Self‐Assembled Helical Arrays for the Stabilization of the Triplet State

Abstract

Room‐temperature phosphorescence of metal and heavy atom‐free organic molecules has emerged as an area of great potential in recent years. A rational design played a critical role in controlling the molecular ordering to impart efficient intersystem crossing and stabilize the triplet state to achieve room‐temperature ultralong phosphorescence. However, in most cases, the strategies to strengthen phosphorescence efficiency have resulted in a reduced lifetime, and the available nearly degenerate singlet‐triplet energy levels impart a natural competition between delayed fluorescence and phosphorescence, with the former one having the advantage. Herein, an organic helical assembly supports the exhibition of an ultralong phosphorescence lifetime. In contrary to other molecules, 3,6‐phenylmethanone functionalized 9‐hexylcarbazole exhibits a remarkable improvement in phosphorescence lifetime (>4.1 s) and quantum yield (11 %) owing to an efficient molecular packing in the crystal state. A right‐handed helical molecular array act as a trap and exhibits triplet exciton migration to support the exceptionally longer phosphorescence lifetime.

Efficient metal-free organic room temperature phosphors

“…The importance of exciton diffusion length is more dominant in the case of crystalline arrays with more traps. However, a very recent demonstration indicated that the triplet exciton diffusion with the assistance of helical arrays of phosphor played an essential role in delaying the triplet radiative decay to extend lifetime beyond 4 s. 45 Hence the quality of the generated crystals or thin films and management of triplet excitons can impart excellent RTP features. More studies in this direction are required for detailed understanding and further development.…”

“…5 ). 45 An N -alkylated carbazole decorated with phenylmethanone units PCz ( Fig. 5a ) exhibited URTP with high efficiency ( τ p > 4.1 s and ϕ p of 11%) ( Fig.…”

“… 123–125 Another area that can be explored is the nonlinear optical properties of RTP materials, which will bring out newer concepts in demonstrations. Even though a few attempts have been made with lasing 126 and waveguiding 45 applications of ORTPs, more detailed studies are envisioned for RTP materials.…”

Stimuli‐Responsive Deep‐Blue Organic Ultralong Phosphorescence with Lifetime over 5 s for Reversible Water‐Jet Anti‐Counterfeiting Printing

“…These OURTP performance are among the best results ever reported in organic afterglow materials (Supporting Information, Table S1). [27][28][29][30] To take advantage of the extraordinary water-responsive OURTP feature,s ecret data storage and pattern anti-counterfeiting were facilely achieved by water-jet printing on the waterresponsive OURTP paper using ac ommercial jet printer simply by replacing the ink with water without any other adjustments.T he water printed high-resolution patterns are invisible under daylight and UV light, but can only be easily captured by camera and naked eyes after removing the 254 nm UV excitation. Particularly,t he water-promoted OURTP pattern is very stable that can last for weeks but can be easily erased by dimethyl sulfoxide (DMSO) fuming in minutes;this enables the reversible write and erase character of the water-responsive OURTP paper that can be reused for many printing/erasing cycles.T he highly efficient anti-counterfeiting rewritable paper by combining the water-responsive character and organic afterglow feature together illustrates apromising approach to realize stimulus-responsive OURTP and reversible water-jet anti-counterfeiting printing through boron phosphor doping and H-bonding network tuning of the host-guest materials.…”

One-axis Two-wing Guest-Host Strategy for Constructing Ultralong-lifetime Near-infrared Organic Phosphorescence Materials for Bioimaging

“…[10][11][12][13][14][15] To date, most phosphorescent materials have poor biological tissue permeability because the wavelengths of their emission spectra are short (less than 580 nm). [16][17][18][19][20][21][22][23][24][25][26][27] This only means phosphors provide good imaging in shallow regions of an organism. Constructing near-infrared phosphorescent materials has gained some urgency.…”