2026/01/27 by John Marques Dos Santos, Debasish Barman, Rangani Wathsala Weerasinghe +6 · 1 voice
Engineering · Materials Science · #Luminescence and Fluorescent Materials #Magnetism in coordination complexes #Organic Light-Emitting Diodes Research
paper · pdf · doi:10.26434/chemrxiv.10001623/v1
openalex publication_date 2026/01/27 · openalex created_date 2026/01/28 · openalex updated_date 2026/07/14
Two new multiresonant thermally activated delayed fluorescence (MR-TADF) emitters, BINAP-BN1 and BINAP-BN2, containing a 1,1'-binaphthalene (BINAP) unit and a varying number of tCzBN units (one in BINAP-BN1 and two in BINAP-BN2), were synthesized. In toluene, both showed emission maxima at ca. 490 nm, photoluminescence quantum yields (Φ PL ) up to 82%, and Δ E ST of ~0.15 eV. Significant differences in their optoelectronic properties emerged as their 1 wt% doped films in mCBP. BINAP-BN1 has a Φ PL of 82%, while that of BINAP-BN2 is 64%. Aggregation-induced emission broadening at higher doping concentrations is suppressed for BINAP-BN1 but not for BINAP-BN2, attributed to the less sterically hindered BINAP moiety in the former. These photophysical differences translated in device performance. The organic light-emitting diodes (OLEDs) with BINAP-BN1 and BINAP-BN2 achieved maximum external quantum efficiencies (EQE max ) of 20.1 and 14.1%, respectively, at corresponding CIE coordinates of (0.08, 0.42) and (0.10, 0.50). A hyperfluorescence (HF) device employing HDT-1 as sensitizer and BINAP-BN1 as terminal emitter improved EQE max to 22.0% and reduced efficiency roll-off to 32% at 1000 cd/m², compared to 52% in the binary device. In comparison, a device with 1 wt% tCzBN in mCBP showed an EQE max of 15.6%, rising to 21.6% in a HF configuration.