Red‐Emitting Delayed Fluorescence and Room Temperature Phosphorescence from Core‐Substituted Naphthalene Diimides

Abstract

Unprecedented ambient triplet‐mediated emission in core‐substituted naphthalene diimide (cNDI) derivatives is unveiled via delayed fluorescence and room temperature phosphorescence. Carbazole core‐substituted cNDIs, with a donor–acceptor design, showed deep‐red triplet emission in solution processable films with high quantum yield. This study, with detailed theoretical calculations and time‐resolved emission experiments, enables new design insights into the triplet harvesting of cNDIs; an important family of molecules which has been, otherwise, extensively been investigated for its n‐type electronic character and tunable singlet fluorescence.

Application of time-resolved electron paramagnetic resonance spectroscopy in the mechanistic study of thermally activated delayed fluorescence (TADF) materials

“…[3][4][5][6]59,64 Any compounds with closely-lying 1 CT, 3 CT and 3 LE states may exhibit TADF properties (or more generally, close-lying S 1 /T 1 states). 65,66 Recently, we prepared a compact, orthogonal electron donor-acceptor dyad, with naphthalimide (NI) as the electron acceptor and phenothiazine (PTZ) as the electron donor (Fig. 6).…”

Arylene Diimide Phosphors: Aggregation Modulated Twin Room Temperature Phosphorescence from Pyromellitic Diimides

“…While arylene monoimides such as naphthalene monoimides and phthalimide derivatives are recently shown to exhibit ambient RTP, corresponding diimide derivatives are seldom exploited for triplet harvesting [8] . In this context, we have recently reported the ambient triplet harvesting of core‐substituted naphthalene diimides via RTP [4h] and thermally activated delayed fluorescence (TADF) [9] …”

Aromatic imide/amide-based organic small-molecule emitters for organic light-emitting diodes

“…(b) Phosphorescence properties may also be used for harvesting triplet excitons. Recent studies have shown that functionalized aromatic imides/amides can exhibit room-temperature phosphorescence by heavy atom substitution 61 or charge-transfer states, 62 and even exhibit transient and persistent mechanoluminescence at room temperature simultaneously which may be used to develop innovative applications in OLEDs. 61 (c) Combined with the AIE or AIDF effect, the PLQYs and EQEs of aromatic imide/amide-based emitters could be greatly improved to suppress the ACQ phenomenon.…”

“…(d) Lots of aromatic imide/amide optoelectronic materials are undeveloped as emitters in OLEDs, such as naphthalene diimide, 62 thieno [3,4-c]pyrrole-4,6-dione, 63,64 bithiophene imide (BTI), 65,66 and isoindigo. 67,68 BTI has the same heptagonal imide structure as BPI, thus serving as a promising building block of emitters.…”