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Iodine Induced PbI <sub/>2</sub> Porous Morphology Manipulation for High-Performance Planar Perovskite Solar Cells
摘要： The quality of the perovskite film has a vital influence on the performance of perovskite solar cells and it is quite desirable to simultaneously manipulate the crystallization and morphology of the perovskite film. In this study, conventional PbI2 is replaced with a PbI2/I2 mixed precursor during the first step of sequential deposition, causing the formation of a PbI2 porous nanostructure. By changing the content of I2 in the precursor, the morphology of the PbI2 film as well as the resulting perovskite film can be successfully modulated. With an optimal content of I2, a high-quality perovskite film with a pure phase and smooth surface can be achieved. As a result, the conversion efficiency of perovskite solar cells using a PbI2/I2 mixed precursor can be as high as 18.63%, compared to 16.89% for the reference device through traditional sequential deposition with a pure PbI2 precursor.
关键词： porous PbI2,iodine,perovskite,sequential deposition,solar cell
更新于2025-11-20 15:33:11
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High-Performance Photoresistors Based on Perovskite Thin Film with a High PbI2 Doping Level
摘要： We prepared high-performance photoresistors based on CH3NH3PbI3 ?lms with a high PbI2 doping level. The role of PbI2 in CH3NH3PbI3 perovskite thin ?lm was systematically investigated using scanning electron microscopy, X-ray diffraction, time-resolved photoluminescence spectroscopy, and photoconductive atomic force microscope. Laterally-structured photodetectors have been fabricated based on CH3NH3PbI3 perovskite thin ?lms deposited using precursor solution with various CH3NH3I:PbI2 ratios. Remarkably, the introduction of a suitable amount of PbI2 can signi?cantly improve the performance and stability of perovskite-based photoresistors, optoelectronic devices with ultrahigh photo-sensitivity, high current on/off ratio, fast photo response speed, and retarded decay. Speci?cally, a highest responsivity of 7.8 A/W and a speci?c detectivity of 2.1 × 1013 Jones with a rise time of 0.86 ms and a decay time of 1.5 ms have been achieved. In addition, the local dependence of photocurrent generation in perovskite thin ?lms was revealed by photoconductive atomic force microscopy, which provides direct evidence that the presence of PbI2 can effectively passivate the grain boundaries of CH3NH3PbI3 and assist the photocurrent transport more effectively.
关键词： grain boundary passivation,PC-AFM,photoresistor,high PbI2 doping content
更新于2025-11-14 15:28:36
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Investigation of the effect of MAI and PbI$$_{\mathrm {2}}$$2 concentrations on the properties of perovskite solar cells
摘要： the effect of perovskites layer quality on the performance of compact-TiO2/mesoporous-TiO2/CH3NH3PbI3/carbon solar cells was investigated. Different perovskite layers were prepared by varying concentrations of PbI2 and CH3NH3I, while reaction temperature and dipping time were ?xed. The range of concentrations for PbI2 and methylammonium iodide (MAI) were 1–1.4 M and 6–10 mg ml?1, respectively. Fabricated perovskite layers were ?rst coated by carbon electrodes (5-layer) and then, the champion one was coated by Spiro-OMeTAD (as a hole transport material) and Au-evaporated layer as a cathode (6-layer). Fabricated ?lms were fully characterized by ?eld emission scanning electron microscopy, X-ray diffraction analysis, UV–Vis spectroscopy and photoluminescence spectrum. Photovoltaic properties were measured under AM 1.5. Output currents of 5-layer cells were in the range of 228–476 μA, of which the highest one was obtained by using 1.2 M PbI2 and 8 mg ml?1 MAI. Ultimately, the maximum power conversion ef?ciency of 9.1% was obtained with 6-layer cell.
关键词： solar cell,MAI,Perovskite layer,PbI2,optimization
更新于2025-09-23 15:19:57
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Visible-enhanced silver-doped PbI2 nanostructure/Si heterojunction photodetector: effect of doping concentration on photodetector parameters
摘要： This paper presents the effect of doping concentration on the properties of PbI2 nanostructure film and p-PbI2:Ag/n-Si photodetector prepared by pulsed laser deposition PLD method. The PbI2 film was doped with silver at doping concentrations of 1%, 3% and 5%. XRD results show that all deposited PbI2 films are polycrystalline and well-crystallized along (001) plane with hexagonal structure. The structural studies revealed that the grain size of the film decreases as the doping concentration increase. Energy dispersive X-ray EDX, scanning electron microscope SEM and elemental mapping analysis confirm the presence of Pb, I and Ag elements and the films were near stoichiometric. Raman spectra of PbI2 film showed the presence of Raman peaks located at 73, 94.3, 108, 165.7, and 208.9 cm?1 corresponding to E2 vibration modes, respectively, and a Raman peak at 185 cm?1 was observed for the film doped with 5 wt% which indexed to 2E1. The optical energy gap of the film decreased from 2.8 to 2.3 eV after doping with silver. Hall measurement confirms that the deposited PbI2 films are p-type and the electrical resistivity of the film increases from 1.1 × 104 to 1.8 × 107 ? cm as doping concentration increases from 1 to 5%.
关键词： PLD,Raman spectra,2H-polytype,PbI2,Photodetector,Ag:PbI2
更新于2025-09-19 17:13:59
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Ligand-Modulated Excess PbI <sub/>2</sub> Nanosheets for Highly Efficient and Stable Perovskite Solar Cells
摘要： Excess lead iodide (PbI2), as a defect passivation material in perovskite films, contributes to the longer carrier lifetime and reduced halide vacancies for high-efficiency perovskite solar cells. However, the random distribution of excess PbI2 also leads to accelerated degradation of the perovskite layer. Inspired by nanocrystal synthesis, here, a universal ligand-modulation technology is developed to modulate the shape and distribution of excess PbI2 in perovskite films. By adding certain ligands, perovskite films with vertically distributed PbI2 nanosheets between the grain boundaries are successfully achieved, which reduces the nonradiative recombination and trap density of the perovskite layer. Thus, the power conversion efficiency of the modulated device increases from 20% to 22% compared to the control device. In addition, benefiting from the vertical distribution of excess PbI2 and the hydrophobic nature of the surface ligands, the modulated devices exhibit much longer stability, retaining 72% of their initial efficiency after 360 h constant illumination under maximum power point tracking measurement.
关键词： PbI2,perovskite solar cells,ligand modulation
更新于2025-09-19 17:13:59
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Bulk recrystallization for efficient mixed-cation mixed-halide perovskite solar cells
摘要： Today, the use of mixed-cation lead mixed-halide perovskite with a slight excess of lead iodide (PbI2) demonstrates the highest device performances in the literature. However, the presence of excess PbI2 in the film poses long-term stability concerns. Here, we propose a facile bulk recrystallization process by applying formadinium chloride (FACl) on perovskite to remove excess PbI2 in the formed crystal. We are able to demonstrate bulk recrystallization, proved and observed by the Grazing incidence XRD to analyze the crystal structure as a function of depth profiling. The reconstructed crystal displays improved optoelectronic qualities with reduced interfacial recombination as well as enhanced device stability. When measured under AM 1.5G spectral conditions the optimized champion device reached a maximum power conversion efficiency (PCE) of 20.2%.
关键词： bulk recrystallization,optoelectronic qualities,FACl,perovskite solar cells,PbI2,device stability
更新于2025-09-16 10:30:52
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Off-Stoichiometric Methylammonium Iodide Passivated Large Grain Perovskite Film in Ambient Air for Efficient Inverted Solar Cells
摘要： Hot-casting is a promising technique in deposition high-quality organic-inorganic hybrid perovskite thin films with large crystal grain size. Here we reported the crystallinity and grain size of perovskite films could be systematically tailored by modulating the stoichiometry of the precursor solution in hot-casting process under ambient condition with a relative humidity of 40%. It was found that a slight excess of methylammonium iodide (MAI) in the precursor solution could effectively compensate the MAI loss due to the high substrate temperature. A significant increase in grain size and crystallinity of the perovskite film was observed together with a decrease in defect density and a carrier concentration enhancement in the MAI-rich samples. The corresponding devices exhibited a notable increase in fill factor (up to 80.7%) and short-circuit current density. In addition, in MAI-deficient samples, an enrichment of PbI2 at the grain boundaries was directly observed by optical microscopy and laser confocal microscopy. Time-resolved photoluminescence spectroscopy revealed an increase in the charge carrier lifetime in the MAI-deficient samples, which was in line with the previous results with a small amount of excess PbI2 in the perovskite film. This work highlights a new strategy to prepare high-quality perovskite thin films with excellent crystal quality under ambient condition.
关键词： PbI2 enrichment,excess MAI,humidity,Hot-casting
更新于2025-09-16 10:30:52
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Mechanism of PbI2 situ-passivated perovskite films for enhancing performance of perovskite solar cells
摘要： Perovskite solar cells have brought tremendous research interests because of their tolerance of defects, low cost, and facile processing. In perovskite solar cells devices, PbI2 has been utilized to passivate defects at perovskite films surface and grain boundaries, yet a systematic mechanism of PbI2 situ-passivating for enhancing the efficiency has not been fully explored. Here, this work systematically studies the role of the precise PbI2 ratio, and the PbI2 situ-passivation mechanism based on trap density, carrier lifetime, and Fermi level etc. This study finds that the appropriate ratio of I:Pb is around 2.57:1 using energy dispersive spectroscopy. After the moderate excess PbI2 situ-passivating, the trap density is reduced from 6.12 × 1016 cm-3 to 3.38 × 1016 cm-3, and the carrier lifetime is extended from 168.35 ps to 368.77 ps by using femtosecond transient absorption spectroscopy. This result indicates that the moderate excess PbI2 situ-passivation can reduce the trap density and suppress non-radiative recombination. The efficiency of solar cell has realized a nearly 11.3% improvement of 19.55% for the I:Pb ratio of 2.57:1 compared with 2.69:1. It demonstrates that the efficiency can be enhanced effectively by PbI2 situ-passivation.
关键词： SnO2,EDS-mapping,transient absorption spectroscopy,perovskite solar cells,PbI2,passivation mechanism
更新于2025-09-12 10:27:22
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Improved growth conditions of pulsed laser-deposited PbI2 nanostructure film: towards high- photosensitivity PbI2/CNTs/Si photodetectors
摘要： Nanostructured PbI2 films were grown by laser deposition technique at a substrate temperature of 45?°C was demonstrated. Herein, we attempted to improve and control the crystal growth of PbI2 film and p-PbI2/MWCNTs/p-Si photodetector by finding the optimum laser fluence. X-ray diffraction XRD results illustrate that the grown PbI2 films are polycrystalline with hexagonal structure along (001) and the film crystallinity degraded with increasing the laser fluence. Scanning electron microscope SEM revealed that the particle size decreases as laser fluence increase and film deposited at 3.9?J/cm2 was dense and the grains distributed uniformly over the surface of the film. Energy dispersive X-ray EDX data confirms that the film stoichiometry depends on laser fluence and the film deposited at 3.9?J/cm2 was stoichiometric PbI2. The Photosensitivity investigations reveal that responsivity as high as 0.4 A/W at 610?nm was obtained for the p-PbI2/MWCNTs/p-Si photodetector prepared at 3.9?J/cm2 without post-deposition annealing.
关键词： photodetector,nanostructure film,PbI2,pulsed laser deposition,laser fluence
更新于2025-09-12 10:27:22
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Preparation of visible-enhanced PbI2/MgO/ Si heterojunction photodetector
摘要： Fabrication and characterization of p-PbI2/MgO/n-Si photodetectors by pulsed laser deposition within (2.7-2.5) eV. The current-voltage and capacitance-voltage properties of PbI2/MgO/Si photodetector were investigated. The best responsivity of p-PbI2/MgO/n-Si photodetectors was ~ investigated using x-ray diffraction XRD, UV-Vis absorption and scanning electron microscope SEM. The XRD results revealed a single crystalline MgO with cubic structure along the (200) PLD under different deposition temperatures Ts were demonstrated for the first time. Structural, optical and morphological properties of nanostructured MgO and PbI2/MgO films were plane, while the PbI2 film deposited on MgO was a single crystalline with hexagonal phase along (001) plane. The optical energy gaps of PbI2 films deposited on MgO film were found to be perovskite solar cells, photodetectors, X-ray detectors, photoconductors, biological labeling and diagnostics, active matrix flat panel imagers, and γ-ray detectors [3, 4]. PbI2 films are usually prepared thermal evaporation, chemical methods, pulsed laser deposition, atomic layer deposition, and electron beam evaporation [5-8]. The wider optical energy gap MgO (7.3 eV at room temperature) is a non-toxic, high specific surface reactivity and cubic crystal structure with Fm-3m space group and transparent at the visible light. MgO films have been used in many [1, 2]. Lead iodide has been used in numerous applications, for example, light emitting diodes, Lead iodide has a hexagonal structure with optical band gap around 2.2eV at room temperature Keywords: PbI2; MgO; PLD; Heterojunction; Silicon; photodetector; Deposition temperature 0.88A/W at 410nm when the photodetector was prepared at Ts = 45°C.
关键词： Silicon,photodetector,MgO,Deposition temperature,PbI2,Heterojunction,PLD
更新于2025-09-11 14:15:04