplet–triplet
energy gap ΔETT and oscillator strength f) to characterize EUE, PLQY and τf, by
taking a series of hot exciton compounds as prototypes. Subsequently,
these descriptors were employed to perform high-throughput screening
of over 5000 fluorophores, predicting 19 candidate molecules with
a high IQE (>90%). We stressed that the large values of these descriptors
are conducive to high EUE and PLQY and short τf.
This work presents a guideline to design and screen efficient electro-fluorescent
materials beyond the spin-statistical limit.