Temperature-dependent Photoluminescence Properties Research Articles

A four-mode optical thermometer designed in double perovskite Ca2GdNbO6:Bi3+,Eu3+

High-sensitive multi-mode optical thermometry has become a superstar in the temperature sensing field and attracted great attention. Herein, a novel four-mode optical thermometer is designed in Eu3+ and Bi3+ co-doped double perovskite Ca2GdNbO6. The crystal structures of the host and the doped samples were characterized with X-ray diffraction patterns and Rietveld refinements. Under the excitation of 340 nm, the phosphors exhibit multiple emissions coming from Bi3+ and Eu3+. The energy transfer from Bi3+ to Eu3+ is proved in the perovskite and the transfer efficiency reaches as high as 92%. Benefiting from the different temperature-dependent photoluminescent properties of Bi3+ and Eu3+, a four-mode optical thermometer based on fluorescence intensity ratio, CIE coordinate, fluorescence lifetime, and excitation intensity ratio is realized in the Ca2GdNbO6:0.03Bi3+,0.01Eu3+ phosphor. The maximal relative sensitivities of the four modes are 1.90% K−1 at 460 K, 0.514% K−1 at 500 K, 2.69% K−1 at 437 K, and 1.43% K−1 at 310 K, respectively, most of which are higher than those of recently reported phosphors. These good thermometric performances suggest that Ca2GdNbO6:Bi3+,Eu3+ has a great potential application in temperature detection field.

Temperature dependence of magnetic sensitivity in ensemble NV centers

The magnetic sensitivity of the ensemble NV centers is directly related to temperature. In this study, we systematically investigated the temperature dependence of photoluminescence properties and optical detection magnetic resonance in ensemble NV centers from 1.6 K to 300 K. The magnetic sensitivity of the ensemble NV centers increases with the temperature rising in the range of 1.6 K to 75 K due to changes in contrast and linewidth, reaching a minimum near 40 K. Furthermore, the decrease in sensitivity is attributed to laser intensity overload at low temperatures by studying the influence of laser power on contrast and linewidth. These results offer valuable insights into NV magnetic sensing applications.

Synthesis and erudite insight into the structural, luminescence and thermal sensing characteristics of Sm3+ incorporated [formula omitted]-BaB2O4 novel phosphors

In this paper, we have presented the comprehensive characterization of red-light-emitting novel β-BaB2O4:xSm3+ (x = 0.5, 0.75, 1, 1.5, and 2 mol%) phosphor samples synthesized by making use of solid-state reaction method. The XRD patterns verified the successful synthesis and in-depth analyses were carried out to explore the structural, luminescence, and thermal properties. Notably, the introduction of Sm3+ through doping did not result in any substantial alterations in the crystal structure. Photoluminescence (PL) emission spectra exhibited 4 distinct peaks for 401 nm excitation. Out of these 4 peaks, the prominent peak was present at 601 nm, attributed to the magnetic dipole-allowed transition 4G5/2 → 6H7/2. The colorimetric analysis revealed the correlated color temperature (CCT) to be around 1700 K, accompanied by 99.9 % colour purity. The optimal doping concentration, before luminescence quenching, was identified as 1 mol%, with multipole-multipole interactions identified as the predominant quenching mechanism. Diffuse reflectance spectroscopy (DRS) studies on β-BaB2O4:1%Sm3+ confirmed characteristic peaks corresponding to Sm3+ transitions, revealing an ionic bonding nature between Sm3+ and the host. Also, the direct optical band gap was determined to be 5.62 eV. Furthermore, the optimized phosphor demonstrated exceptional temperature-dependent photoluminescent (TDPL) properties, exhibiting a negligible (∼5 %) decrease in emission intensity for prominent peaks even at 440 K. Overall, the phosphors displayed high activation energy, significant thermal stability, and thermal sensing properties, making them promising candidates for various optoelectronic applications.

Structural and temperature-dependent photoluminescence properties of NaBaBO3:Ce3+,Tb3+ phosphors synthesized using the combustion method

This study explores the structural and temperature-dependent photoluminescence of Ce3+ and Tb3+ doped NaBaBO3 phosphors, synthesized via combustion. Analysis of their crystal structures confirmed excellent alignment with the standard PDF#98–008-0110. Investigation into both room and low-temperature photoluminescence revealed that the dopants have a significant effect on emission spectra. Ce3+-doped samples exhibited excitation peaks at 275 nm and 358 nm, leading to a primary emission at 419 nm, with enhanced low-temperature emission suggesting reduced non-radiative processes. Tb3+-doped phosphors showed excitation from 250 to 377 nm and emissions from blue to deep red, including strong green emission at 550 nm due to 5D4→7F5 transitions. Optimal doping was found at 1 mol% for Ce3+, while Tb3+ showed increased luminescence up to 3 mol%, with concentration quenching observed beyond these points. The study indicates dipole–dipole interactions dominate Ce3+ concentration quenching, whereas Tb3+ involves both electric dipole and quadrupole interactions. This analysis provides insights into enhancing luminescent efficiency and suggests NaBaBO3:xCe3+,Tb3+ phosphors' potential in advancing white LED technology, highlighting their stable luminescent properties at low temperatures.

Molybdate-Templated Luminescent Silver Alkynyl Nanoclusters: Total Structure Determination and Optical Property Analysis.

Two novel MoO42--templated luminescent silver alkynyl nanoclusters with 20-nuclearity ([(MoO42-)@Ag20(C≡CtBu)8(Ph2PO2)7(tfa)2]·(tfa-) (1)) and 18-nuclearity ([(MoO42-)@Ag18(C≡CtBu)8(Ph2PO2)7]·(OH) (2)) (tfa = trifluoroacetate) were synthesized with the green light maximum emissions at 507 and 516 nm, respectively. The nanoclusters were investigated and characterized by single-crystal X-ray crystallography, electrospray ionization mass spectrum (ESI-MS), X-ray photoelectron spectroscopy, thermogravimetry (TG), photoluminescence (PL), ultraviolet-visible (UV-vis) spectroscopy, and density functional theory calculations (DFT). The two nanoclusters differ in their structure by a supplementary [Ag2(tfa)2] organometallic surface motif, which significantly participates in the frontier molecular orbitals of 1, resulting in similar bonding patterns but different optical properties between the two clusters. Indeed, both nanoclusters show strong temperature-dependent photoluminescence properties, which make them potential candidates in the fields of optical devices for further applications.

Investigating the effect of Zn doping and temperature on the photoluminescence behaviour of CuLaSe2 quantum dots.

In this study, CuLaSe2 and ZnCuLaSe2 quantum dots (QDs) with a mean size of ~4nm were synthesized and characterized, and their temperature-dependent photoluminescence (PL) properties were studied in the temperature range from 90 to 300 K for the first time. The results show that the obtained QDs were spherical and revealed excitonic band gaps. The PL intensity for both types of materials decreased when increasing the temperature to 300 K, which was attributed to the nonradiative relaxation and thermal escape mechanisms. As the temperature was increased, the PL linewidths broadened, and PL peak energies were red shifted for both types of QDs due to the exciton-phonon coupling and lattice deformation potential mechanisms. In addition, we found that as the temperature was decreased, the PL spectrum of ZnCuLaSe2 QDs contained two extra components, which could be attributed to the shallow defect sites (low energy peak) and the crystal phase transition process (high energy peak). The spectrum of CuLaSe2 QDs contained one extra component, which could be attributed to the crystal phase transition process.

Highly bright solid-state carbon dots for efficient anticounterfeiting.

Carbon dots (C-dots) as promising fluorescent materials have attracted much attention because of their low toxicity and excellent optoelectronic properties. However, the aggregation-caused quenching (ACQ) of the solid-state C-dots has limited their potential applications in anti-counterfeiting and optoelectronic devices. In this work, C-dot powder was prepared by directly dispersing the as-prepared C-dots in a polymer matrix or in situ formation of the C-dot/Ca-complex by vacuum heating in the presence of boric acid. The as-prepared C-dots have high quantum yields (QYs) in the range of 40-67% with temperature-dependent photoluminescent (PL) properties. As a proof of concept, the as-synthesized C-dots were used to produce a flexible anti-counterfeiting code and showed high-level security. This highlights the potential of C-dots in solid-state information, anti-information encryption and anti-counterfeiting.

Morphology does not matter: WSe2 luminescence nanothermometry unravelled.

Transition metal dichalcogenides, including WSe2, have gained significant attention as promising nanomaterials for various applications due to their unique properties. In this study, we explore the temperature-dependent photoluminescent properties of WSe2 nanomaterials to investigate their potential as luminescent nanothermometers. We compare the performance of WSe2 quantum dots and nanorods synthesized using sonication synthesis and hot injection methods. Our results show a distinct temperature dependence of the photoluminescence, and conventional ratiometric luminescence thermometry demonstrates comparable relative thermal sensitivity (0.68-0.80% K-1) and temperature uncertainty (1.3-1.5 K), irrespective of the morphology of the nanomaterials. By applying multiple linear regression to WSe2 quantum dots, we achieve enhanced thermal sensitivity (30% K-1) and reduced temperature uncertainty (0.1 K), highlighting the potential of WSe2 as a versatile nanothermometer for microfluidics, nanofluidics, and biomedical assays.

Multi-strategy ratiometric luminescent thermometry based on Dy doped CaWO4 phosphors independent of excitation wavelength

This paper explores the detailed photoluminescence (PL) behaviors of Dy3+ doped CaWO4 (Dy:CaWO4) phosphors under multi-ultraviolet wavelength excitation. Moreover, it proposes multi-strategy ratiometric thermometry based on luminescence intensity ratio (LIR) from the transitions of thermally coupled energy levels (TCLs) of Dy3+. Under excitation of multiple ultraviolet wavelengths, the Dy:CaWO4 phosphors exhibited multi-wavelength responsive PL characteristics of Dy3+ with strong blue and yellow emissions from Dy3+ TCLs transitions. The temperature-dependent PL properties of Dy:CaWO4 phosphors were investigated over a temperature range of 300∼650 K. Multi-strategy ratiometric luminescent thermometry was examined under various excitation wavelengths by the thermal equilibrium population of Dy3+ TCLs. The proposed six LIR schemes based on the PL emissions of Dy3+ exhibited a good quantitative relationship with temperature. They showed well-luminescent thermometric behaviors with high absolute and relative sensitivities due to the largest energy gap of TCLs and a relatively larger LIR value. The thermometry properties of the multiple LIR schemes were independent of excitation wavelength, attributed to the stable site symmetry of Dy3+ and the thermal equilibrium population of TCLs under different excitation wavelengths. The multi-strategy ratiometric thermometry of Dy3+ demonstrated the merit of high sensitivity, excellent stability, and repeatability, indicating the potential luminescent thermometric application of Dy:CaWO4 phosphors.

Energy transfer-based color tunability, thermal quenching, and quantum yield of Sm3+/Eu3+ codoped lithium zinc borophosphate glasses

Lithium zinc borophosphate (LZBP) glasses, imbedded with Sm3+, Eu3+, & Sm3+/Eu3+ ions in solely and combinedly were synthesized using melt-quenching technique, and their energy-transfer-dependent photoluminescence (PL)-related characteristics were explored. LZBP: 0.5 % Sm3+ and LZBP: 0.5 % Eu3+ glasses exhibited intense orange and red emissions under 404 and 394 nm excitation wavelengths, respectively. When the Sm3+/Eu3+ codoped glass systems were excited with Sm3+ excitation (404 nm), has lead to a noticeable drop in the emission intensity of Sm3+ peaks at 562 nm (4G5/2 → 6H5/2; yellow), 602 nm (4G5/2 → 6H7/2, orange), and 645 nm (4G5/2 → 6H9/2, red) whereas the emission intensity of Eu3+ peaks at 591 nm (5D0→7F1; orange) and 617 nm (5D0→7F2; red) has enhanced. At the same time, the decay lifetime of singly doped Sm3+ decreased from 1.54 to 0.91 ms, with codoping different concentrations of Eu3+ ions. The decrease in both PL intensity and lifetimes of Sm3+ in the presence of Eu3+ suggests an efficient energy transfer (ET) from Sm3+→Eu3+, which is facilitated by dipole-dipole interaction. The ET from Sm3+→Eu3+ achieved through the channels, Sm3+:4G5/2 + Eu3+:7F1 → Sm3+:6H7/2 + Eu3+:5D0 and Sm3+:4G5/2 + Eu3+:7F2 → Sm3+:6H5/2 + Eu3+:5D1. Furthermore, ET from Sm3+ to Eu3+ is supported by the spectral overlay between Sm3+ emission and Eu3+ absorption, ET parameters (η(Sm3+⟶Eu3+) = 40.91 % and P(Sm3+⟶Eu3+) = 1098.9 S-1). The shift in color coordinated from orange to red, with an increase in Eu3+ doping content in the codoped glasses at 404 nm excitation demonstrates the promising application of the Sm3+/Eu3+ codoped glass system in orange-red light-emitting diodes. LZBP: 0.5 Sm3+/1.0 Eu3+ codoped glass exhibited good thermal stability (Ea = 0.19 eV), depending on temperature-dependent PL properties. The quantum yield (η) for the LZBP glass containing 0.5 Sm3+/1.0 Eu3+ codoped ions is evaluated to be 44.6 %.

Photophysical properties of nitrogen-doped carbon quantum dots synthesized by graphite

Here, nitrogen-doped carbon quantum dots (N-CQDs) were successfully synthesized by the solvothermal method using graphite as the carbon source and N,N-dimethylformamide as the nitrogen source. We characterized the structure and chemical constitution of N-CQDs using X-ray diffraction, Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. We investigated the pump- and temperature-dependent photoluminescence (PL) properties and the dynamic exciton recombination processes of N-CQDs, using both steady-state and time-resolved PL techniques. The spectral results show that the PL emission peak located at 518 nm at room temperature, mainly originates from the n-π∗ transition on the surface of N-CQDs. The pump fluence and PL integral intensity were analyzed to demonstrate the existence of single-photon excitation under the 405 nm laser excitation. As the temperature increases, the non-radiative transition gradually increases, which decreases the PL intensity, the full width at half maxima first narrows and then widens and the PL lifetime gradually decreases. Furthermore, we combined the N-CQDs with chip to prepare light-emitting diode (LED). The resulting chromaticity coordinate was obtained to be (0.29, 0.40). This study offers a comprehensive understanding of the luminescence mechanism in N-doped CQDs and introduces a novel approach for the quickly fabrication of full-color display LEDs.

Studies on organic-mediated synthesis of Y2O3:Eu3+ nanophosphors and its temperature-dependent photoluminescence properties

Studies on organic-mediated synthesis of Y2O3:Eu3+ nanophosphors and its temperature-dependent photoluminescence properties

Temperature-dependent photoluminescence properties of single defects in AlGaN micropillars

Single-photon emitters (SPEs) are attractive as integrated platforms for quantum applications in technologically mature wide-bandgap semiconductors since their stable operation at room temperature or even at high temperatures. In this study, we systematically studied the temperature dependence of the SPE in AlGaN micropillar by experiment. The photoluminescence (PL) spectrum, PL intensity, radiative lifetime and second-order autocorrelation function measurements are investigated over the temperature range from 303 to 373 K. The point defects of AlGaN show strong zero phonon line in the wavelength range of 800–900 nm and highly antibunched photon emission even up to 373 K. Our study reveals a possible mechanism for linewidth broadening in AlGaN SPE at high temperatures. This indicates a possible key for on-chip integration applications based on this material operating at high temperatures.

Polar-Solvent-Free Sonochemical Synthesis of Mn(II)-Doped CsPbCl3 Perovskite Nanocrystals for Dual-Color Emission

We present a facile, one-step, polar-solvent-free sonochemical synthesis of a series of Mn-doped CsPbCl3 perovskite nanocrystals (PNCs) by varying the Pb-to-Mn ratio, after which their structure, morphology, and temperature-dependent photoluminescence (PL) properties are investigated. The partial substitution of Pb2+ with Mn2+ in CsPbCl3 PNCs caused lattice contraction without affecting the morphology and structure. All Mn-doped PNCs exhibited dual-wavelength PL profiles, with a weak violet band at around 410 nm attributed to band-edge exciton and a strong orange band at around 596 nm attributed to Mn2+:4T1→6A1 transition, benefited by the exciton-to-Mn2+ energy transfer. Furthermore, Mn doping increased the PL quantum yield (PLQY) from 5.1% in CsPbCl3 to 41.14% for 11.8% Mn-doped PNCs as well as decay lifetimes from nanoseconds to milliseconds (long-lived emissive states). Owing to the thermally assisted transition from the exciton to 4T1 energy level of Mn2+, the temperature-dependent steady-state PL and time-resolved PL spectra of exciton and Mn2+ in Mn-doped CsPbCl3 PNCs displayed unusual and contradictory trends. The ultrasonication synthesized Mn-doped PNCs exhibited superior long-term stability, retaining 62% (@ RH 75%) of the initial PL without requiring additional encapsulation. To evaluate the suitable application of Mn-doped CsPbCl3 PNCs in the white light-emitting diode (w-LED) as a display system, we built a prototype w-LED using blue-, green-, and orange-emitting CsPb(Cl0.5/Br0.5)3, CsPbBr3, and Mn-doped CsPbCl3-coated glass slices onto a 20 mA UV LED chip. The constructed prototype w-LED generated bright white light, achieving a luminous efficiency of 76.3 lm/W, color rendering index of 81.4, R9 of 80.1, and a wide color gamut of 101.78% NTSC and 76% BT-2020, demonstrating its promising application in w-LEDs.

Photoluminescence spectroscopy of Cr3+ in β-Ga2O3 and (Al0.1Ga0.9)2O3

Alloying β-Ga2O3 with Al2O3 to create (AlxGa1−x)2O3 enables ultra-wide bandgap materials suitable for applications deep into ultraviolet. In this work, photoluminescence (PL) spectra of Cr3+ were investigated in monoclinic single crystal β-Ga2O3, and 10 mol. % Al2O3 alloyed with β-Ga2O3, denoted β-(Al0.1Ga0.9)2O3 or AGO. Temperature-dependent PL properties were studied for Cr3+ in AGO and β-Ga2O3 from 295 to 16 K. For both materials at room temperature, the red-line emission doublet R1 and R2 occurs at 696 nm (1.78 eV) and 690 nm (1.80 eV), respectively, along with a broad emission band at 709 nm (1.75 eV). The linewidths for AGO are larger for all temperatures due to alloy broadening. For both materials, the R-lines blue-shift with decreasing temperature. The (lowest energy) R1 line is dominant at low temperatures due to the thermal population of the levels. For temperatures above ∼50 K, however, the ratio of R2 to R1 peak areas is dominated by nonradiative combination.

Study of concentration and temperature-dependent photoluminescence properties in DyF3-doped fluorophosphate glasses for thermal stable photonic device

The novel P2O5–ZnO–B2O3–Na2O–NaF multi-component fluorophosphate glasses doped with DyF3 were prepared via the conventional melt-quenching process. The effects of DyF3 concentration on the glass structure and photoluminescence properties were systematically discussed. The J-O analysis and radiative properties of Dy3+ ions in fluorophosphate glass were investigated. Upon the excitation of 349 nm, the fluorescence intensity of 4F9/2 → 6HJ/2 (J = 15, 13, 11, 9) transitions increase first and then decrease with the DyF3 concentration, and the optimum concentration was determined to be 1.5 mol%. The 1.5 mol% DyF3-doped glass exhibit a high photoluminescence quantum yield (54.65%) and great thermal stability. Finally, the temperature-dependent emission spectra contour map reveals that the fluorescence emission of the fluorophosphate glass with 1.5 mol% DyF3 demonstrates a downtrend with the temperature, and the fluorescence intensity of the yellow emission transition (4F9/2 → 6H13/2) at 473 K can still maintain 70% of that at the initial condition (298 K). These results suggest that these DyF3-doped fluorophosphate glasses may be applied for thermal stable photonic devices.

Temperature-Dependent Photoluminescence of CdS/ZnS Core/Shell Quantum Dots for Temperature Sensors.

Exploring the temperature-dependent photoluminescence (PL) properties of quantum dots (QDs) is not only important for understanding the carrier recombination processes in QD-based devices but also critical for expanding their special applications at different temperatures. However, there is still no clear understanding of the optical properties of CdS/ZnS core/shell QDs as a function of temperature. Herein, the temperature-dependent PL spectra of CdS/ZnS core/shell QDs were studied in the temperature range of 77-297 K. It was found that the band-edge emission (BEE) intensity decreases continuously with increasing temperature, while the surface-state emission (SSE) intensity first increases and then decreases. For BEE intensity, in the low temperature range, a small activation energy (29.5 meV) in the nonradiative recombination process led to the decrease of PL intensity of CdS/ZnS core/shell QDs; and at high temperature the PL intensity attenuation was caused by the thermal escape process. On the other hand, the temperature-dependent variation trend of the SSE intensity was determined by the competition of the trapping process of the surface trap states and the effect of thermally activated non-radiative defects. As the temperature increased, the PL spectra showed a certain degree of redshift in the peak energies of both band-edge and surface states and the PL spectrum full width at half-maximum (FWHM) increases, which was mainly due to the coupling of exciton and acoustic phonon. Furthermore, the CIE chromaticity coordinates turned from (0.190, 0.102) to (0.302, 0.194), which changed dramatically with temperature. The results indicated that the CdS/ZnS core/shell QDs are expected to be applied in temperature sensors.

A novel K3WO2F5·2H2O:Mn4+ phosphor with excellent hydrophobic stability by coating paraffin wax for the application of WLEDs

Novel narrow-band red-emitting K3WO2F5·2H2O:Mn4+ and its paraffin wax (PW)-coated phosphor (K3WO2F5·2H2O:Mn4+@PW) were synthesized via simple co-precipitation method. Optical properties of the phosphors have been systematically analyzed. Meanwhile, the energy transfer process in the phosphor was discussed in detail, which provides a feasible basis for broadening the application range of the phosphor when excited by UV-light. The thermostability of K3WO2F5·2H2O:Mn4+ sample was analyzed via investigating the temperature-dependent photoluminescence properties. More importantly, the luminescence properties and hydrophobic stability of the phosphors coated with PW were superior to those of K3WO2F5·2H2O:Mn4+ and K2SiF6:Mn4+. The luminescence intensity of K3WO2F5·2H2O:Mn4+@PW decreased by only 24.5% after the phosphor was immersed in water for 360 min. K3WO2F5·2H2O:Mn4+@PW was used as red component to fabricate the warm white light-emitting diode, which presents excellent photoelectric parameters Ra = 90.1 and CCT = 3664 K) and remarkable stability in the range of 20–200 mA driving current. These results demonstrated that K3WO2F5·2H2O:Mn4+@PW red composition has the ideal application value in WLEDs.

Rare-earth-free Mn4+ ions activated Ba2YSbO6 phosphors for solid-state lighting, flexible display, and anti-counterfeiting applications

Recenlty, rare-earth (RE)-free ions (Mn4+) activated phosphor materials are becoming an alternative source while replacing Eu2+ ions activated metal oxide, phosphate, and nitride phosphors for multi-functional applications. In this report, we prepared novel RE-free Mn4+ (mol%) ions activated double perovskite-type Ba2YSbO6 (BYSO:Mn4+) phosphor materials by a solid-state reaction method in an ambient condition. The physicochemical properties such as phase purity, elemental composition, and morphology of the materials were systematically investigated. The temperature-dependent photoluminescence (PL) properties of the BYSO:8 mol% Mn4+ (i.e., BYSO:8Mn4+) phosphor samples were studied. The PL excitation of the phosphors showed a broadband spectrum in the near-ultraviolet region from 300 to 450 nm with a maximum intensity at 353 nm. Under 353 nm excitation, the Mn4+ ions activated phosphors showed a broadband far-red emission in the region of 650–750 nm with a maximum intensity at 694 nm due to the 2Eg→4A2g electronic configuration. The BYSO:8Mn4+ phosphors also showed a lower intensity band at 667 nm and the corresponding Commission Internationale de l’Eclairage chromaticity coordinate for the optimized phosphor was (0.653, 0.274) which is more beneficial, especially for the growth process in plants. Additionally, the optimized BYSO:8Mn4+ phosphor maintained good thermal PL behavior and its related binding energy value was 0.29 eV. Considering these good benefits from the BYSO:8Mn4+ phosphor, we further fabricated a red light-emitting device to demonstrate its potential applicability in solid-state lighting. Also, the as-prepared polydimethylsiloxane composite films demonstrated their suitability for flexible display and anti-counterfeiting applications in harsh environmental conditions.

Temperature-dependent photoluminescence of Co-evaporated MAPbI3 ultrathin films

The hybrid organic–inorganic perovskite (PVK) thin films have attracted amounts of interest in the past decade due to the thickness-depended quantum confinement effects and tunable band gap as well as the demands of device miniaturization. Vacuum deposition is a promising method to realize precise control of film thickness and composition, low-temperature processing, the good compatibility with dry processing and compatible with the modern silicon-based semiconductor industry. Here, we report on the temperature-dependent photoluminescence properties of MAPbI3 ultrathin films with long-term stability and high quality fabricated by the co-evaporation. XPS, AFM and XRD results reveal that an excess MAI vapor environment plays a key role in sample preparation. PL is more sensitive than XPS to detect trace MAPbI3-like materials with strong luminescence properties. Temperature- dependent PL measurements show that the bandgap of MAPbI3 films red-shifted with the temperature decreasing in the range from 298 to 78 K, which is opposite to that of the traditional semiconductors and can be attributed to the interaction between the electron–phonon and the thermal expansion induced band gap renormalization. Gradual phase transition from tetragonal one to orthorhombic one is observed to start between 108 and 118 K, which is lower than the reported sudden phase transition temperature of 150 K for bulk MAPbI3 and suggests the important role of quantum confinement in ultrathin films. Our findings provide a way to fabricate PVK ultrathin films with long-term stability for novel light emitting devices.