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- 实验方案
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Vacuum‐Assisted Growth of Low‐Bandgap Thin Films (FA <sub/>0.8</sub> MA <sub/>0.2</sub> Sn <sub/>0.5</sub> Pb <sub/>0.5</sub> I <sub/>3</sub> ) for All‐Perovskite Tandem Solar Cells
摘要： All-perovskite multijunction photovoltaics, combining a wide-bandgap (WBG) perovskite top solar cell (EG ≈1.6–1.8 eV) with a low-bandgap (LBG) perovskite bottom solar cell (EG < 1.3 eV), promise power conversion efficiencies (PCEs) >33%. While the research on WBG perovskite solar cells has advanced rapidly over the past decade, LBG perovskite solar cells lack PCE as well as stability. In this work, vacuum-assisted growth control (VAGC) of solution-processed LBG perovskite thin films based on mixed Sn–Pb perovskite compositions is reported. The reported perovskite thin films processed by VAGC exhibit large columnar crystals. Compared to the well-established processing of LBG perovskites via antisolvent deposition, the VAGC approach results in a significantly enhanced charge-carrier lifetime. The improved optoelectronic characteristics enable high-performance LBG perovskite solar cells (1.27 eV) with PCEs up to 18.2% as well as very efficient four-terminal all-perovskite tandem solar cells with PCEs up to 23%. Moreover, VAGC leads to promising reproducibility and potential in the fabrication of larger active-area solar cells up to 1 cm2.
关键词： vacuum-assisted growth control,all-perovskite tandem solar cells,solar cells,large grain,low-bandgap perovskites
更新于2025-09-12 10:27:22
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Modulation of Growth Kinetics of Vacuum-Deposited CsPbBr <sub/>3</sub> Films for Efficient Light-Emitting Diodes
摘要： Due to its excellent optical properties and good stability, all-inorganic halide perovskite CsPbX3 (X=I, Br, Cl) has been attracting interest for use in light-emitting diodes (LEDs). One challenge is improving the efficacy of the spatial confinement of excitons for higher luminescence efficiency. Here, we present a simple yet very effective strategy to form fine-grain-structured CsPbBr3 polycrystalline films prepared by thermal co-evaporation. The strategy involves controlling growth kinetics by adjusting the deposition flux which, along with growth temperature, determines the nucleation rate and therefore eventual grain structure. A correlation between deposition flux and average grain size was noted except for a very large deposition flux when there were large hillocks, which we attributed to the peculiar growth behavior of PbBr2 films. The growth conditions that produced a nano-scale grain structure and textured orientations without large hillocks also resulted in the highest luminescence efficiency as we anticipated. With the optimized CsPbBr3 light emitters, we demonstrate a green light-emitting (at 524 nm) LED with a maximum current efficiency of 1.07 cd/A and an extremely narrow electroluminescence spectrum of 18 nm, a result that highlights the potential of vacuum-processed CsPbBr3 films for high efficiency LEDs.
关键词： Light-emitting Diodes,Thermal co-evaporation,Perovskites,Vacuum deposition,LEDs,CsPbBr3
更新于2025-09-12 10:27:22
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Wide‐Bandgap Perovskite/Gallium Arsenide Tandem Solar Cells
摘要： Gallium arsenide (GaAs) photovoltaic (PV) cells have been widely investigated due to their merits such as thin-film feasibility, flexibility, and high efficiency. To further increase their performance, a wider bandgap PV structure such as indium gallium phosphide (InGaP) has been integrated in two-terminal (2T) tandem configuration. However, it increases the overall fabrication cost, complicated tunnel-junction diode connecting subcells are inevitable, and materials are limited by lattice matching. Here, high-efficiency and stable wide-bandgap perovskite PVs having comparable bandgap to InGaP (1.8–1.9 eV) are developed, which can be stable low-cost add-on layers to further enhance the performance of GaAs PVs as tandem configurations by showing an efficiency improvement from 21.68% to 24.27% (2T configuration) and 25.19% (4T configuration). This approach is also feasible for thin-film GaAs PV, essential to reduce its fabrication cost for commercialization, with performance increasing from 21.85% to 24.32% and superior flexibility (1000 times bending) in a tandem configuration. Additionally, potential routes to over 30% stable perovskite/GaAs tandems, comparable to InGaP/GaAs with lower cost, are considered. This work can be an initial step to reach the objective of improving the usability of GaAs PV technology with enhanced performance for applications for which lightness and flexibility are crucial, without a significant additional cost increase.
关键词： gallium arsenide,phase segregation,perovskite/GaAs tandem cells,thin-film flexible tandem cells,wide-bandgap perovskites
更新于2025-09-12 10:27:22
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Efficient All‐Solution‐Processed Perovskite Light‐Emitting Diodes Enabled by Small‐Molecule Doped Electron Injection Layers
摘要： Metal halide perovskites have attracted considerable attention in the field of light-emitting diodes due to their high color purity and solution processability. However, most perovskite light-emitting diodes (PeLEDs) employ thermally deposited charge transport layers (CTLs) on top of perovskite layers. In order to realize low-cost and scalable fabrication of PeLEDs, all-solution process is highly desired, but still remaining great challenges. Here, an efficient all-solution-processed green PeLEDs is reported by incorporating 1,3,5-tris(1-phenyl-1H-benzimidazol-2-yl)benzene (TPBi) doped conjugated amino-alkyl substituted polyfluorene poly[(9,9-bis(3′-(N,N-dimethylamino) propyl)-2,7-fluorene)-alt-2,7-(9,9-dioctylfluorene)] (PFN) electron injection layer, achieving a maximum luminance of 9875 cd m?2, a high current efficiency of 10.41 cd A?1, and an external quantum efficiency of 3.19%. Since the solvents used for perovskite precursors and PFN are orthogonal, the protected and complete interface of perovskite film and CTL is effectively obtained by solution processes. The doping of TPBi into PFN not only enhances the capability of electron injection, but also significantly suppresses the emission quenching of perovskite films caused by the charge transfer between perovskite and PFN due to the reduced difference in their work functions. This work provides an efficient approach for the development of all-solution-processed PeLEDs.
关键词： light-emitting diodes,all-solution-processed PeLEDs,electron injection layers,charge transfer,perovskites
更新于2025-09-12 10:27:22
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Modeling Thin Film Solar Cells: From Organic to Perovskite
摘要： Device model simulation is one of the primary tools for modeling thin film solar cells from organic materials to organic–inorganic perovskite materials. By directly connecting the current density–voltage (J–V) curves to the underlying device physics, it is helpful in revealing the working mechanism of the heatedly discussed organic–inorganic hybrid perovskite solar cells. Some distinctive optoelectronic features need more phenomenological models and accurate simulations. Herein, the application of the device model method in the simulation of organic and organic–inorganic perovskite solar cells is reviewed. To this end, the ways of the device model are elucidated by discussing the metal–insulator–metal picture and the equations describing the physics. Next, the simulations on J–V curves of organic solar cells are given in the presence of the space charge, interface, charge injection, traps, or exciton. In the perovskite section, the effects of trap states, direct band recombination, surface recombination, and ion migration on the device performance are systematically discussed from the perspective of the device model simulation. Suggestions for designing perovskite devices with better performance are also given.
关键词： perovskites,device models,thin film solar cells,organic semiconductors
更新于2025-09-12 10:27:22
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Light or Heat: What Is Killing Lead Halide Perovskites Under Solar Cell Operation Conditions?
摘要： We report the first systematic assessment of intrinsic photothermal stability of a large panel of complex lead halides APbX3 incorporating different univalent cations (A=CH3NH3+, [NH2CHNH2]+, Cs+) and halogen anions (X=Br, I) using a series of analytical techniques such as UV-vis and x-ray photoelectron spectroscopy, x-ray diffraction, EDX analysis, atomic force and scanning electron microscopy, ESR spectroscopy and mass spectrometry. We show that heat stress and light soaking induce a severe degradation of perovskite films even in the absence of oxygen and moisture. The stability of complex lead halides increases in the order MAPbBr3<MAPbI3<FAPbI3<FAPbBr3<CsPbI3<CsPbBr3, thus featuring all-inorganic perovskites as the most promising absorbers for stable perovskite solar cells. An important correlation was found between the stability of the complex lead halides and the volatility of univalent cation halides incorporated in their structure. The established relationship provides useful guidelines for designing new complex metal halides with immensely improved stability.
关键词： Plasmonics and Optoelectronics,Photothermal Stability,Solar Cell Operation Conditions,Energy Conversion and Storage,Lead Halide Perovskites
更新于2025-09-12 10:27:22
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Dark sub-gap states in metal-halide perovskites revealed by coherent multidimensional spectroscopy
摘要： Metal-halide perovskites show excellent properties for photovoltaic and optoelectronic applications, with power conversion efficiencies of solar cell and LEDs exceeding 20%. Being solution processed, these polycrystalline materials likely contain a large density of defects compared to melt-grown semiconductors. Surprisingly, typical effects from defects (absorption below the bandgap, low fill factor and open circuit voltage in devices, strong non-radiative recombination) are not observed. In this work, we study thin films of metal-halide perovskites CH3NH3PbX3 (X = Br,I) with ultrafast multidimensional optical spectroscopy to resolve the dynamics of band and defect states. We observe a shared ground state between the band-edge transitions and a continuum of sub-bandgap states, which extends at least 350 meV below the band edge). We explain the comparatively large bleaching of the dark sub-bandgap states with oscillator strength borrowing from the band-edge transition. Our results show that upon valence to conduction band excitation such sub-gap states are instantaneously bleached for large parts of the carrier lifetime and conversely, that almost dark sub-bandgap states can be populated by light excitation. This observation helps unraveling the photophysical origin of the unexpected optoelectronic properties of these materials.
关键词： photovoltaic,defect states,metal-halide perovskites,optoelectronic,ultrafast multidimensional optical spectroscopy
更新于2025-09-12 10:27:22
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Synergistic Improvements in Efficiency and Stability of 2D Perovskite Solar Cells with Metal Ion Doping
摘要： 2D perovskites hold a great prospective to create highly efficient and stable solar cell devices. In order to explore their full potential, every component of 2D perovskite solar cells (PSCs) has to be carefully designed and engineered. Herein, the metal ion doping strategy is taken to optimize both the hole transport layers (HTLs) and the light absorbing layers of the BA2MA3Pb4I13 (BA = butylamine; MA = methylammonium) based 2D PSC devices. The hole extraction and transport abilities are significantly enhanced by Cu ion doping in the nickel oxide layers, while the optoelectronic properties of the BA2MA3Pb4I13 layers are effectively improved with Cs ion doping. The synergistic incorporations of Cu and Cs ions have boosted the device power conversion efficiency to 13.92%, the highest for 2D PSCs based on inorganic HTLs. In addition, the inorganic nature of the Cu doped nickel oxide film and the high quality of the Cs doped 2D perovskite film also endow the PSC device with extraordinary humidity and thermal stabilities.
关键词： 2D perovskites,metal ion doping,stability,solar cells
更新于2025-09-12 10:27:22
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Impact of PbI <sub/>2</sub> Passivation and Grain Size Engineering in CH <sub/>3</sub> NH <sub/>3</sub> PbI <sub/>3</sub> Solar Absorbers as Revealed by Carrier‐Resolved Photo‐Hall Technique
摘要： With power conversion efficiencies now exceeding 25%, hybrid perovskite solar cells require deeper understanding of defects and processing to further approach the Shockley-Queisser limit. One approach for processing enhancement and defect reduction involves additive engineering—, e.g., addition of MASCN (MA = methylammonium) and excess PbI2 have been shown to modify film grain structure and improve performance. However, the underlying impact of these additives on transport and recombination properties remains to be fully elucidated. In this study, a newly developed carrier-resolved photo-Hall (CRPH) characterization technique is used that gives access to both majority and minority carrier properties within the same sample and over a wide range of illumination conditions. CRPH measurements on n-type MAPbI3 films reveal an order of magnitude increase in carrier recombination lifetime and electron density for 5% excess PbI2 added to the precursor solution, with little change noted in electron and hole mobility values. Grain size variation (120–2100 nm) and MASCN addition induce no significant change in carrier-related parameters considered, highlighting the benign nature of the grain boundaries and that excess PbI2 must predominantly passivate bulk defects rather than defects situated at grain boundaries. This study offers a unique picture of additive impact on MAPbI3 optoelectronic properties as elucidated by the new CRPH approach.
关键词： photo-Hall characterization,defect passivation,charge carrier transport,perovskites,charge recombination
更新于2025-09-12 10:27:22
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UV Resin Enhanced Stability of Metal Halide Perovskite Nanocrystals for White Light-Emitting Diodes
摘要： The long-term stability issue of metal halide perovskite nanocrystals (NCs) is one of the challenges for the applications in optoelectronic devices. Herein, we demonstrate the enhanced air, moisture, and light stability of these NCs by encapsulation into UV Resin (UVR). As prepared perovskite NCs-UVR composites exhibit well maintained optical properties. In addition, the composites show excellent stability with almost identical luminescent behavior for more than 60 days upon continuous exposure in air, moisture, light irradiation, which is superior to the other previous reports. Moreover, we have used these green- and red-emitting composite sheets to fabricate white light-emitting diodes (LEDs) by stacking them on top of the blue LED. We observed a bright neutral white light with a correlated color temperature of 5623 K, a color-rendering index of 85, and a high luminous efficacy of radiation (~349 lm/W). Our findings show the great potential of employing this technique for diverse photonic applications.
关键词： halide perovskites,UV resin,air and moisture stability,white light-emitting diodes,polymerization
更新于2025-09-12 10:27:22