Regulating Spatial Configuration in Donor‐π‐Acceptor for through‐Space Exciton Transfer: Concentration‐Independent Emitter for OLEDs
Year: 2024
Type: article
Abstract: Thermally activated delayed fluorescence (TADF) emitters have garnered much attention due to 100% exciton utilization and toxic metal‐free design but often experience concentration‐quenching, requiring dispersion into the host matrix. Developing emitters that maintain consistent performance and emission wavelength irrespective of the concentration remains a significant challenge. Herein, two TADF emitters (2BPy‐pTC and 2BPy‐oTC) are designed and synthesized. The nature and energetics of the lowest excited singlet (S1) and triplet (T1) along with the extent of through‐bond exciton transfer (TBET) and through‐space exciton transfer (TSET) are unveiled using reliable quantum‐chemical calculations. While 2BPy‐pTC exhibits pre‐dominantly TBET, a greater extent of TSET is found in 2BPy‐oTC. Both emitters show a low singlet‐triplet energy gap (ΔEST), 0.21 eV for 2BPy‐pTC and 0.02 eV for 2BPy‐oTC. For 2BPy‐pTC, increasing the emitter concentration from 5 to 100 wt.% causes a bathochromic shift in the electroluminescence (EL) peak (467 to 495 nm) and a drop in maximum external quantum efficiency (EQEmax) from 12.0% to 5.5%. In contrast, 2BPy‐oTC maintains EL maxima of 500 nm and consistent EQEmax (24.0% – 27.2%) while increasing emitter concentration, acting as a universal emitter for both doped and non‐doped OLEDs and eliminating the need for tedious co‐deposition.
Source: Advanced Optical Materials
Language: English
Subfield: Electrical and Electronic Engineering
Field: Engineering
Domain: Physical Sciences
Open Access status: bronze
Awards: G1907199259, G2262632074, G2370302201
OpenAlex ID: W4405796414