Controlling Organic Room Temperature Phosphorescence through External Heavy‐Atom Effect for White Light Emission and Luminescence Printing

Abstract

Pure organic materials with tunable room temperature phosphorescence (RTP) have attracted considerable interest because they are promising candidates for a wide range of optoelectronic applications. Herein, a series of organic compounds of (4‐(9H‐carbazol‐9‐yl)butyl) triphenylphosphonium (CBTP) with different halide anions (CBTP‐Cl, CBTP‐Br, and CBTP‐I) are synthesized. They show emission color changes from blue to orange‐red in the solid state. Single‐crystal X‐ray diffraction analysis and theoretical calculations demonstrate that the RTP is primarily caused by the external heavy‐atom effect (EHE), which enhances the spin–orbit coupling between the singlet and triplet excited states to facilitate the intersystem crossing rate. Distinct white light emission can be achieved using the controllable RTP by doping a certain ratio of potassium iodide (KI) into a polymer matrix containing CBTP‐Cl. Moreover, luminescent information can be recorded on a paper substrate made from a polymer film containing CBTP‐Cl with KI aqueous solution as the ink. The results suggest that rational control of the EHE of these pure organic materials is promising for different optoelectronic applications, including solid‐state lighting, data recording, and security protection.

Boosting purely organic room-temperature phosphorescence performance through a host–guest strategy

“…[18][19][20] Currently, crystallization-induced phosphorescence is of the greatest concern in developing efficient RTP systems, including singlecomponent molecular crystal and host-guest cocrystal. [21][22][23][24][25][26] In solid states, a variety of single-component RTP materials have been successfully established, composed of some traditional organic functional groups, such as carbazole, 23,27,28 halogen elements, 29,30 aromatic carbonyl groups and so on. 3,22,31 Compared with these single-component RTP materials, hostguest chemistry has received a flurry of increasing attention because of its ability to boost phosphorescence performance through some distinctive characters of the host matrix.…”

Ambient White-Light Afterglow Emission Based on Triplet-to-Singlet Förster Resonance Energy Transfer

“…As a kind of visible light, white-light emission usually requires a combination of three primary colors at certain proportions or two complementary ones, which has significant application value in the fields of lighting, sensors, and display. [21][22][23][24][25] Superior to inorganic afterglow materials with white-light emission, organic counterparts are preferred due to fine-tuning, solution processability, low toxicity and cost, and simpler fabrication. [26][27][28][29] The demands in practical applications have facilitated the construction of versatile organic afterglow materials with both emission tunability and high quantum yield.…”

Time-Dependent Afterglow from a Single Component Organic Luminogen

“…For example, Huang and An et al obtained dual phosphorescent emission from monomers and H-aggregates of triazine derivatives with excitation-dependent color-tunable p-RTP, which renders them applicable in UV detection [ 18 ]. Currently, the PL color tunability is mostly achieved by modifying the molecular structures [ 27 ], achieving polymorphs [ 23 , 28 ], changing the temperature or the excitation wavelength ( λ ex ) [ 18 , 22 , 29 , 30 ], and so on [ 31 – 33 ]. Organics with time-dependent color-tunable afterglow, however, are rarely reported [ 14 , 34 ], especially for single-component materials.…”