Rational design of high efficiency green to deep red/near-infrared emitting materials based on isomeric donor-acceptor chromophores

A family of compounds TPA-BT-Q, TPA-pyT-N-naph, TPA-N-pyT-naph, and DPA-py-N-BT-naph with an isomeric donor-acceptor conjugation framework were designed and synthesized, and their structure-property relationships, theoretical calculations, and photophysical and electrochemical characteristics were investigated. These isomeric chromophores showed significantly different photophysical properties. Emission wavelengths spanning from the green to near-infrared region were observed in different solvents with high photoluminescence quantum yields, exceeding 90% in low polarity solvents and 44-88% in blend films. Organic light-emitting devices (OLEDs) displayed a strong electroluminescence with emission peaks at 592, 660, 630, and 580 nm; maximum current efficiencies of 7.92, 2.93, 3.56, and 15.37 cd A ⁻¹ ; maximum power efficiencies of 4.21, 1.56, 1.81, and 8.24 lm W ⁻¹ ; and maximum external quantum efficiencies of 3.15%, 2.75%, 2.66%, and 5.33% for TPA-BT-Q, TPA-pyT-N-naph, TPA-N-pyT-naph, and DPA-py-N-BT-naph doped OLEDs, respectively.