All‐Visible Light‐Activated Photoswitching of Diarylethenes via Direct Triplet Sensitization From Low‐Toxicity ZnSe/ZnS Quantum Dots

ABSTRACT

Developing all‐visible light‐activated diarylethene (DAE) molecular photoswitches hold great promise for high‐resolution bioimaging and smart photoresponsive materials. Herein, we demonstrate that a bicomponent system comprising low‐toxicity ZnSe/ZnS quantum dots (QDs) and carboxylated DAEs achieves all‐visible light‐activated photoswitching through a single‐step triplet energy transfer (TET) in both organic and aqueous media. The photoswitching process exhibits reversible photoisomerization and fatigue resistance over multiple cycles under alternating 405 and 590 nm irradiation. The photocyclization quantum yield (${\varnothing }_{o\to c}$ = 55%) of DAEs in our design represents a record‐high efficiency of DAEs under visible light activation compared with previously reported QD‐sensitized and organic‐sensitized systems. The high yield stems from the enhanced quality and a large molar extinction coefficient of ZnSe/ZnS QDs and efficient TET from ZnSe/ZnS QDs to dynamically enchored DAEs. Importantly, a biocompatible photoswitching system was constructed through the self‐assembly of amphiphilic 1,2‐Distearoyl‐sn‐glycero‐3‐phosphoethanolamine‐polyethylene glycol with the mixture of DAEs and ZnSe/ZnS QDs, enabling efficient and reversible photoisomerization of DAEs under all‐visible light irradiation in aqueous media. Our strategy not only paves the way for advancing the development of all‐visible light‐activated optoelectronic devices but also creates new opportunities in further biological applications.

An efficient, all‐visible light‐activated photoswitching of diarylethenes is achieved via single‐step triplet energy transfer from low‐toxicity ZnSe/ZnS quantum dots, enabling reversible photoisomerization in both organic and aqueous media with high photoconversion yield and photocyclization quantum yield comparable to direct UV light excitation.

1. Introduction

Photoswitchable molecules can undergo reversible isomerization upon light irradiation, accompanied by significant changes in physical and chemical properties, including optical absorption and luminescence, electronic structure and conductivity, polarity and reactivities, etc [1]. These features endow them with great potential for applications in super‐resolution biological imaging [2, 3], smart materials and devices [4, 5], and information and energy storage [6, 7]. Diarylethene (DAE), as one of the most popular photoswitches, has garnered significant attention due to its rapid light response, robust fatigue resistance, and excellent thermal stability [8, 9, 10, 11, 12]. DAE undergoes a reversible photocyclization/cycloreversion interconversion between its 1,3,5‐hexatriene and cyclohexadiene forms, generating the ring‐closed (c‐DAE) and ring‐open (o‐DAE) isomers upon irradiation with light at a specific wavelength [13, 14, 15]. However, many classical DAE photoswitches require high‐energy ultraviolet (UV) light irradiation to trigger the photocyclization reaction, which could cause material degradation, including photobleaching [16], by‐product formation [17], and reduced fatigue resistance [18]. Moreover, the poor tissue penetration depth, phototoxicity, and photodamage of UV light severely limit the application of DAE photoswitches in biological systems [19, 20]. Therefore, the design and development of all‐visible light‐activated DAE photoswitches is crucial for overcoming these limitations.

To date, several strategies have been devised to shift the activation wavelength of DAE photoswitches into the visible region, such as π‐conjugation extension [21], intramolecular proton transfer [22], multiphoton absorption [23], upconversion [24], supramolecular assembly [25], and triplet energy transfer (TET) using metal complexes or thermally activated delayed fluorescence (TADF) molecules [26, 27]. Among these, the TET approach has attracted considerable attention, but the typical use of molecular sensitizers imposes limitations due to the relatively weak light absorption and fixed triplet energy levels [28, 29, 30, 31]. Notably, colloidal semiconductor quantum dots (QDs) have emerged as a particularly promising class of triplet sensitizers due to their size‐tunable bandgap and strong spin–orbit coupling, which mixes singlet and triplet characteristics with a narrow singlet‐triplet energy gap (∆E_ST) [32, 33, 34, 35]. QDs can promote the highly efficient transfer of triplet excitons to surface‐anchored molecules via TET [36, 37, 38, 39]. Our group and others have successfully achieved all‐visible light‐activated DAEs through two sequential TET steps that comprise three components, including QDs, molecular mediators, and photoswitches [40, 41, 42]. Specifically, visible light irradiation photoexcites the QDs, from which the excitation energy is transferred to the molecular mediator via the first TET step, followed by the second TET step, relaying the triplet energy from the mediator to o‐DAE, thereby sensitizing the photocyclization reaction through the triplet‐state pathway. However, the induction of molecular mediators not only complicates the design of the triplet sensitization process but also limits the driving force of TET in the photocyclization reaction, and the overall efficiency strongly depends on two sequential TET steps. An alternative strategy to eliminate the mediator is the direct anchoring of the photoswitches onto the QDs surface, such as carboxylated DAEs dynamically attached to CdS QDs to achieve all‐visible light photoswitching [43]. Although visible light‐activated photoswitches through QD sensitization are appealing, the development of low‐ or non‐toxicity QD sensitized photoswitches that exhibit efficient and stable reversibility under visible light irradiation, especially in aqueous media, remains a major challenge for further biological application [44, 45, 46].

Herein, we report an approach to achieve efficient, all‐visible light‐activated DAE photoswitching sensitized by ZnSe/ZnS QDs through a single‐step TET process that operates in both organic and aqueous media (Scheme 1). In our bicomponent design, carboxylated DAEs can dynamically anchor onto the ZnSe/ZnS QDs surface via coordination bonds, which allows the close proximity for efficient Dexter‐type TET. Upon irradiation with 405 nm light, excited ZnSe/ZnS QDs efficiently transfer both bright and dark excitonic energy to o‐DAE isomer through TET, triggering the photocyclization reaction via the excited triplet energy surface. On the other hand, the photocycloreversion of DAEs under 590 nm light is unaffected by the presence of ZnSe/ZnS QDs. Remarkably, one ZnSe/ZnS QD enables to sensitize at least 20 DAE molecules under visible light activation, and the photoisomerization conversion is as high as that obtained under direct UV irradiation. The photocyclization quantum yield (${\varnothing }_{o\to c}$) of DAEs sensitized by ZnSe/ZnS QDs is determined to be 55%, which surpasses previously reported visible light‐activated approaches, including triplet sensitization based on QDs and organic molecules, upconversion, as well as supramolecular assembly (see Table S2). Our design also exhibits reversibility over ten switch cycles upon alternative visible light irradiation at 405 and 590 nm. Importantly, stable and biocompatible aqueous all‐visible light‐activated photoswitches were also achieved by co‐assembling the ZnSe/ZnS QDs and DAEs with the amphiphilic polymer of 1,2‐Distearoyl‐sn‐glycero‐3‐phosphoethanolamine‐polyethylene glycol (DSPE‐PEG₅₀₀₀) through the hydration method for phase transfer from organic into aqueous phase. This strategy not only provides an all‐visible light‐activated photoswitchable system in aqueous solution with deeper light penetration but also further reduces the toxicity of QDs through a shielding effect, holding great potential for further biological applications.

SCHEME 1.

(a) Schematic illustration of all‐visible light‐activated photoisomerization of carboxylated DAE sensitized by ZnSe/ZnS QDs under alternative 405 and 590 nm light irradiation. (b) Mechanistic pathways of DAE photoisomerization through the TET process. Blue lines: visible light‐activated photocyclization (o‐DAE to c‐DAE) via TET from excited ZnSe/ZnS QDs. Orange lines: visible light‐induced photocycloreversion (c‐DAE to o‐DAE) via the singlet excited state (S₁) of c‐DAE. Purple lines: general UV light‐induced photocyclization via the S₁ of o‐DAE.

2. Results and Discussion

2.1. Materials and Characterization

ZnSe QDs with a diameter of ∼4.0 nm (Figure S1) were synthesized based on literature hot‐injection procedures [47, 48]. To passivate surface traps without compromising energy transfer efficiency from QDs, a thin layer of ZnS with a thickness of 1.0 nm was coated on the ZnSe core. Transmission electron microscopy (TEM) analysis reveals that the synthesized ZnSe/ZnS core/shell QDs exhibit a highly monodisperse and uniform morphology with an average diameter of ∼6.0 nm (Figure 1a). To investigate the crystal structure of the synthesized QDs, x‐ray diffraction (XRD) measurement was performed (Figure 1b). The patterns exhibit three distinct peaks corresponding to (111), (220), and (311) planes, consistent with the zinc‐blende structure of both ZnSe and ZnS. Slight shifts of these peaks to higher angles are observed in ZnSe/ZnS QDs, which are attributed to lattice strain from the epitaxial growth of the ZnS shell. These structural features collectively confirm the high crystalline quality of the synthesized ZnSe/ZnS QDs. The photoluminescence quantum yield (PLQY) of ZnSe/ZnS QDs was determined to be 78% by using a reference method. The absorption and PL spectra of ZnSe/ZnS QDs in toluene are shown in Figure 1c, with the first exciton absorption peak at 406 nm and the emission peak centered at 417 nm.

FIGURE 1.

Optical properties of ZnSe/ZnS QDs and DAE. (a) TEM image and corresponding size distribution histogram (inset) of ZnSe/ZnS QDs. (b) XRD pattern of ZnSe core and ZnSe/ZnS QDs. (c) Absorption and PL spectra of ZnSe/ZnS QDs (0.5 µM) in toluene. (d) Absorption spectra of o‐DAE (10 µM) in toluene and after irradiation with 310 nm (250 s) and 590 nm (150 s) light. The inset chemical structures illustrate the reversible photoisomerization between o‐DAE and c‐DAE upon 310 and 590 nm light irradiation.

The DAE with carboxylated function group was synthesized following previous reports [11, 49] and characterized (see the Supporting Information for more details, Scheme S1 and Figures S2–S4). Figure 1d shows the absorption spectra and corresponding molecular configurations of o‐DAE and c‐DAE isomers, which can be reversibly interconverted under UV and visible light irradiation. Upon irradiation with 310 nm light (5.40 mW cm⁻² for 250 s), o‐DAE converts to c‐DAE, resulting in the appearance of two new absorption bands centered at 385 and 600 nm. The photostationary state (PSS) of DAE upon exposure to 310 nm light consists of 80% c‐DAE and 20% o‐DAE [11]. Subsequently, after irradiation with 590 nm light (74.91 mW cm⁻² for 150 s), the absorption spectrum fully recovers to the initial state. These results confirm that the reversible interconversion between o‐DAE and c‐DAE isomers upon alternating irradiation with UV and orange light.

2.2. All‐Visible Light‐Activated Photoisomerization

To demonstrate the all‐visible light‐activated photoisomerization of DAEs, a mixed solution of ZnSe/ZnS QDs (0.5 µM) and DAEs (10 µM) was prepared in deaerated toluene, and the absorption spectra are shown in Figure 2a. The absorption spectrum of o‐DAE remained unchanged after mixing the ZnSe/ZnS QDs, indicating no interaction between DAE and ZnSe/ZnS QDs at the ground state. Upon irradiation with 405 nm light (3.57 mW cm⁻² for 25 s), the appearance of the absorption band centered at 600 nm confirms the photoisomerization from o‐DAE to c‐DAE, reaching a PSS comprising 80% c‐DAE. This PSS composition is identical to that obtained by direct 310 nm light excitation of DAE alone (for 250 s), demonstrating that visible light‐activated photocyclization of DAE can be efficiently achieved in the presence of the ZnSe/ZnS QDs. The high conversion yield (80%) significantly exceeds those (<25%) previously reported for the mediator‐dependent three‐component system [41]. Additionally, one ZnSe/ZnS QD can efficiently sensitize the photocyclization of at least 20 DAE molecules. This capability is comparable to that of the reported all‐visible light photoswitching system based on toxic CdS QDs [43]. Since o‐DAE exhibits no detectable absorption at 405 nm, direct photoisomerization of DAE by this light through the singlet excited state can be ruled out, and no changes in the absorption spectrum of o‐DAE are observed under 405 nm irradiation (Figure S5). Consequently, the observed visible light‐activated conversion from o‐DAE to c‐DAE could be attributed to the sensitization by ZnSe/ZnS QDs through the triplet excited state (vide infra). Subsequently, further irradiation of the mixed solution with 590 nm light for 150 s, the absorption band (450–750 nm) disappears, and the spectrum recovers to the initial state of o‐DAE mixed with ZnSe/ZnS QDs. It confirms that the dual‐visible light photoswitching of DAEs can be successfully achieved upon introducing ZnSe/ZnS QDs.

FIGURE 2.

Absorption spectra of all‐visible light‐activated photoisomerization of a mixture containing ZnSe/ZnS QDs (0.5 µM) and DAE (10 µM). (a) Absorption spectra of the mixed solution after 405 nm (25 s) and 590 nm (150 s) light irradiation. (b) Reversible o‐DAE and c‐DAE photoisomerization of the mixed solution was monitored by the absorbance at 600 nm during ten alternating cycles of 405 nm (25 s) and 590 nm (150 s) light irradiation.

To comprehensively evaluate the efficiency of our all‐visible light‐activated photoswitching system, the photoisomerization QYs of DAE mixed with ZnSe/ZnS QDs were determined according to previous reports [50, 51, 52]. The triplet sensitized ${\varnothing }_{o\to c}$ of DAE in the presence of ZnSe/ZnS QDs under 405 nm irradiation is about 55%, which is approaching that for direct 310 nm excitation of DAE alone (59%, Table S1). Notably, this ${\varnothing }_{o\to c}$ stands as the highest reported to date for visible light‐activated DAE via triplet sensitization based on QDs and organic molecules, upconversion, as well as supramolecular assembly (Table S2). The superior performance originates from the enhanced quality of the ZnSe/ZnS nanocrystal, coupled with their significantly larger molar extinction coefficient (2.9 × 10⁶ L mol⁻¹ cm⁻¹ at 405 nm), which collectively boosts both the light harvesting capacity and the energy transfer efficiency by minimizing non‐radiative losses. The photocycloreversion QYs of DAE under 590 nm light are almost identical in the presence (0.84%) and absence (0.86%) of ZnSe/ZnS QDs, confirming that ZnSe/ZnS QDs have no impact on the back conversion from c‐DAE to o‐DAE. To further investigate the reversibility and fatigue resistance of the mixed solution of ZnSe/ZnS QDs and DAE under all‐visible light control, the absorption spectral changes at 600 nm were monitored over ten alternating irradiation cycles with 405 and 590 nm light (Figure 2b). The photoswitching proceeds with slight fatigue, and the photoisomerization efficiency decreased by approximately 19% after ten cycles, which is attributed to the photodegradation of the ZnSe/ZnS QDs under prolonged light exposure (Figure S6).

2.3. Mechanistic Investigation of Triplet Sensitization

To gain further insight into the mechanism of our all‐visible light‐activated system, steady‐state and time‐resolved PL measurements of ZnSe/ZnS QDs were performed in the absence and presence of o‐DAE. ZnSe/ZnS QDs exhibit an emission band with the PL maximum at 417 nm, and the PL intensity is significantly quenched upon introduction of o‐DAE (Figure 3a). The PL decay yields an amplitude‐weighted average lifetime of 9.6 ns for ZnSe/ZnS QDs (Table S3), which is also markedly reduced with the addition of o‐DAE (Figure 3b). When the molar ratio of ZnSe/ZnS QDs to o‐DAE reaches 1:20, the PL lifetime shortens to 7.2 ns, corresponding to an energy transfer efficiency of 25%. Notably, this 25% energy transfer is sufficient to drive the efficient photocyclization of 20 o‐DAE molecules, highlighting the efficient energy transfer process. Although a previously reported DAE‐CdS QD system achieved a higher energy transfer efficiency (93%) at a similar molar ratio [43], our system requires substantially less absolute energy transfer to accomplish the same photoconversion. This benefits from the ∼3.9‐fold higher PLQY of the ZnSe/ZnS QDs (78%) compared to the CdS QDs (20%), which provides more excitons available for the energy transfer and reduces the non‐radiative pathway. Furthermore, Stern‐Volmer analysis based on both the PL intensity and lifetime was performed to evaluate the quenching efficiency (Figure 3c). The linear fitting of Stern‐Volmer plots yielded the bimolecular quenching constants (k_q ) of 4.44 × 10¹² L mol⁻¹ s⁻¹ for PL intensity and 3.54 × 10¹² L mol⁻¹ s⁻¹ for PL lifetime, respectively. The quenching constants are one order of magnitude higher than the expected diffusion‐controlled rate constant in toluene. It can be attributed to the capability of DAE molecules to dynamically anchor on the ZnSe/ZnS QDs surface, ensuring close proximity and thereby enabling highly efficient energy transfer.

FIGURE 3.

Mechanistic investigation of triplet sensitization through PL quenching and fsTA spectra of ZnSe/ZnS QDs. (a) PL spectra and (b) time‐resolved PL decay at 417 nm of ZnSe/ZnS QDs (0.5 µM) without and with o‐DAE (5, 10, 17.5, 25 µM) in toluene. (c) Stern‐Volmer plots and linear fits for PL intensity and lifetime quenching of ZnSe/ZnS QDs by adding o‐DAE. fsTA spectra of (d) ZnSe/ZnS QDs and (e) the mixed solution of o‐DAE and ZnSe/ZnS QDs. (f) The TA kinetics of ZnSe/ZnS QDs probed at 406 nm with (blue) and without (purple) surface‐bound o‐DAE.

To further investigate the energy transfer process from ZnSe/ZnS QDs to DAEs, femtosecond transient absorption (fsTA) spectroscopy was employed. The fsTA spectra of ZnSe/ZnS QDs alone under 390 nm pulsed pump exhibit a characteristic exciton bleach at ∼410 nm (Figure 3d) with a lifetime of 3.96 ns (Figure 3f, purple triangles), consistent with previous reports [53]. For the triplet sensitized study, a large excess of o‐DAE molecules (QDs:o‐DAE molar ratio of 1:500) was employed to ensure a pronounced signal. Under these conditions, the fsTA spectral feature of ZnSe/ZnS QDs remains unchanged (Figure 3e), while the recovery of the exciton bleach is significantly accelerated, exhibiting a shortened lifetime of 0.13 ns (Figure 3f, blue triangles). This corresponds to a near‐quantitative energy transfer efficiency of ∼97%. A weak negative absorption feature appears around 600 nm, arising from the partial photocyclization of o‐DAE to c‐DAE induced by prolonged exposure to the 390 nm pump excitation. No other transient signals are observed up to 7 ns, indicating that no significant charge transfer occurs from ZnSe/ZnS QDs to o‐DAE. Furthermore, Förster resonance energy transfer can also be excluded in this system, as there is no spectral overlap between the PL of ZnSe/ZnS QDs and the absorption of o‐DAE or c‐DAE isomer. Additionally, according to density functional theory (DFT) calculation, the T₁ energy of o‐DAE is estimated to be 2.84 eV (see computational details in the Supporting Information and Table S4), which is lower than the excited state of ZnSe/ZnS QDs (∼3.06 eV, estimated from the peak of the first excitonic transition) with the mixed singlet and triplet character. This energy alignment allows the thermodynamically favorable pathway for TET occurred from ZnSe/ZnS QDs to o‐DAE. Therefore, we conclude that TET is the main mechanism responsible for ZnSe/ZnS QD‐sensitized o‐DAE photoisomerization.

2.4. Photoisomerization in Aqueous Media

To achieve DAE photoisomerization in aqueous media, a stable and biocompatible photoswitching system (QDs‐DAE@NPs) was developed through a thin‐film hydration and self‐assembly strategy (Figure 4a). Specifically, the mixture of ZnSe/ZnS QDs and DAEs was co‐transferred from toluene into deionized water along with the amphiphilic block copolymer DSPE‐PEG₅₀₀₀. The ultrasmall size of ZnSe/ZnS QDs and the long hydrophobic chains of their surface ligands facilitate efficient encapsulation together with DAEs within the hydrophobic core formed by the DSPE segments. Concurrently, the hydrophilic PEG segments extend into the aqueous phase, rendering the resulting QDs‐DAE@NPs water‐soluble and biocompatible. This DSPE‐PEG₅₀₀₀‐mediated encapsulation not only ensures colloidal stability but also preserves the photophysical properties of ZnSe/ZnS QDs and DAEs. The morphology and size distribution of ZnSe/ZnS QDs in the micelle after aqueous phase transfer were further analyzed by TEM (Figure 4b). The TEM images reveal that ZnSe/ZnS QDs remain highly monodisperse, with an average diameter of 6.3 nm. This result is comparable to that of the ZnSe/ZnS QDs before aqueous transfer, indicating that the DSPE‐PEG₅₀₀₀ encapsulation process induces a negligible impact on ZnSe/ZnS QDs.

FIGURE 4.

All‐visible light‐activated photoisomerization of DAE mixed with ZnSe/ZnS QDs in aqueous media. (a) Schematic illustration of the preparation process of an aqueous photoswitchable system of ZnSe/ZnS QDs and DAE by the thin‐film hydration method. (b) TEM image and corresponding size distribution histogram (inset) of aqueous ZnSe/ZnS QDs. (c) Absorption spectral changes of aqueous photoswitch containing ZnSe/ZnS QDs (0.5 µM) and DAE (5 µM) upon 405 nm (6 s) and 590 nm (90 s) light irradiation.

To clearly understand the state of QDs‐DAE@NPs in aqueous media, we carried out dynamic light scattering (DLS) measurements (Figure S7). It reveals a hydrodynamic diameter of approximately 29.39 nm with a polydispersity index (PdI) of 0.207, indicating a monodisperse and uniform nanoparticle population. Notably, combining the known hydration layer thickness of DSPE‐PEG₅₀₀₀ (∼11 nm per side) [54], the measured hydrodynamic diameter (29.39 nm) indicates that each DSPE‐PEG₅₀₀₀ micelle consists of a single ZnSe/ZnS QD. Furthermore, the larger‐scale TEM image also clearly reveals a micelle layer surrounding each ZnSe/ZnS QD (Figure S8). The zeta potential was determined to be −21.3 mV (Figure S9), which suggests good colloidal stability due to sufficient electrostatic repulsion. Additionally, to evaluate the storage stability of QDs‐DAE@NPs in aqueous media, we monitored the DLS size distribution over seven days of storage in water (Figure S10). The results showed negligible changes in particle size over the seven days, confirming that the QDs‐DAE@NPs remain well‐dispersed without aggregation or degradation.

We assessed that the triplet sensitized all‐visible light‐activated photoisomerization of QDs‐DAE@NPs also occurred in aqueous media. Under 405 nm light irradiation (3.57 mW cm⁻² for 6 s), the aqueous dispersion of QDs‐DAE@NPs exhibited the appearance of a new absorption band around 600 nm, with an efficiency and PSS identical to those observed in toluene (Figure 4c and Figure S11). This efficient TET benefits from the pre‐established proximity between the ZnSe/ZnS QDs and DAE in toluene, which is preserved upon their co‐encapsulation into DSPE‐PEG₅₀₀₀ assemblies. The intrinsic proximity‐driven design contrasts sharply with previously reported systems using organic TADF sensitizers, where high TET rates were achieved only under the nanoconfinement effect imposed by micelles [27]. Upon illumination with 590 nm light (74.91 mW cm⁻² for 90 s), the absorption spectrum of the original o‐DAE was completely regenerated, demonstrating a full reversible photocyclization/cycloreversion in aqueous media. To further examine the biocompatibility of our system, the cytotoxicity of QDs‐DAE@NPs was assessed at various concentrations using the CCK‐8 assay (Figure S12). The results showed that the cell viability of QDs‐DAE@NPs‐treated HeLa cells remained around 91.4% at a concentration up to 0.9 µM, which indicates that QDs‐DAE@NPs have low cytotoxicity and good biocompatibility. It should be noted that the encapsulation of ZnSe/ZnS QDs and DAE within DSPE‐PEG₅₀₀₀ micelles can further eliminate the toxicity of the QDs and aromatic hydrocarbon materials, thereby significantly enhancing the biocompatibility of the system. Collectively, these results establish the QDs‐DAE@NPs system as an efficient, low‐toxicity, and fully aqueous approach for all‐visible light‐activated photoswitching, paving a promising avenue for implementing dynamic optical control in biological environments.

3. Conclusions

In conclusion, we have developed an all‐visible light‐activated DAE photoswitch based on low‐toxicity ZnSe/ZnS QDs as triplet sensitizers in both organic and aqueous media. ZnSe/ZnS QDs serve as efficient triplet sensitizers for DAE photocyclization owing to their excellent photophysical properties, including large molar absorptivity, high PLQY, size‐tunable energy levels, strong spin–orbit coupling, together with their low‐toxicity nature. Under 405 nm light irradiation, the photoisomerization from o‐DAE to c‐DAE is achieved via TET from ZnSe/ZnS QDs. This photoswitching process displays efficient photoisomerization and fatigue resistance over multiple irradiation cycles. PL quenching and transient absorption spectroscopy analysis confirm that the efficient TET mechanism from ZnSe/ZnS QDs to o‐DAEs, with quenching constants beyond the diffusion‐controlled rate. Importantly, we have developed a stable, aqueous‐phase photoswitching system via DSPE‐PEG₅₀₀₀ encapsulation of ZnSe/ZnS QDs and DAE using thin‐film hydration and self‐assembly strategy. Our future efforts will focus on translating the biocompatible QDs‐DAE@NPs system into bioimaging applications, to pave the way for all‐visible light‐activated, aqueous photoswitching strategy to broad applications in the biological field.

Conflicts of Interest

The authors declare no conflicts of interest.

Supporting information

Supporting File: smll73996‐sup‐0001‐SuppMat.docx.

Data Availability Statement

The data that support the findings of this study are available from the corresponding author upon reasonable request.