Oxygen and relative humidity monitoring with films tailored for enhanced photoluminescence

Approaches to generate porous or doped sensing films, which significantly enhance the photoluminescence (PL) of oxygen optical sensors, and thus improve the signal-to-noise (S/N) ratio, are presented. Tailored films, which enable monitoring the relative humidity (RH) as well, are also presented. Effective porous structures, in which the O₂-sensitive dye Pt octaethylporphyrin (PtOEP) or the Pd analog PdOEP was embedded, were realized by first generating blend films of polyethylene glycol (PEG) with polystyrene (PS) or with ethyl cellulose (EC), and then immersing the dried films in water to remove the water-soluble PEG. This approach creates pores (voids) in the sensing films. The dielectric contrast between the films’ constituents and the voids increases photon scattering, which in turn increases the optical path of the excitation light within the film, and hence light absorption by the dye, and its PL. Optimized sensing films with a PEG:PS ratio of 1:4 (PEG’s molecular weight M_w ∼8000) led to ∼4.4× enhancement in the PL (in comparison to PS films). Lower M_w ∼200 PEG with a PEG:EC ratio of 1:1 led to a PL enhancement of ∼4.7×. Film-dependent PL enhancements were observed at all oxygen concentrations. The strong PL enhancement enables (i) using lower dye (luminophore) concentrations, (ii) reducing power consumption and enhancing the sensor’s operational lifetime when using organic light emitting diodes (OLEDs) as excitation sources, (iii) improving performance when using compact photodetectors with no internal gain, and (iv) reliably extending the dynamic range.     

Stable deep blue organic light emitting diodes with CIE of y < 0.10 based on quinazoline and carbazole units

Achieving stable deep blue organic light emitting diodes (OLEDs) with narrow full width at half maximum (FWHM) and color gamut in the range of the commission International de L’Eclairage (CIE) of y ≤ 0.10 is still challenging in display and lighting applications. In this investigation, three donor-acceptor (D-A) deep-blue emitters were designed and synthesized via integrating asymmetric quinazoline (PQ) acceptor with weak donating carbazole (Cz) donor. The effect of the position and number of Cz group in PQ unit are investigated, which is also first examples for systematic research about the effect of different position of asymmetric PQ as acceptor on deep OLEDs. Their bandgaps of 3.12∼3.19 eV and the singlet state energy levels of 3.12∼3.19 eV were found to be sufficiently large to achieve deep blue light. As expected, these emitters-based OLEDs exhibit deep blue emission with the maximum wavelength ≤ 450 nm and narrow FWHM ≈ 60 nm. Especially, a CIE of y = 0.080 was achieved for 4PQ-Cz-based OLED. Significantly, the deep blue electroluminescence (EL) spectra of these three emitters-based OLEDs are very stable and the corresponding CIE coordinates deviation (ΔCIE (x, y)) can be negligible under the applied voltage ranging from 5 V to 9 V.     

On the Complementary Photoluminescent and Electroluminescent Images of Poly(phenylenevinylene)‐Based Light‐Emitting Diodes with a Thin Active Layer

A clear complementary relationship between photoluminescent (PL) and electroluminescent (EL) images was observed for organic light‐emitting diodes (OLEDs) based on poly(phenylenevinylene) (PPV) and dye‐doped PPV. So‐called ‘black spots' (dark circular regions observed on the active area of running OLEDs) become bright ones, when the photoluminescence of the same area is excited. A very small thickness of the active layer (ca. 10 nm) was the crucial point to observe this anticorrelation between EL and PL. A substantial increase of the PL yield (‘anti‐burning' effect) was observed after strong light exposure (ca. 10 mJ/cm²) of the polymer covered by an aluminium layer. The same light exposure without aluminium protection resulted in complete photobleaching of the polymer. The presence of a thin insulating layer between the polymer and aluminium was proposed to be responsible for these effects. This layer prevents electron injection and PL quenching due to exciton dissociation at the metal‐polymer interface. The former effect leads to black spots in the EL image, the latter one gives rise to bright spots on the PL image situated on the same places. The intermediate layer can be also induced by light exposure. A very efficient energy transfer from the polymer to the dye and to the J‐aggregates of the dye was demonstrated in PPV/dye composite films.     

Molecular Orientation Effects in Organic Light‐Emitting Diodes

It is well known that by horizontally aligning the transition dipole moments of exciton dipoles in the emitter films of organic light‐emitting diodes (OLEDs), a larger fraction of the radiative power can escape from the OLED stack, increasing the light outcoupling efficiency by up to 50 % compared to the isotropic counterparts. In this account, we review recent advances in understanding this phenomenon, with a special focus on the practical strategies to control the molecular orientation in vacuum‐deposited films of thermally activated delayed fluorescent (TADF) dyes. The role of molecular orientation in efficient OLED design is discussed, which has been experimentally proven to increase the external quantum efficiency exceeding 30 %. We outline the future challenges and perspectives in this field, including the potential to extend the concept to the solution‐processed films. Finally, the development of multiscale computer simulations is reviewed to assess their potential as a complementary approach to systematically screening OLED molecules in silico.     

Synthesis,characterization, and properties of novel bis(aryl)carbazole-containing N-coumarin derivatives

A series of novel N-coumarin derivatives containing oligothiophene-substituted N-coumarins as the core and bis(aryl)carbazoles as the substituent were synthesized and characterized. Their optical, electrochemical, and thermal properties were investigated. The electroluminescence (EL) properties of the selected materials were also studied. Solution-processed OLEDs with green and yellow light emission, turn-on voltages of 2.7–2.9 V, and maximum luminance efficiencies of up to 3.94 cd A⁻¹ at 17.6 mA cm⁻² (maximum power efficiency of 1.62 lm W⁻¹) were prepared.     

Synthesis and optical properties of fluorene and p-phenylenevinylene copolymers containing non-conjugated spacer

A series of alternating fluorene and p-phenylenevinylene copolymers containing non-conjugated spacer have been synthesized through the Wittig polycondensation reaction. These amorphous copolymers are highly soluble in common organic solvents and can be spin-cast to obtain transparent films. The effects of non-conjugated spacers in the main chain and the methoxyl groups on the side chain on the thermal behavior, photoluminescence (PL) and electroluminescence (EL) properties of these copolymers have been investigated in detail. Single-layered light-emitting diodes (LEDs) have been fabricated in the configuration of ITO/PEDOT/copolymer/Ca/Al and emitted blue light in the range of 456-492 nm. The measurements of current vs voltage show turn-on voltages at 6.2-12.4 V. Among the LEDs based on the six copolymers, the maximum EL brightness and efficiency of the LED based on P1 containing 4CH₂ aliphatic segment length in the main chain and without methoxyl groups on side chain are reached 3936 cd/m² and 0.70 cd/A, respectively.     

Fluorescence of 5-fluorouracil upon the transition from the second singlet excited state <Emphasis Type="Italic">S</Emphasis><Subscript>2</Subscript> to the ground state

Effect of the wavelength of excitation light (λ_ex) on the fluorescence excitation and emission spectra of 5-fluorouracil in acidic solution (pH 2.5) was studied upon excitation at the S ₂ ← S ₀-transition absorption band. It has been found that direct excitation at the second or the shorter wavelength absorption band results in 5-fluorouracil fluorescence that originates not only from the first excited state S ₁ but is also due the transition from the second excited state S ₂ to the ground state.     

An improved method for ratiometric fluorescence detection of pH and Cd using fluorescein isothiocyanate–quantum dots conjugates

In this study, thioglycolic acid capped-CdTe quantum dots (QDs) were modified by polyethylenimine (PEI), and then combined with fluorescein isothiocyanate (FITC) to fabricate FITC–CdTe conjugates. The self-assembly of FITC, CdTe and PEI was ascribed to electrostatic interactions in aqueous solution. The resulting conjugates were developed toward two routes. In route one, ratiometric photoluminescence (PL) intensity of conjugates (I_FITC/I_QDs) was almost linear toward pH from 5.3 to 8.7, and a ratiometric PL sensor of pH was favorable obtained. In route two, firstly added S²⁻ induced remarkable quenching of QDs PL peak (at the “OFF” state), which was restored due to following addition of Cd²⁺ (at the “ON” state). In the conjugates, successive introduction of S²⁻ and Cd²⁺ hardly influenced on FITC PL peaks. According to this PL “OFF-ON” mode, a ratiometric PL method for the detection of Cd²⁺ was achieved. Experimental results confirmed that the I_FITC/I_QDs exhibited near linear proportion toward Cd²⁺ concentration in the range from 0.1 to 15 μM, and the limit of detection was 12 nM. Interferential experiments adequately testified that the proposed sensors of pH and Cd²⁺ were practicable in real samples and complex systems. In comparison with conventional analytical techniques, the ratiometric PL method was simple, rapid, economic and highly selective.     

Comparative study of photoelectric properties of a copolymer and the corresponding homopolymers based on poly(3-alkylthiophene)s

As semiconducting materials in organic light-emitting devices (OLEDs), a novel, highly soluble poly[(3-octylthiophene)-co-(3-(2-ethyl-1-hexylthiophene))] (P3OTIOT) and the corresponding homopolymers (poly(3-octylthiophene) (P3OT) and poly(3-isooctylthiophene) (P3IOT)) were prepared by an FeCl₃-oxidative approach to compare their photoelectric properties. Characterization of the polymers included FT-IR, ¹H NMR, gel permeation chromatography (GPC), thermo-gravimetric analysis (TGA), UV-vis spectroscopy, photoluminescence (PL) and electroluminescence (EL). P3OTIOT and P3OT depicted excellent solubility in common organic solvents. TGA studies showed that all of the materials exhibited very good thermal stabilities, losing 5% of their weight on heating to 300 °C. The optical property investigations showed that the band-gap energy of P3OTIOT was similar to that of P3OT (2.43 eV) at 2.45 eV and 6% lower than that of P3IOT (2.6 eV) in CHCl₃ solution. In PL spectra, the emission maxima of P3OTIOT and P3IOT were 50 nm and 130 nm blue-shifted with respect to that of P3OT, respectively. However, the PL intensity of P3OTIOT was seven times higher than that of P3OT. Single layer polymer light-emitting devices (PLEDs) with the ITO/polymer/Ag configurations were fabricated by the spin-coating method with P3OT, P3IOT and P3OTIOT as the EL materials, which exhibited red (650 nm), orange-red (610 nm) and yellow-green (525 nm) EL, respectively. The external EL quantum efficiencies (QE) of P3IOT and P3OTIOT devices are 6.4 × 10⁻³% and 5.1 × 10⁻³% which are about five and four times higher than that of the P3OT device (1.2 × 10⁻³%), respectively. The turn-on voltage of the P3OTIOT device (5 V) is between that of the P3OT (4.5 V) and P3IOT (6 V) devices. These results indicated that the P3OTIOT combined the photoelectric properties of P3OT and P3IOT with excellent solubility, processability, low band-gap energy, high QE and low turn-on voltage in the PLEDs, and they might be excellent polymeric materials for applications in organic light-emitting diodes, light-emitting electrochemical cells and polymer solar cells.     

Chemical Tailoring Assisted non-TADF to TADF Switching in Carbazole-Benzophenone Emitter – An In-silico Investigation

Organic light-emitting diodes (OLEDs) have become one of the most popular lighting technologies since they offer several advantages over conventional devices. In carbazole-benzophenone (CzBP) OLED devices, the polymeric form of the compound is previously reported to be Thermally Activated Delayed Fluorescence (TADF)-active (ΔE_ST ≈0.12 eV), while the monomer ( CzBP ) (ΔE_ST≈0.39 eV) does not. The present study examines the effect of chemical tailoring on the optical and photophysical properties of CzBP using DFT and TDDFT methods. The introduction of a single −NO₂ group or di-substitution (−NO₂, −COOH or −CN) in the selected LUMO region of the reference CzBP monomer significantly reduces ΔE_ST≈0.01 eV, projecting these systems as potential TADF-active emitters. Furthermore, the chemical modification of CzBP -LUMO alters the two-step TADF mechanism (T₁→T₂→S₁) in CzBP (E_S₁>E_T2>E_T₁) to the Direct Singlet Harvesting (T₁→S₁) mechanism (E_T2>E_S₁>E_T₁), which has recently been identified in the fourth-generation OLED materials.     

Recent Advances in Conjugated TADF Polymer Featuring in Backbone‐Donor/Pendant‐Acceptor Structure: Material and Device Perspectives

Along with the persistent research interest in organic light‐emitting diode (OLED) display and lighting technology, a new studying topic is now focused on developing thermally activated delayed fluorescence (TADF) polymer emitters, with the purpose to achieve high‐performance cost‐effective, solution‐processed OLEDs (s‐OLEDs) purely from fluorescent‐type materials. However, research in this topic is in its infancy about the designing rules of polymer structures, photophysical mechanisms and the correlated devices. In this Personal Account, mainly from our personal experience we will shortly introduce the historical developments, status and perspectives about one representative kinds of TADF polymers, i. e. the conjugated TADF polymers featuring in backbone‐donor/pendant‐acceptor (BDPA) structure scaffold, which shows very promising electroluminescent (EL) performance even using simple s‐OLED structure. Special attention is focused on illustrate the molecular designing & synthesis motivation, chemistry & device tactics towards solving the limiting factors about the quantum yields and aggregation‐quenching tendency in solid states. Further challenges and strategies towards optimizing their overall EL performance, e. g. simultaneous achieving extremely high external quantum efficiency, power efficiency and low roll‐off rate, are also discussed.     

Aggregation phenomena of linear and miktoarm star copolymers of styrene and dimethylsiloxane: Influence of the architecture

The micellar behavior of PS-b-PDMS, PS-b-PDMS-b-PS linear block and (PS)₂(PDMS) miktoarm star copolymers of polystyrene (PS) and polydimethylsiloxane (PDMS) is investigated in DMF, a selective solvent for PS. The linear PS-b-PDMS and star (PS)₂(PDMS) copolymers exhibit different macromolecular architectures but similar compositions and total molecular weight, while the linear PS-b-PDMS-b-PS copolymer has the same composition as the diblock and miktoarm star but double their molecular weight. Static, dynamic light scattering and viscometry were used for the structural characterization of the micelles. Aggregation numbers were found to increase in the order PS-b-PDMS-b-PS < (PS)₂(PDMS) < PS-b-PDMS. The corona thickness was dependent on the molecular weight of the soluble PS chains. In the case of (PS)₂(PDMS), although the core area per PS chain, A_C, was significantly lower than that of the linear copolymers, the coronal chains were not significantly stretched. This can be attributed to the stiff nature of the PS chains, which maintains the elongated form of the chains.     

Photophysics and photochemical dynamics of methylanisole molecules in a supersonic jet

The fluorescence excitation, dispersed fluorescence and hole burning spectra, and fluorescence lifetimes of jet-cooled o-, m-, and p-methylanisoles (MA) were measured. The low-frequency ring methyl internal rotational bands observed for their S₀ and S₁ states were assigned. In the case of m-MA, the rotational isomers of cis and trans conformers, which arise from the orientation of the OCH₃ group with respect to the CH₃ group, were assigned by hole-burning spectroscopy. The observed level energies and relative intensities of the methyl internal rotation were reproduced by a calculation using a free rotor basis set. Furthermore, their potentials in the S₀ and the S₁ states were determined. The potential barrier heights for the S₀ states of m- and p-MA were quite low, suggesting that the methyl groups are freely rotating, while changing from S₀ to S₁ states, the potential barrier height increases. The potential barrier heights of o-MA drastically decreased in going from S₀ to S₁ states. The decrease would be due to the hydrogen bonding between O atom and one H atom of the methyl group. The torsional bands of the methoxy group (–OCH₃) were also observed for p- and o-MA. The –OCH₃ modes are found to couple with the level of the e species for the methyl internal rotation.Fluorescence lifetimes (τ_f) of the methyl internal rotational bands in the S₁ states of o-, m-, and p-MA were measured in order to investigate the photochemical dynamics. The values of the nonradiative rate constant (k_nr) were estimated from the τ_f values and Franck–Condon factors. The k_nr values drastically increased with the excitation of methyl internal rotation. Accordingly, the methyl internal rotation should enhance the nonradiative process, presumably intersystem crossing (ISC). The enhancement should be caused by the increase of the state density (ρ) effectively coupled with triplet manifolds. The drastic increase in the ρ value should be caused by level mixing. In addition, the methyl internal rotational motion may enhance the increase of the coupling matrix elements through the vibronic coupling between the excited singlet states. The remarkable rotational quantum species dependence on the ISC rate constant (k_ISC) value clearly appeared in m-MA. The dependence should result from the difference of the ρ value between a₁ and e species, since the e species are doubly degenerate. The species dependence was apparently related to the potential barrier height, suggesting that the large barrier height should have an influence on the ρ value of the triplet states.     

Synthesis and 1.1 μm near-infrared electrophosphorescence properties of a phenoxy-substituents copper phthalocyanine

A novel copper phthalocyanine bearing phenoxy-substituents was prepared and characterized by MS and Elemental analysis. Its UV/Vis absorption and photoluminescence (PL) spectra were investigated. Organic light-emitting devices (OLEDs) were demonstrated by employing this copper phthalocyanine doped into 4, 4′-N,N′-dicarbazole-biphenyl (CBP). Room-temperature electrophosphorescence was observed at about 1.1 μm due to transitions from the first excited triplet state to the singlet ground state (T ₁–S₀) of this CuPc. The intensity of NIR emission at lower doping concentrations (about 10 wt %) was extremely high compared with devices doped with fluorescent dyes. The results indicated that direct charge trapping appears to be the dominant mechanism. The article is published in the original.     

High luminance phosphorescent organic light emitting diodes based on Re(I) complex

A novel Re(I) complex with the acenaphtho[1,2-b]pyrazino[2,3-f][1,10]phenanthroline (APPT) ligand Re(APPT)(CO)₃Br (abbreviated as Re-APPT) was used to fabricate organic light emitting diodes (OLEDs). From the electroluminescence (EL) spectra of the device at different bias voltages, it could be found that the EL maxima shifted approximately 30 nm. For OLEDs with 5% Re-APPT doped emissive layer, turn-on voltage of 6 V, maximum luminance of 7631 cd/m² and a current efficiency up to 2.36 cd/A were obtained. We suppose that a direct charge trapping took the dominant position in the EL process. Trapping contributed mostly to this relatively higher luminance.     

Novel photoluminescent lanthanidomesogens forming bilayer smectic phase derived from blue light emitting liquid crystalline, one ring O-donor Schiff-base ligands

A series of new mononuclear lanthanide(III)-salicylaldimine complexes of the type [Ln(LH)₃(NO₃)₃] (Ln = La, Pr, Sm and Gd; LH = N-(2-hydroxyethyl)-4n-alkoxysalicylaldimine, n = 14, 18) have been synthesized and characterized by FT-IR, ¹H NMR, ¹³C NMR, UV-Vis, FAB-mass and magnetic susceptibility measurements. The ligand (LH) coordinate to lanthanide ions in zwitterionic form via the phenolic-oxygen with the proton shifted to the imine-nitrogen. The nitrato groups occurring in chelated bidentate fashion complete a nine-coordinate geometry. Polarized optical microscopy (POM) and differential scanning calorimetry (DSC) show that the ligands are monotropic and their complexes exhibit enantiotropic highly viscous smectic A (SmA) mesophase in the temperature range 60-185 °C. A bilayer self organized assembly of the molecules in the mesophase are proposed on the basis of the small angle XRD study. The ligands are blue light emitters with a broad emission maxima at ∼447 nm while the lanthanide complexes show intense emission in the visible range (∼465-679 nm) at 350 nm excitation. The samarium(III) complex, [Sm(LH)₃(NO₃)₃] is distinct from the rest in emitting bright orange light (∼660 nm, Φ = 48%). The S_o-S₁ excitation band being stronger than the direct f-f excitation in the samarium complex clearly suggests that the Schiff-base ligands efficiently sensitize the luminescence of Sm³⁺. DFT calculations have been performed using DMol3 program at BLYP/DNP level to obtain the stable electronic structure of the ligand and complex.     

Phenothiazine‐S,S‐dioxide‐ and fluorene‐based light‐emitting polymers: Introduction of e−‐deficient S,S‐dioxide into e−‐rich phenothiazine

A novel series of poly(10‐hexyl‐phenothiazine‐S,S‐dioxide‐3,7‐diyl) and poly(9,9′‐dioctyl‐fluorene‐2,7‐diyl‐alt‐10‐hexyl‐3,7‐phenothiazine‐S,S‐dioxide) (PFPTZ‐SS) compounds were synthesized through Ni(0)‐mediated Yamamoto polymerization and Pd(II)‐catalyzed Suzuki polymerization. The synthesized polymers were characterized by ¹H NMR spectroscopy and elemental analysis and showed higher glass transition temperatures than that of pristine polyfluorene. In terms of photoluminescence (PL), the PFPTZ‐SS compounds were highly fluorescent with bright blue emissions in the solid state. Light‐emitting devices were fabricated with these polymers in an indium tin oxide/poly(3,4‐ethylene dioxythiophene):poly(styrene sulfonate)/polymer/Ca/Al configuration. The electroluminescence (EL) of the copolymers differed from the PL characteristics: the EL device exhibited a redshifted greenish‐blue emission in contrast to the blue emission observed in the PL. Additionally, this unique phenothiazine‐S,S‐dioxide property, triggered by the introduction of an electron‐deficient SO₂ unit into the electron‐rich phenothiazine, gave rise to improvements in the brightness, maximum luminescence intensity, and quantum efficiency of the EL devices fabricated with PFPTZ‐SS. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 1236–1246, 2007     

Multifunctional Materials Serving as Efficient Non-Doped Violet-Blue Emitters and Host Materials for Phosphorescence

Efficient multifunctional materials acting as violet-blue emitters, as well as host materials for phosphorescent OLEDs, are crucial but rare due to demand that they should have high first singlet state (S₁) energy and first triplet state (T₁) energy simultaneously. In this study, two new violet-blue bipolar fluorophores, TPA-PI-SBF and SBF-PI-SBF , were designed and synthesized by introducing the hole transporting moiety triphenylamine (TPA) and spirobifluorene (SBF) unit that has high T₁ into high deep blue emission quantum yield group phenanthroimidazole (PI). As the results, the non-doped OLEDs based on TPA-PI-SBF exhibited excellent EL performance with a maximum external quantum efficiency (EQE_max) of 6.76 % and a violet-blue emission with Commission Internationale de L′Eclairage (CIE) of (0.152, 0.059). The device based on SBF-PI-SBF displayed EQE_max of 6.19 % with CIE of (0.159, 0.049), which nearly matches the CIE coordinates of the violet-blue emitters standard of (0.131, 0.046). These EL performances are comparable to the best reported non-doped deep or violet-blue emissive OLEDs with CIEy<0.06 in recent years. Additionally, the green, yellow and red phosphorescent OLEDs with TPA-PI-SBF and SBF-PI-SBF as host materials achieved a high EQE_max of about 20 % and low efficiency roll-off at the ultra-high luminance of 10 000 cd m⁻². These results provided a new construction strategy for designing high-performance violet-blue emitters, as well as efficient host materials for phosphorescent OLEDs.     

Spectroscopic and Molecular Docking Approaches for Investigation of Interaction of Phellopterin with Human Serum Albumin

The mechanism of interaction between human serum albumin (HSA) and natural product phellopterin (PL) from Angelica dahurica was investigated by spectroscopic techniques with molecular docking under simulated physiological conditions. The experimental results showed that the fluorescence of HSA was regularly quenched by PL, and the quenching constants (K_SV) decreased with increasing temperature, which indicated that the quenching mechanism was a static quenching procedure. The binding constants (K_A) were larger than 10^?5 M^?1 and the number of binding sites (n) was approximate to 1 at different temperatures, which indicated that the binding affinity was hige and there was just one main binding site in HSA for PL. According to thermodynamic parameters from Van't Hoff equation, the binding process of PL with HSA was spontaneous and exothermic process due to ΔG < 0, and the electrostatic force played major role in the binding between PL and HSA according to ΔH < 0 and ΔS > 0. The binding distance (r) was calculated to be about 3.35 nm, which implied that the energy transfer from HSA to PL occurred with high possibility according to the theory of Förster's non-radiation energy transfer. The microenvironment and conformation of HSA changed with the addition of PL based on the results of synchronous and three-dimensional fluorescence methods. The molecular docking analysis revealed the binding locus of PL to HSA in subdomain IIIA (Sudlow's site II).     

In-situ synthesis of stable perovskite quantum dots in core-shell nanofibers via microfluidic electrospinning

Perovskite quantum dots (PQDs) possess remarkable optical properties, such as tunable photoluminescence (PL) emission spectra, narrow full width at half maximum (FWHM) and high PL quantum yield (QY), endowing the PQDs great application prospects. However, the inherent structural instability of PQDs has seriously hindered the application of PQDs in various photoelectric devices. In this work, a microfluidic electrospinning method was used to fabricate color-tunable fluorescent formamidinium lead halogen (FAPbX₃, X = Cl, Br, I) PQDs/polymer core-shell nanofiber films. The core-shell spinning nanofiber not only supplies the interspace for the in-situ formation of PQDs, but also significantly reduces the permeability of moisture and oxygen in the air, which greatly improves the stability of PQDs. After adjusting the composition of precursors, the blue-emissive polystyrene (core) and polymethyl methacrylate (shell) coated FAPbCl₃ QDs (abbreviated as PS/FAPbCl₃/PMMA, hereinafter), green-emissive PS/FAPbBr₃/PMMA and red-emissive PS/FAPbI₃/PMMA nanofiber films were fabricated with the highest PL QY of 82.3%. Moreover, the PS/FAPbBr₃/PMMA nanofiber film exhibits great PL stability under blue light irradiation, long-term storage in the air and water resistance test. Finally, the green- and red-emissive nanofiber films were directly applied as light conversion films to fabricate wide-color-gamut display with the color gamut of 125%, indicating their tremendous potentials in optoelectronic applications.