Phosphorescence Quantum Yield Research Articles

Controlling the Triplet Potential Energy Surface of Bimetallic Platinum(II) Complex by Constructing Structure-Property Relationship: A Theoretical Exploration.

For phosphorescent materials, managing the triplet potential energy surface stands for controlling the phosphorescence quantum yield. However, due to the complexity and variability, the triplet potential energy surface can be managed with difficulty. In this work, a series of bimetallic Pt(II) complexes, namely Pt-1, Pt-1-1, Pt-1-2, Pt-2, Pt-3-5, and Pt-6-7, are employed as models to construct a relationship between the structures and triplet potential energy surfaces, aiming to achieve meaningful information to manage the triplet potential energy surface. On the basis of the results, it is observed that the triplet potential energy surface has an intimate connection with the structures of bimetallic Pt(II) complexes. In the case of the primordial Pt(II) complex, the triplet potential energy surface consists of two minimal points, illustrating various properties, which can largely affect the phosphorescence quantum yield. Once the intramolecular steric hindrance, restriction effect, and metallophilic interaction (Pt-Pd/Pd-Pd) are employed by tailoring the structures of primordial Pt(II) complexes, the triplet potential energy surface can be reconstructed via one minimal point-charactered short metal-metal distance, resulting in different photophysical properties. The relationship between the triplet potential energy surface and structure is essentially unveiled from the structural and electronic viewpoints. The conclusions originated from the structural and electronic investigations can be regarded as indicators to accurately and expediently predict the triplet potential energy surfaces of bimetallic Pt(II) complexes. The results presented here are helpful in addressing the designed strategies as they show that the triplet potential energy surfaces of bimetallic Pt(II) complexes can be properly tuned.

High Color Stability Blue-to-Violet Room Temperature Phosphorescent Carbon Dot Composites with Ultralong Lifetime for Information Encryption

Ultralong room temperature phosphorescent (RTP) materials have a wide range of applications in information encryption, bio-imaging, optoelectronics, and display and illumination. Among them, blue-emitting RTP materials with high quantum yield (QY) and ultralong luminescence have been a challenge in the field of RTP materials. Herein, we prepared blue-to-violet RTP carbon dot (CD) composites with high color stability by mixing boric acid with pyromellitic acid, trimesic acid, and terephthalic acid, separately, and pyrolyzing them at identical temperature conditions, leading to CD composites with emission peaks at 440, 407, and 430 nm, respectively. This strategy enables the precursors to effectively suppress the deactivation of the triplet state through covalent bonding (B–C bond) and hydrogen bonding interactions and confinement in a highly rigid B2O3 polycrystalline network, thereby successfully producing blue-to-violet CD composites with high QY (49, 64, and 78%, meanwhile, their phosphorescence QY can reach 47, 57, and 65%), ultralong lifetime (0.633, 1.882, and 2.332 s, respectively), and high color stability. Owing to the unique properties, the CD composites show great potential for application in the field of anti-counterfeiting and information encryption.

Switchable and Highly Robust Ultralong Room‐Temperature Phosphorescence from Polymer‐Based Transparent Films with Three‐Dimensional Covalent Networks for Erasable Light Printing

AbstractIn this work, an efficient polymer‐based organic afterglow system, which shows reversible photochromism, switchable ultralong organic phosphorescence (UOP), and prominent water and chemical resistance simultaneously, has been developed for the first time. By doping phenoxazine (PXZ) and 10‐ethyl‐10H‐phenoxazine (PXZEt) into epoxy polymers, the resulting PXZ@EP‐0.25 % and PXZEt@EP‐0.25 % films show unique photoactivated UOP properties, with phosphorescence quantum yields and lifetimes up to 10.8 % and 845 ms, respectively. It is found that the steady‐state luminescence and UOP of PXZ@EP‐0.25 % are switchable by light irradiation and thermal annealing. Moreover, the doped films can still produce conspicuous UOP after soaking in water, strong acid and base, and organic solvents for more than two weeks, exhibiting outstanding water and chemical resistance. Inspired by these exciting results, the PXZ@EP‐0.25 % has been successfully exploited as an erasable transparent film for light printing.

Switchable and Highly Robust Ultralong Room-Temperature Phosphorescence from Polymer-Based Transparent Films with Three-Dimensional Covalent Networks for Erasable Light Printing.

In this work, an efficient polymer-based organic afterglow system, which shows reversible photochromism, switchable ultralong organic phosphorescence (UOP), and prominent water and chemical resistance simultaneously, has been developed for the first time. By doping phenoxazine (PXZ) and 10-ethyl-10H-phenoxazine (PXZEt) into epoxy polymers, the resulting PXZ@EP-0.25% and PXZEt@EP-0.25% films show unique photoactivated UOP properties, with phosphorescence quantum yields and lifetimes up to 10.8% and 845 ms, respectively. It is found that the steady-state luminescence and UOP of PXZ@EP-0.25% are switchable by light irradiation and thermal annealing. Moreover, the doped films can still produce conspicuous UOP after soaking in water, strong acid and base, and organic solvents for more than two weeks, exhibiting outstanding water and chemical resistance. Inspired by these exciting results, the PXZ@EP-0.25% has been successfully exploited as an erasable transparent film for light printing.

Ultralong Room-Temperature Phosphorescence of Boron Carbon Oxynitride Nanodots Encapsulated in Pyrophosphate in Dry and Wet States for Fingerprint Detection and Information Protection

Room-temperature phosphorescence (RTP) materials have attracted wide interest due to their long lifetime and free from background autofluorescence. Nevertheless, simultaneous activation of stable long-lived RTP emission in both solid and aqueous phases remains a tremendous challenge. Herein, a molten salt method to synthesize boron carbon oxynitride nanodot-based RTP composites (BCNO nanodots@pyrophosphate) was carried out by employing pyrophosphate as the inert shell for BCNO nanodots. The BCNO nanodots@pyrophosphate1 with the average size of 3.69 nm show bright-green RTP because the introduction of phosphorus is beneficial to the intersystem crossing process and increases the RTP emission. What is more, whether in solid or aqueous dispersion, BCNO nanodots@pyrophosphate1 retains good phosphorescent properties with a high phosphorescence quantum yield (29.5% and 18.6%) and a long lifetime (1.39 and 1.29 s), which lasts over 15 s to the naked eye. This is the first report on BCNO nanodots with RTP in aqueous solution. The unique RTP characteristics allow BCNO nanodots@pyrophosphate as a hopeful indicator for detection of latent fingerprints with high contrast and multilevel information protection.

Unveiling the influence of the various-membered ring structures on the performance of Ir(iii) complexes: phosphorescent quantum yields and stabilities

For the heteroleptic Ir(iii) complexes, unveiling the role of ancillary ligands is significant for designing excellent phosphorescent materials.

Controlling the efficient and ultralong room-temperature phosphorescence of 9H-dibenzo[a,c]carbazole derivatives for erasable light printing

Two polymer systems containing 9H-dibenzo[a,c]carbazole derivatives showed phosphorescence quantum yields and lifetimes of up to 13.5% and 3.01 s after photoactivation.

Modulating room temperature phosphorescence through intermolecular halogen bonding

Room temperature phosphorescence materials based on halogenated-morpholine are obtained, wherein the halogen bonding is directly involved in the acceleration of the intersystem crossing and enhancement of solid-state phosphorescence quantum yield.

New Phthalic Anhydride‐Based Room‐Temperature Phosphorescence Emitter with Lifetime Longer Than One Second

AbstractOrganic room‐temperature phosphorescence (RTP) materials have attracted much attention in recent years due to their potential applications. However, the development of organic RTP emitters with a long lifetime and high quantum yield remains a great challenge owing to the weak molecular spin–orbit coupling and high sensitivity to oxygen. In this paper, a new purely organic RTP emitter, 3,3″,4,4″‐diphenylsulfonetetracarboxylic dianhydride (DPS), is reported which shows an excitingly ultralong lifetime up to 1.08 s and high phosphorescence quantum yield of 8%. When anhydride units in DPS are transformed into imides, the RTP performance in terms of lifetime and quantum yield is decreased. The presence of multiple intermolecular interactions is favorable for the restriction of nonradiative decay and the promotion of spin–orbit coupling, which is further corroborated by theoretical calculations. The studies demonstrate that DPS is a promising structural motif for developing high‐performance organic RTP emitters.

Ir(III) phosphorescent complexes with the ligands attaching pyridyl group to 4-position of dibenzo[b,d]thiophene-S,S-dioxide/dibenzo[b,d]thiophene unit and their efficient solution-processed OLEDs

Through attaching pyridyl ring to 4-position of dibenzo[b,d]thiophene-S,S-dioxide and dibenzo[b,d]thiophene, two ppy-type ligands have been developed. With the obtained ligands in one-pot reaction, three Ir(III) complexes have been synthesized as symmetric Ir-1 with two dibenzo[b,d]thiophene-S,S-dioxide units, unsymmetric Ir-2 with both dibenzo[b,d]thiophene-S,S-dioxide and dibenzo[b,d]thiophene units and symmetric Ir-3 with two dibenzo[b,d]thiophene units. Photophysical results show that their phosphorescent wavelengths fall in the order of Ir-2 (585 nm) ˃ Ir-1 (567 nm) ˃ Ir-3 (543 nm) in solution and their phosphorescent quantum yields (Φp) fall in the same order with ca. 0.83 for Ir-2, 0.68 for Ir-1 and 0.53 for Ir-3, indicating the advantage of constructing unsymmetric Ir(III) complexes. Solution-processed OLEDs based on the unsymmetric complex Ir-2 can show the highest electroluminescent (EL) efficiencies with the external quantum efficiency (ηext) of 16.6%, a maximum current efficiency (ηL) of 51.1 cd A − 1 and a maximum power efficiency (ηP) of 38.7 lm W − 1, indicating its great potential in the EL field. These encouraging results can provide critical information for developing highly efficient phosphorescent emitters based on dibenzo[b,d]thiophene-S,S-dioxide and dibenzo[b,d]thiophene groups.

A new mode of luminescence in lanthanide oxalates metal–organic frameworks

Two lanthanide metal–organic frameworks [Ln-MOFs, Ln = Eu(III), Tb(III)] composed of oxalic acid and Ln building units were hydrothermally synthesized and fully characterized by powder X-ray diffraction, Fourier-transform infrared spectroscopy, thermogravimetric analysis, scanning electron microscope, and energy-dispersive X-ray spectroscopy. Furthermore, their magnetic susceptibility measurements were obtained using SQUID based vibrating sample magnetometer (MPMS 3, Quantum Design). Both Ln-MOFs exhibited highly efficient luminescent property. Solid-state photoluminescence (PL) measurements revealed phosphorescence emission bands of Eu-MOF and Tb-MOF centered at 618 nm (red emission) and 550 nm (green emission) upon excitation at 396 nm and 285 nm, respectively. Eu-MOF and Tb-MOF displayed a phosphorescence quantum yield of 53% and 40%, respectively. Time-resolved PL analyses showed very long lifetime values, at 600 and 1065 ± 1 µs for Eu-MOF and Tb-MOF, respectively. Calculations performed by density functional theory indicated a charge transfer form metal centres to the ligand which was in good agreement with the experimental studies. Therefore, this new mode of highly photoluminescent MOF materials is studied for the first time which paves the way for better understanding of these systems for potential applications.

Organic Phosphorescence Lasing Based on a Thermally Activated Delayed Fluorescence Emitter.

Organic phosphorescence materials provide an opportunity to use triplets for lasing. However, population inversion based on phosphorescence is hard to establish, owing to low luminescent quantum efficiency and intensive optical loss. By comparison, thermally activated delayed fluorescence emitters exhibit excellent optical gain with the aid of the reverse intersystem crossing (RISC) process. In this work, we designed a multifunctional gain material, not only serving as a thermally activated delayed fluorescence (TADF) emitter with excellent optical gain but also working as a phosphorescence source with high utilization of triplets. The lone pair of electrons in oxygen substitutions promotes a fast spin-flip and high delayed fluorescence quantum yield (ΦDF = 55%), enabling TADF amplified spontaneous emissions (ASE) of CH2Cl2 solution. Single-crystalline nanowires of H-aggregates effectively lower triplet energy levels with high phosphorescence quantum yield (ΦP = 27%), demonstrating Fabry-Perot mode phosphorescence lasing at 630 nm.

Distinguishing the Quantum Yield and Lifetime of Carbazole‐Based Room‐Temperature Phosphorescence Materials: QM/MM Study

AbstractCommercial carbazole derivatives are widely used as typical electron donors in room‐temperature phosphorescence materials. The high phosphorescence quantum yield (Φp) and short lifetime (τp) of the carbazole‐based (9H‐carbazol‐9‐yl)isonicotinonitrile (P‐34N) crystal are distinguished by quantum mechanics and molecular mechanics method. Two inducements are accounted for the high Φp of P‐34N: i) large spin–orbit coupling (0.63 cm−1) induces fast intersystem crossing (ISC) of the lowest singlet excited state (S1) to the lowest triplet excited state (T1), ii) the intermolecular π–π interactions stabilize triplet excitons. Meanwhile, the 3(n, π*) →1(π, π*) of P‐34N favors the nonradiative decay of T1to the ground state (S0), and thus, causes short τp. In contrast to P‐34N, the low Φp of 6‐(9H‐carbazol‐9‐yl)nicotinonitrile (P‐24N) crystal results from the effective reverse ISC process induced by small ΔEST (0.3 eV) between S1 state and the higher triplet state (T2), and the long τp is due to the unfavorable orbital reversals of T1 (π, π*)→S0 (π, π*) transition and the internal conversion process of T2 → T1. This work presents a reasonable interpretation of the Φp and τp of two carbazole‐based crystals.

Achieving Color‐Tunable and Time‐Dependent Organic Long Persistent Luminescence via Phosphorescence Energy Transfer for Advanced Anti‐Counterfeiting

AbstractOrganic ultralong room‐temperature phosphorescence (RTP) materials have promising applications in anti‐counterfeiting. To improve the encryption level, the exploration of organic materials with tunable solid‐state long persistent luminescence is in urgent need. Herein, a series of organic ultralong RTP polymeric systems are prepared by doping versatile indolocarbazole isomers into the poly(vinyl alcohol) (PVA) matrix. Notably, the doping film 11,12‐ICz@PVA exhibits excellent RTP property with an ultralong lifetime of 2.04 s and a high phosphorescence quantum yield of 44.1%. Theoretical calculations reveal that this excellent RTP property can be attributed to the strong electrostatic attraction resulting from the synergistic double hydrogen‐bond between the isomer 11,12‐ICz and PVA matrix. More impressively, color‐tunable and time‐dependent long persistent luminescence is successfully achieved through efficient phosphorescence energy transfer between the indolocarbazole isomers with ultralong blue RTP emissions and commercially available fluorescent dyes with emission colors ranging from green to red doped into the PVA matrix. Besides, diversified encryption patterns are fabricated to demonstrate the promising applications of these water‐soluble doping PVA systems with tunable solid‐state persistent luminescence in advanced anti‐counterfeiting technology.

Efficient room-temperature phosphorescence of covalent organic frameworks through covalent halogen doping.

Organic room-temperature phosphorescence, a spin-forbidden radiative process, has emerged as an interesting but rare phenomenon with multiple potential applications in optoelectronic devices, biosensing and anticounterfeiting. Covalent organic frameworks (COFs) with accessible nanoscale porosity and precisely engineered topology can offer unique benefits in the design of phosphorescent materials, but these are presently unexplored. Here, we report an approach of covalent doping, whereby a COF is synthesized by copolymerization of halogenated and unsubstituted phenyldiboronic acids, allowing for random distribution of functionalized units at varying ratios, yielding highly phosphorescent COFs. Such controlled halogen doping enhances the intersystem crossing while minimizing triplet-triplet annihilation by diluting the phosphors. The rigidity of the COF suppresses vibrational relaxation and allows a high phosphorescence quantum yield (ΦPhos ≤ 29%) at room temperature. The permanent porosity of the COFs and the combination of the singlet and triplet emitting channels enable a highly efficient COF-based oxygen sensor, with an ultra-wide dynamic detection range (~103-10-5 torr of partial oxygen pressure).

Recent Advances in Organic Room-Temperature Phosphorescence of Heteroatom (B/S/P)-Containing Chromophores

Recent Advances in Organic Room-Temperature Phosphorescence of Heteroatom (B/S/P)-Containing Chromophores

Nanocluster Transformation Induced by SbF6- Anions toward Boosting Photochemical Activities.

The interactions between SbF6- and metal nanoclusters are of significance for customizing clusters from both structure and property aspects; however, the whole-segment monitoring of this customization remains challenging. In this work, by controlling the amount of introduced SbF6- anions, the step-by-step nanocluster evolutions from [Pt1Ag28(S-Adm)18(PPh3)4]Cl2 (Pt1Ag28-Cl) to [Pt1Ag28(S-Adm)18(PPh3)4](SbF6)2 (Pt1Ag28-SbF6) and then to [Pt1Ag30Cl1(S-Adm)18(PPh3)3](SbF6)3 (Pt1Ag30-SbF6) have been mapped out with X-ray crystallography, with which atomic-level SbF6- counterion effects in reconstructing and rearranging nanoclusters are determined. The structure-dependent optical properties, including optical absorption, photoluminescence, and electrochemiluminescence (ECL), of these nanoclusters are then explored. Notably, the Pt1Ag30-SbF6 nanocluster was ultrabright with a high phosphorescence quantum yield of 85% in N2-purged solutions, while Pt1Ag28 nanoclusters were fluorescent with weaker emission intensities. Furthermore, Pt1Ag30-SbF6 displayed superior ECL efficiency over Pt1Ag28-SbF6, which was rationalized by its increased effectively exposed reactive facets. Both Pt1Ag30-SbF6 and Pt1Ag28-SbF6 demonstrated unprecedented high absolute ECL quantum efficiencies at sub-micromolar concentrations. This work is of great significance for revealing the SbF6- counterion effects on the control of both structures and luminescent properties.

Highly Emissive Luminogens in Both Solution and Aggregate States

Highly Emissive Luminogens in Both Solution and Aggregate States

Defects and Structural Limitation-Induced Carbon Dots-Silica Hybrid Materials with Ultralong Room Temperature Phosphorescence.

Carbon dots-based room temperature phosphorescent (RTP) materials have attracted widespread attention owing to their excellent optical properties. However, there still is a challenge to fabricate carbon dots-based materials simultaneously showing long RTP lifetime and high phosphorescent quantum yield. Herein, we have designed a kind of carbon dots-silica hybrid material that can produce RTP emission with ultralong lifetime and also high phosphorescent quantum yield (1.3 s and 11.22%). Both chemical and optical analytical characterizations indicate the source of the outstanding RTP performance as the synergistic strategy of abundant electron traps, highly rigid network, and stable covalent bond. The findings provide a new design idea to achieve novel carbon dots-based RTP materials, showing broad application prospects in optical anticounterfeiting, optoelectronics, and others.

Generation of Tunable Ultrastrong White‐Light Emission by Activation of a Solid Supramolecule through Bromonaphthylpyridinium Polymerization

AbstractHerein, we reported solid supramolecular bromonaphthylpyridinium polymers (P‐BrNp), which exhibit tunable phosphorescence emission in the amorphous state enabled by sulfobutylether‐β‐cyclodextrin (SBE‐β‐CD) and diarylethene derivatives. The monomer BrNp gave single fluorescence emission at 490 nm, while an apparent room‐temperature phosphorescence (RTP) at 550 nm emerged for P‐BrNp copolymers with various feed ratios. Through fluorescence‐phosphorescence dual emission, P‐BrNp‐0.1 displayed an ultrahigh white‐light emission quantum yield of 83.9 %. Moreover, the subsequent assembly with SBE‐β‐CD further enhanced the phosphorescent quantum yield of P‐BrNp‐0.1 from 64.1 % to 71.3 %, accompanied by the conversion of photoluminescence emission from white to yellow. Diarylethene monomers were introduced as photoswitches to realize reversible RTP emission, which can be used in switchable data encryption and multifunctional writing ink.