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Stable luminescence of CsPbBr3/nCdS core/shell perovskite quantum dots with Al self-passivation layer modification
摘要： Perovskite quantum dots (PQDs) are among the most important luminescent semiconducting materials; however, they are unstable. Exposure to light, heat, and air can lead to irreversible degradation, which results in fluorescence quenching. Therefore, defects in PQDs significantly limit their practical application. Herein we describe a simple method to enhance the photostability of CsPbBr3/nCdS QDs, which involves doping their shells with aluminum. The temperature-dependent photoluminescence (PL) of colloidal CsPbBr3/nCdS/Al2O3 QDs is investigated, and the thermal quenching of PL, blueshift of the optical bandgap, and PL linewidth broadening are observed in each QD sample. Al2O3 layers on the CsPbBr3/nCdS QDs can effectively prevent photodegradation. Nonlinear, temperature-dependent exciton-phonon coupling and lattice dilation leads to radiative and non-radiative relaxation processes at temperatures ranging from 10 to 300 K; moreover, changes in the bandgap and PL spectral line broadening are observed.
关键词： quantum dots,Al layer,photoluminescence,Temperature-dependent PL,CsPbBr3/nCdS
更新于2025-09-16 10:30:52
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Efficient CsPbBr3 Inorganic Perovskite Light-Emitting Diodes via Lewis Acid-Base Reaction with Organic Small Molecule mCP
摘要： CsPbBr3 all-inorganic perovskite light-emitting diodes (PeLEDs) have received increasing attention in recent years due to their unique luminescent property and superior thermal stability. However, the low solubility of bromide precursors and the fast crystallization of perovskites usually cause the formation of discontinuous CsPbBr3 films with rough grains and large pin-holes. This would increase the defects and non-radiative recombination and severely degrade the device electroluminescence (EL) performance. To tackle this issue, herein, the 1,3-bis9H-carbazol-9-ylbenzene (mCP) small molecule was elaborately selected as an effective additive to enhance the film-forming ability of CsPbBr3 emissive layers. With the addition of mCP, the submicron-sized CsPbBr3 grains were reduced to nanometer range, and the resulting perovskite films became uniform and continuous. It was found that the electron pairs of N2- in mCP would donate to metal Pb2+ in CsPbBr3. Thus the so-called Lewis acid-base reaction occurred, which could retard the fast crystallization process and contribute to the connection of perovskite grains. As such, the film roughness was decreased from 8.28 nm to 1.62 nm, and the carrier lifetime was increased from 2.49 ns to 68.39 ns. The CsPbBr3:mCP device with an optimized mass ratio of 1:0.10 exhibited a maximum luminance (L) of 21008 cd/m2, a maximum current efficiency (CE) of 3.74 cd/A, and the corresponding maximum external quantum efficiency (EQE) of 1.21%, far surpassing the EL performance of the pristine CsPbBr3 PeLEDs.
关键词： Organic small molecule mCP,Effective additive,CsPbBr3 inorganic perovskite,Lewis acid-base reaction,Light-emitting diodes
更新于2025-09-16 10:30:52
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Fluorescence resonance energy transfer effect enhanced high performance of Si quantum Dots/CsPbBr3 inverse opal heterostructure perovskite solar cells
摘要： CsPbBr3 based perovskite solar cells draw boosted investigation benefitting from their simplified preparation property and outstanding stability against moist and heat while the photo-electrical conversion efficiency (PCE) is still worth promotion. In addition, relatively wide band gap limits the light utilization ability of pristine CsPbBr3 which leads to insufficient photo-induced charge carrier population thereby a low photocurrent density. Herein, we for the first time demonstrate a strategy to combine crystalized Si quantum dots (QDs) with CsPbBr3 inverse opal (IO) which significantly enhances the solar energy utilization efficiency by virtue of providing an additional fluorescence resonance energy transfer (FRET) process from Si QDs to CsPbBr3 IO. Acting as donor, the emitted photoluminescence from Si QDs can be absorbed by CsPbBr3, which serves as acceptor, leading to an increased carrier population in the system. Meanwhile, the multi-dimensional heterojunction between Si QDs and CsPbBr3 IO effectively facilitates the system bulk charge transfer process. A greatly improved PCE up to 8.31% with an obviously enhanced photocurrent density up to 7.8 mA?cm?2 can be obtained with a competitive IPCE up to 81%. This strategy provides a new alternative method to develop high-performance perovskite solar cells and other photo-electronic devices.
关键词： Perovskite solar cells,CsPbBr3,Heterostructure,Fluorescence resonance energy transfer
更新于2025-09-16 10:30:52
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Evidence for Ferroelectricity of All-Inorganic Perovskite CsPbBr3 Quantum Dots
摘要： The ferroelectric-optical combination of properties in halide perovskites has attracted tremendous interests because of its potential for optoelectronic and energy applications. However, very few reports focus on the ferroelectricity of all-inorganic halide perovskites quantum dots. Herein, we report a excellent ferroelectricity in CsPbBr3 quantum dots (QDs) with a saturation polarization of 0.25 μC/cm2. Differential scanning calorimeter (DSC), X-ray diffraction (XRD), transmission electronic microscopy (TEM) revealed that the mechanism of ferroelectric-paraelectric switching of CsPbBr3 QDs can be attributed to the phase transition from cubic phase (????3??) to orthorhombic phase (Pna21). In the orthorhombic CsPbBr3, the distortion of octahedral [PbBr6]4- structural units and the off-center Cs+ generated the slightly separated centres of positive charge and negative charge, resulting in the ferroelectric properties. The variable temperature emission spectrum from 328 K to 78 K exhibits green luminescence and the gradually red shift due to the phase transition. This finding opens up a avenue to explore the ferroelectric-optical properties of inorganolead halide perovskites for high-performance multifunctional materials.
关键词： CsPbBr3 quantum dots,all-inorganic perovskite,phase transition,optoelectronic applications,ferroelectricity
更新于2025-09-16 10:30:52
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Sensitive Terahertz Free Space Modulator Using CsPbBr3 Perovskite Quantum Dotsa??Embedded Metamaterial
摘要： We have demonstrated a method for active modulating terahertz wave using CsPbBr3 perovskite quantum dots (QDs)–embedded double-C metallic metamaterial unit cells. The resonance response frequency of the proposed CsPbBr3 perovskite QDs-embedded metamaterial can be tuned by varying the external applied photoexcitation intensity. By doing so, we measured the dynamic terahertz wave transmission modulation and demonstrate tuning of the terahertz wave resonant response based on the optical pump fluences. The modulation speed and depth of the modulator are 5 MHz and 88.3%, respectively. Our results indicate the importance of manipulating the terahertz wave for future wireless communication.
关键词： Terahertz modulation,CsPbBr3 perovskites quantum dots,Terahertz wave
更新于2025-09-16 10:30:52
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Efficient and stable planar all-inorganic perovskite solar cells based on high-quality CsPbBr3 films with controllable morphology
摘要： All-inorganic cesium lead bromide (CsPbBr3) perovskite is attracting growing interest as functional materials in photovoltaics and other optoelectronic devices due to its superb stability. However, the fabrication of high-quality CsPbBr3 films still remains a big challenge by solution-process because of the low solubility of the cesium precursor in common solvents. Herein, we report a facile solution-processed approach to prepare high-quality CsPbBr3 perovskite films via a two-step spin-coating method, in which the CsBr methanol/H2O mixed solvent solution is spin-coated onto the lead bromide films, followed by an isopropanol-assisted post-treatment to regulate the crystallization process and to control the film morphology. In this fashion, dense and uniform CsPbBr3 films are obtained consisting of large crystalline domains with sizes up to microns and low defect density. The effectiveness of the resulting CsPbBr3 films is further examined in perovskite solar cells (PSCs) with a simplified planar architecture of fluorine–doped tin oxide/compact TiO2/CsPbBr3/carbon, which deliver a maximum power conversion efficiency of 8.11% together with excellent thermal and humidity stability. The present work offers a simple and effective strategy in fabrication of high-quality CsPbBr3 films for efficient and stable PSCs as well as other optoelectronic devices.
关键词： CsPbBr3,Morphology control,Stability,All-inorganic perovskite solar cells,Solution-processed
更新于2025-09-12 10:27:22
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Improvement of CsPbBr3 photodetector performance by tuning the morphology with PMMA additive
摘要： The optoelectrical properties of semiconductor devices are strongly related to the film morphology. Here, we found that, for CsPbBr3 thin films prepared by spray coating, the addition of polymethyl methacrylate (PMMA) can completely eliminate voids and greatly reduce the surface roughness of the as-deposited films. As a consequence, the optoelectronic properties of the photodetectors fabricated as a simple vertical structure of Au/CsPbBr3(PMMA)/ITO can be improved. With the addition of PMMA, the dark current of the photodetector is reduced at least four times, and the photodetector exhibits a favourable optical response. With the illumination ranging from 400 to 510 nm, the calculated responsivity varies from 3.70 to 5.20 A/W. A good response speed with a rise time of 6.6 ms and a decay time of 11.3 ms can be achieved. Moreover, unlike the inorganic-organic hybrid perovskite detectors, this inorganic perovskite photodetector without encapsulation shows a favourable stability with a decay of 20% after 40 days under ambient air at 20% humidity.
关键词： Photodetector,Spray coating,PMMA,Surface roughness,CsPbBr3
更新于2025-09-12 10:27:22
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Novel Bromide Quaternary Ammonium Ligand for Synthesizing High Fluorescence Efficiency CsPbBn Perovskite Quantum Dots and Their Fabrication of White Light-Emitting Diodes with Wide Color Gamut
摘要： We proposed a novel bromine quaternary ammonium ligand to synthesize high quantum yield (QY) CsPbBr3 quantum dots (QDs). The QY of CsPbBr3 QDs synthesized by this ligand reached 95% and the full width at half maximum (FWHM) was as narrow as 17nm. The peak wavelength of the prepared CsPbBr3 QDs was 530nm. And these QDs emitted high purity green light under ultraviolet light. The color coordinate of white LED (WLED) prepared with the CsPbBr3 QDs was (0.29, 0.31), which was very close to pure white light. The color gamut of the WLED covered 130% of the national television system committee (NTSC) color standard and 96% of the ITU-R Recommendation BT.2020 (Rec.2020) color standard.
关键词： CsPbBr3 Perovskite Quantum Dots,Bromide Quaternary Ammonium Ligand,Wide Color Gamut,White Light-Emitting Diodes
更新于2025-09-12 10:27:22
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Facile method for the preparation of high-performance photodetectors with a GQDs/perovskite bilayer heterostructure
摘要： A high-performance nitrogen doped graphene quantum dots (GQDs)/all-inorganic (CsPbBr3) perovskite nanocrystals (NCs) heterostructure photodetector was fabricated on a quartz substrate, using the low cost spin coating technique followed by hot plate annealing. The GQDs/CsPbBr3 NCs heterostructure photodetector exhibits a high overall performance with a photoresponsivity of 0.24 AW?1, on/off ratio of 7.2 × 104, and specific detectivity of up to 2.5 × 1012 Jones. The on/off ratio of the hybrid device was improved by almost ten orders of magnitude, and the photoresponsivity was enhanced almost three times compared to the single layer perovskite NCs photodetector. The performance enhancement of the hybrid device was due to its highly efficient carrier separation at the GQDs/CsPbBr3 NCs interface. This results from the coupling of the GQDs layer, which efficiently extracts and transports the photogenerated carriers, with the CsPbBr3 NCs layer, which has a large absorption coefficient and high quantum efficiency. The interfacial charge transfer from the CsPbBr3 NCs to the GQDs layer was demonstrated by the quenching in the photoluminescence (PL) spectra, and the fast-average decay time in the time-resolved photoluminescence (Trpl) spectra of the hybrid photodetector. Moreover, the performance-enhancement mechanism of the hybrid GQDs/CsPbBr3 photodetector was elucidated by analyzing the band alignment of the GQDs and CsPbBr3 under laser illumination.
关键词： Carrier separation,Charge transfer,CsPbBr3 nanocrystals,Photodetectors,Graphene quantum dots
更新于2025-09-12 10:27:22
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Fabrication of efficient CsPbBr3 perovskite solar cells by single-source thermal evaporation
摘要： It is promising to improve the stability of organic–inorganic hybrid halide perovskite solar cells by using all-inorganic perovskite materials. Herein, a facile one-crucible single-source vacuum thermal evaporation (VTE) approach is developed, which is used to evaporate two different melting points materials CsBr (630 °C) and PbBr2 (370.6 °C) to deposit high-quality inorganic CsPbBr3 perovskite films. Molar ratio of PbBr2 to CsBr in their mixture in the crucible is a key factor influencing the stoichiometry, structure, photoelectrical and photovoltaic properties of the CsPbBr3 films. The other important factor is the thickness of the CsPbBr3 films. High-quality CsPbBr3 films with good uniformity and compact and large grains are prepared. Planar CsPbBr3 perovskite solar cells are fabricated giving a high power conversion efficiency of 8.65%. The fabricated CsPbBr3 solar cells exhibit a good stability in air without encapsulation. This study opens up the possibility to deposit multi-element compound thin films by facile single-source VTE of different melting points materials.
关键词： Solar cells,Single-source evaporation,Thickness,Molar ratio,CsPbBr3 films
更新于2025-09-12 10:27:22