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Lead Free, Aqua Stable A3Bi2I9 Perovskites: Crystal Growth and Blue Emitting Quantum dots [A = CH3NH3+, Cs+ and (Rb0.05Cs2.95)+]
摘要： Despite a great success in the rise in the power conversion efficiency of lead-halide perovskite solar cells, the toxicity of lead and the unstable nature of materials are the major concerns for their wide range of implementation at the industrial level. Herein, we have developed large size single crystals (SCs) in HI solution using temperature lowering method and nanocrystals (NCs) in ethanol (EtOH) and toluene (TOL) solvents of A3Bi2I9 perovskites [where, A = CH3NH3+ (MA)+, Cs+ and (Rb0.05Cs2.95)+]. The stability of A3Bi2I9 perovskite is investigated by immersing the SCs for 24 h and pellet for 12 h into water. Moreover, the A3Bi2I9 perovskite NCs displays a promising photoluminescence quantum yield of 17.63% and a longer lifetime of 8.20 ns.
关键词： Pb-Free Perovskites,Crystal Growth,High PLQY,Water Stability,Phase Transition,Nanocrystals,Low Bandgap
更新于2025-09-23 15:19:57
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Lighta??Emitting Nanophotonic Designs Enabled by Ultrafast Laser Processing of Halide Perovskites
摘要： Nanophotonics based on resonant nanostructures and metasurfaces made of halide perovskites have become a prospective direction for efficient light manipulation at the subwavelength scale in advanced photonic designs. One of the main challenges in this field is the lack of large-scale low-cost technique for subwavelength perovskite structures fabrication preserving highly efficient luminescence. Here, unique properties of halide perovskites addressed to their extremely low thermal conductivity (lower than that of silica glass) and high defect tolerance to apply projection femtosecond laser lithography for nanofabrication with precise spatial control in all three dimensions preserving the material luminescence efficiency are employed. Namely, with CH3NH3PbI3 perovskite highly ordered nanoholes and nanostripes of width as small as 250 nm, metasurfaces with periods less than 400 nm, and nanowire lasers as thin as 500 nm, corresponding to the state-of-the-art in multistage expensive lithographical methods are created. Remarkable performance of the developed approach allows to demonstrate a number of advanced optical applications, including morphology-controlled photoluminescence yield, structural coloring, optical-information encryption, and lasing.
关键词： metasurfaces,structural coloration,lasing,halide perovskites,light emission,nanostructures
更新于2025-09-23 15:19:57
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Aira??Stable Highly Crystalline Formamidinium Perovskite 1D Structures for Ultrasensitive Photodetectors
摘要： State-of-the-art optoelectronic devices based on metal-halide perovskites demand solution-processed structures with high crystallinity, controlled crystallographic orientation, and enhanced environmental stability. Formamidinium lead iodide (α-FAPbI3) possesses a suitable bandgap of 1.48 eV and enhanced thermal stability, whereas perovskite-type polymorph (α-phase) is thermodynamically instable at ambient temperatures. Stable α-FAPbI3 perovskite 1D structure arrays with high crystallinity and ordered crystallographic orientation are developed by controlled nucleation and growth in capillary bridges. By surface functionalization with phenylethylammonium ions (PEA+), FAPbI3 wires sustain a stable α-phase after 28 day storage in the ambient environment with a relative humidity of 50%. Enhanced photoluminescence (PL) intensity and elongated PL lifetime demonstrate suppressed trap density and high crystallinity in these 1D structures, which is also reflected by the enhanced diffraction density and pure (001) crystallographic orientation in the grazing-incidence wide-angle X-ray scattering (GIWAXS) pattern. Based on these high-quality 1D structures, sensitive photodetectors are achieved with average responsivities of 5282 A W?1, average specific detectivities of more than 1.45 × 1014 Jones, and a fast response speed with a 3 dB bandwidth of 15 kHz.
关键词： metal-halide perovskites,1D structures,photodetectors,α-FAPbI3
更新于2025-09-23 15:19:57
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A facile surface passivation method for efficient inorganic CsPbI2Br perovskite solar cells with efficiencies over 15%; é??????????oCsPbI2Bré??é??????¤aé?3è????μ?±?è?¨é?￠é????????????????1?3?;
摘要： Recently, perovskite solar cells (PVSCs) based on CsPbI2Br have attracted increasing attention owing to their good balance between efficiency and stability. Solution-processed CsPbI2Br perovskites usually contain various defects which need passivation for PVSCs with high-performance as well as good stability. Since the degradation of perovskite films usually begins at the grain boundaries, here we report a facile defect passivation strategy by spin-coating a KF solution on the CsPbI2Br perovskite surface. The deposited KF salt mostly locates at the grain boundaries of the perovskite surface, resulting in PVSCs with improved stability. Both steady-state and time-resolved photoluminescence results suggest that the defects of perovskite were significantly passivated by KF treatment. Consequently, the best-performance PVSC based on CsPbI2Br with KF treatment shows an enhanced power conversion efficiency (PCE) of 15.01% with a larger open circuit voltage (VOC) of 1.26 V in comparison with the pristine CsPbI2Br-based counterpart which exhibits an inferior PCE of 14.14% with a VOC of 1.18 V.
关键词： grain boundary,perovskites,defect,energy conversion,fluorides,passivation
更新于2025-09-23 15:19:57
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Ion Exchange/Insertion Reactions for Fabrication of Efficient Methylammonium Tin Iodide Perovskite Solar Cells
摘要： The low toxicity, narrow bandgaps, and high charge-carrier mobilities make tin perovskites the most promising light absorbers for low-cost perovskite solar cells (PSCs). However, the development of the Sn-based PSCs is seriously hampered by the critical issues of poor stability and low power conversion efficiency (PCE) due to the facile oxidation of Sn2+ to Sn4+ and poor film formability of the perovskite films. Herein, a synthetic strategy is developed for the fabrication of methylammonium tin iodide (MASnI3) film via ion exchange/insertion reactions between solid-state SnF2 and gaseous methylammonium iodide. In this way, the nucleation and crystallization of MASnI3 can be well controlled, and a highly uniform pinhole-free MASnI3 perovskite film is obtained. More importantly, the detrimental oxidation can be effectively suppressed in the resulting MASnI3 film due to the presence of a large amount of remaining SnF2. This high-quality perovskite film enables the realization of a PCE of 7.78%, which is among the highest values reported for the MASnI3-based solar cells. Moreover, the MASnI3 solar cells exhibit high reproducibility and good stability. This method provides new opportunities for the fabrication of low-cost and lead-free tin-based halide perovskite solar cells.
关键词： ion exchange/insertion reaction,solar cells,crystal growth,lead-free perovskites
更新于2025-09-23 15:19:57
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Interfacial engineering and film-forming mechanism of perovskite films revealed by synchrotron-based GIXRD at SSRF for high-performance solar cells
摘要： Organic-inorganic hybrid perovskites as promising light-harvesting materials have been the focus of scientific research and development of photovoltaics recently. Especially, metal halide perovskites currently become one of the most competitive candidates for the fabrication of solar cells with record certified efficiency over 25%. Despite the high efficiency, many fundamental questions remain unclear and need to be addressed at both the material and device levels, such as weaker stability, poorer reproducibility, easier degradation influenced by water, oxygen, thermal factors, and so on. Based on recent reports, interfacial engineering plays a crucial role in controlling the behavior of the charge carriers and in growing high quality, defect-free perovskite crystals, therefore helping to enhance device performance and operational stability. However, little attention has been paid to the interface interaction mechanism among carrier transport layers and perovskite active layer. It is extremely urgent to explore the perovskite interfaces in details and to find out how its interface structure is relative to the efficiency and hysteresis in perovskites solar cells. Based on the Shanghai Synchrotron Radiation Facility (SSRF), we have established an advanced perovskite photovoltaic device preparation and in-line test system, developed a series of unique surface diffraction analysis methods based on ex situ and in situ grazing incidence X-ray diffraction (GIXRD), and reported a large number of novel synchrotron radiation results on crystallization of the perovskite photovoltaics films. Our main investigations are aimed to deeply in-situ study the perovskite film growth dynamics using synchrotron radiation GIXRD technology in combination with a customized mini online glove box (c(H2O,O2)<1 ppm) and temperature-humidity control equipment, and so on., which should provide solid theoretical background and point to the useful direction for designing and fabricating high-performance perovskites solar cells. Moreover, a multi-functional joint characterization technology that in-situ GIXRD simultaneously combines with conventional characterization methods at synchrotron radiation beamline station must be put on the agenda in future research, which greatly promotes much more comprehensive and intuitive understanding of the nucleation, microcrystallization, and degradation mechanisms of perovskite heterojunction films, and therefore further optimizing their chemical synthesis strategies at the molecular level for functional materials.
关键词： Growth dynamics,Perovskites solar cells,Device performance,Grazing incidence X-ray diffraction,In-situ study
更新于2025-09-23 15:19:57
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Inkjet-Printed Organohalide 2D Layered Perovskites for High-Speed Photodetectors on Flexible Polyimide Substrates
摘要： The synthesis of solution-processed two-dimensional organohalide layered (CH3(CH2)3NH3)2(CH3NH3)n?1PbnI3n+1 (n = 2, 3, and 4) perovskites is presented, where inkjet printing was used to fabricate heterostructure flexible photodetector (PD) devices on polyimide (PI) substrates. Inks for the n = 4 formulation were developed to inkjet-print PD devices that were photoresponsive to broadband incoming radiation in the visible regime, where the peak photoresponsivity R was calculated to be ～0.17 A/W, which is higher compared to prior reports, while the detectivity D was measured to be ～3.7 × 1012 Jones at a low light intensity F ≈ 0.6 mW/cm2. The ON/OFF ratio was also high (～2.3 × 103), while the response time τ on the rising and falling edges was measured to be τ ≈ 24 ms and τ ≈ 65 ms, respectively. Our strain-dependent measurements, conducted here for the first time for inkjet-printed perovskite PDs, revealed that the Ip decreased by only ～27% with bending (radius of curvature of ～0.262 cm?1). This work demonstrates the tremendous potential of the inkjet-printed, composition-tunable, organohalide 2D perovskite heterostructures for high-performance PDs, where the techniques are readily translatable toward flexible solar cell platforms as well.
关键词： organohalide 2D perovskites,flexible photodetector,inkjet printing,photoluminescence spectroscopy,strain dependency
更新于2025-09-23 15:19:57
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with Optimal Band Gap for Photovoltaics and Defect-Insensitive Blue Emission
摘要： Despite rapid progress in the power-conversion efficiency of Pb-based perovskite solar cells, both the long-term instability and Pb toxicity are still the main challenges for their commercial applications. Here, by first-principles GW calculations, we find three kinds of two-dimensional (2D) 111-type Pb-free In-based halide perovskites of the form Cs3In2X9 (X = Cl, Br, I) as promising alternatives to the star material CH3NH3PbI3 (MAPbI3) because of the following excellent electronic, optical, and transport properties: (i) The 2D In-based halide perovskites are environmentally friendly lead-free materials. (ii) Compared with MAPbX3, they have greater structural stability. (iii) As energetic photovoltaic materials, 2D Cs3In2I9 perovskites are direct-band-gap semiconductors with optimal band gaps from 1.25 eV (trilayer) to 1.47 eV (monolayer). (iv) The 2D Cs3In2X9 perovskites have ideal band structures for solid-state lighting with a wide direct-optical-band-gap range (approximately 0.94–3.54 eV), covering the whole visible-light region, and light electron (heavy hole) effective mass, which will directly enhance the defect-insensitive emission efficiency due to the localization of holes. Particularly, Cs3In2BrxCl9?x has a suitable direct optical band gap for highly desired blue emission. (v) The absorption coefficient of Cs3In2X9 is up to 7 × 104 cm?1, which is between that of GaAs (104 cm?1) and that of MAPbI3 (105 cm?1). (vi) The estimated power-conversion efficiency in Cs3In2I9 reaches 28%, which is close to that of MAPbI3 (30%). These findings pave a way for designing nontoxic, stable, and high-performance photovoltaic and light-emitting devices.
关键词： light-emitting devices,photovoltaics,halide perovskites,lead-free,two-dimensional,first-principles calculations
更新于2025-09-23 15:19:57
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Reducing current fluctuation of Cs3Bi2Br9 perovskite photodetectors for diffuse reflection imaging with wide dynamic range
摘要： Recently, the newly booming metal halide perovskites have attracted extensive attention worldwide due to their outstanding optoelectronic performance, and are expected to be ideal candidates for photodetectors (PDs). However, there is still lack of perovskite PDs-based imaging devices coming into commercialization stage, due to some practical reasons including toxicity brought by lead-based perovskites and the large light current fluctuations. In this paper, for the first time we fabricate a lead-free Cs3Bi2Br9 perovskite PD, and build a prototype of this perovskite PD-based imaging system with diffuse reflection imaging mode. Moreover, we propose a new parameter F related to light current fluctuation to evaluate imaging performance of a PD especially for weak diffuse light condition, and prove its usability by comparison of unoptimized lead-free Cs3Bi2Br9 perovskite PD and atomic layer deposition (ALD) optimized Cs3Bi2Br9 PD. ALD-optimization can improve the quality of perovskite film and suppress the dark current and current fluctuation. Finally, we obtain satisfactory diffuse reflection images of 2D and 3D objects with wide dynamic range. Therefore, the ALD-optimized Cs3Bi2Br9 PD has addressed two major concerns about perovskite PDs-based imaging devices, that may extend application of perovskite materials and improve imaging quality.
关键词： Current fluctuations,Photodetectors,Diffuse reflection imaging,Cs3Bi2Br9 perovskites
更新于2025-09-23 15:19:57
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Molecular engineering of highly efficient dopant-free spiro-type hole transporting materials for perovskite solar cells
摘要： Up to now, the most efficient perovskite solar cells (PSCs) typically utilize Spiro-OMeTAD as hole transporting materials (HTMs). The unique “spiro” structure offers appropriate energy levels for hole transfer and high thermal stability with suppressed aggregation. However, the pristine Spiro-OMeTAD requires additional oxidizing dopants to work efficiently due to its low hole mobility. To retain the advantages of spiral structure and overcome its shortcomings, we demonstrate the design of three dopant-free HTMs with spiral structure by molecular engineering, in which three groups with different conjugated lengths, namely benzene, naphthalene and anthracene, are inserted between spiral core and electron donor. These designed molecules, Y-1~Y-3, are initially identified with quantum chemical calculations based on the mother molecule X59 and then are obtained by easy synthetic routes. Our studies show that the intramolecular charge transfer (ICT) states are formed in the designed molecules due to the introduction of conjugated groups, which produces a self-doping effect without the need to add any external dopant. The best-performing PSCs using the dopant-free Y-1 as HTM achieves a champion power conversion efficiency (PCE) of 16.29% under one sun illumination, which is higher than that of devices with X59 as dopant-free HTMs (14.64%). The present work provides an effective strategy for designing, synthesizing of highly efficient and stable dopant-free HTMs.
关键词： Perovskites solar cells,Dopant-free,Hole-transporting materials,Quantum chemical calculations,Spiral structure
更新于2025-09-23 15:19:57