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Impact of Organic Spacers on the Carrier Dynamics in 2D Hybrid Lead-Halide Perovskites
摘要： We have carried out non-adiabatic molecular dynamics simulations combined with time-dependent density functional theory calculations to compare the properties of the two-dimensional (2D) (BA)2(MA)Pb2I7 and three-dimensional (3D) MAPbI3 (where MA = methylammonium and BA = butylammonium) materials. We evaluate the different impacts that the 2D-confined spacer layer of butylammonium cations and the 3D-confined methylammonium cations have on the charge carrier dynamics in the two systems. Our results indicate that while both the MA+ and BA+ cations play important roles in determining the carrier dynamics, the BA+ cations exhibit stronger non-adiabatic couplings with the 2D perovskite framework. The consequence is a faster hot-carrier decay rate in 2D (BA)2(MA)Pb2I7 than in 3D MAPbI3. Thus, tuning of the functional groups of the organic spacer cations in order to reduce the vibronic couplings between the cations and the Pb-I framework can offer the opportunity to slow down the hot-carrier relaxations and increase the carrier lifetimes in 2D lead-halide perovskites.
关键词： carrier dynamics,2D hybrid lead-halide perovskites,time-dependent density functional theory,non-adiabatic molecular dynamics,organic spacers
更新于2025-09-23 15:21:21
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A Review: Crystal Growth for High-Performance All-inorganic Perovskite Solar Cells
摘要： Recently, halide perovskites have become one of the most promising materials for solar cells owing to their outstanding photoelectric performance. Among them, metal halide all-inorganic perovskites (CsPbX3; where X denotes a halogen) show superior thermal and light stability. In particular, the power conversion efficiency (PCE) of perovskite solar cells (pero-SCs) based on a CsPbX3 active layer has shown a steady increase from 2.7% to 19.03% with the improvement of the CsPbX3 crystal quality. In this review, we summarize methodologies that have been employed for controlling the growth of all-inorganic perovskite films so far, including precursor solution deposition, substrate modification, composition doping, and surface engineering. Furthermore, we discuss the effect of perovskite crystal characteristics on defects and perovskite film morphology, both of which are closely related to device performance. Finally, conclusions and perspectives are presented along with useful guidelines for developing all-inorganic pero-SCs with high PCE and robust stability.
关键词： light stability,halide perovskites,precursor solution deposition,all-inorganic perovskites,surface engineering,substrate modification,thermal stability,power conversion efficiency,CsPbX3,composition doping,solar cells,crystal growth
更新于2025-09-23 15:21:01
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Effect of Grain Size on the Fracture Behavior of Organic-Inorganic Halide Perovskite Thin Films for Solar Cells
摘要： Organic-inorganic halide perovskite (OIHP) thin ?lms at the heart of the new perovskite solar cells (PSCs) are very brittle, limiting the mechanical reliability of PSCs. Here we show that ?ne-grained MAPbI 3 (prototypical OIHP) ?lms with grain size (~290 nm) smaller than the typical ?lm thickness (~500 nm) tend to fracture intergranularly, resulting in low toughness (0.41 J.m ?2 ). In contrast, MAPbI 3 /substrate interfacial fracture occurs in ?lms with grains larger (~730 nm) than the ?lm thickness, resulting in much higher toughness (1.14 J.m ?2 ). Thus, coarse-grained OIHP ?lms are deemed desirable for not only improved PSCs performance and stability but also mechanical reliability.
关键词： Thin ?lms,Solar cells,Halide perovskites,Mechanical behavior,Grain boundaries
更新于2025-09-23 15:21:01
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Thermally Stable, Efficient, Vapor Deposited Inorganic Perovskite Solar Cells
摘要： We report on thermally stable inorganic mixed halide perovskite solar cells deposited using a vapor deposition technique with no loss in device performance at 200 °C for 72 hours. X-ray diffraction analysis confirms no compositional degradation of the perovskite layer up to 200 °C anneals. We use a layer-by-layer vapor deposition technique with thin layers (several nm) of PbI2 and CsBr precursors to fabricate inorganic mixed halide perovskite solar cells with a photoconversion efficiency of 11.8%. We study the effect of several key parameters of the perovskite fabrication process that control the intermixing of the perovskite layer and their effect on device efficiency and hysteresis. The thermal stability of the perovskite material and its energy band gap of 1.87eV makes it appropriate for use in tandem junction cells for use in real-life environments with high solar illuminance where the ambient temperatures exceed 55 °C in the summer, and silicon cell module temperatures approach 86 °C.
关键词： Thermal Stability,inorganic perovskite solar cells,vacuum deposition,mixed halide perovskites,layer-by-layer deposition,thermal degradation
更新于2025-09-23 15:21:01
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Oriented Crystallization of Mixeda??Cation Tin Halides for Highly Efficient and Stable Leada??Free Perovskite Solar Cells
摘要： As the most promising lead-free branch, tin halide perovskites suffer from the severe oxidation from Sn2+ to Sn4+, which results in the unsatisfactory conversion efficiency far from what they deserve. In this work, by facile incorporation of methylammonium bromide in composition engineering, formamidinium and methylammonium mixed cations tin halide perovskite films with ultra-highly oriented crystallization are synthesized with the preferential facet of (001), and that oxidation is suppressed with obviously declined trap density. MA+ ions are responsible for that impressive orientation while Br- ions account for their bandgap modulation. Depending on high quality of the optimal MA0.25FA0.75SnI2.75Br0.25 perovskite films, their device conversion efficiency surges to 9.31% in contrast to 5.02% of the control formamidinium tin triiodide perovskite (FASnI3) device, along with almost eliminated hysteresis. That also results in the outstanding device stability, maintaining above 80% of the initial efficiency after 300 h of light soaking while the control FASnI3 device fails within 120 h. This paper definitely paves a facile and effective way to develop high-efficiency tin halide perovskites solar cells, optoelectronic devices, and beyond.
关键词： trap density,methylammonium bromide,oriented crystallization,tin halide perovskites,divalent tin ions
更新于2025-09-23 15:21:01
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Robust Wavelength-Converting and Lasing Media from Wafer-Scale Inorganic Perovskites Enabled by a Protective Surface Layer
摘要： Despite that the inorganic halide perovskites show great promise in wavelength-conversion and lasing applications, the stability and scalability remain as the obstruction toward practical applications. Herein, we, for the first time, employ the wafer-scale inorganic perovskite single crystals to address the above issue. Our spectroscopic analysis reveals that the carrier trapping on the crystal surface is the most probable culprit to hinder the optical amplification for the weak-penetrating one-photon pumping, whilst, the interior of the crystal preserves intact and show low-threshold stimulated emission by two-photon absorption in the near infrared regime. Thanks to the effective protection from the surface layer, the stimulated emission maintains 90% of the initial intensity upon uninterrupted pumping of 4 hours and shows nearly constant threshold upon long-term storage without any encapsulation (> one year). By exploiting a parallel-mirror cavity, an optically pumped wavelength-converting and laser device featuring a spatially coherent output beam is constructed. Our finding greatly advances the development of practical coherent light sources based on halide perovskites.
关键词： wavelength-conversion,lasing,scalability,two-photon absorption,inorganic halide perovskites,stability,coherent light sources,stimulated emission
更新于2025-09-23 15:21:01
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Tin halide perovskite films made of highly oriented 2D crystals enable more efficient and stable lead-free perovskite solar cells
摘要： Low toxicity and an ideal energy bandgap make 2D Ruddlesden-Popper tin-based halide perovskites a promising photovoltaic material. However, the disordered crystal orientation and the oxidation of Sn2+ to Sn4+ still need to be addressed. Here, we demonstrate that the annealing of FASnI3 assisted by phenyl ethyl ammonium chloride enables the formation of more ordered 2D tin-based perovskite crystals oriented vertically. We use in-situ synchrotron-based grazing incident X-ray diffraction (GIXRD) to correlate the higher crystal orientation to the better device performance. We measured a maximum power conversion efficiency of >9%. Furthermore, we demonstrate that the phenyl ethyl ammonium chloride acts as a barrier layer at the surface of the crystals protecting the tin from the oxidation. Hence, this work paves the way for more efficient and stable lead-free perovskite solar cells.
关键词： phenyl ethyl ammonium chloride,photovoltaic material,crystal orientation,lead-free perovskite solar cells,oxidation of Sn2+,2D Ruddlesden-Popper tin-based halide perovskites,power conversion efficiency
更新于2025-09-23 15:21:01
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Mechanisms of LiF Interlayer Enhancements of Perovskite Light-Emitting Diodes
摘要： The use of LiF as a thin interlayer between the electron transport layer and cathode has played a pivotal role in remarkable advances in perovskite LEDs (PeLEDs); however, the mechanism behind the effect of LiF remains to be fully understood. Here we report a combined experimental and computational study from which we ascribe the benefits of a LiF interlayer to the migration of dissociated Li into the cathode and dissociated F into the anode. Electronic device simulations reveal that the former improves electron injection by lowering the Schottky barrier height, while the latter reduces the barrier width. These reduce turn-on voltage and improve current density and charge balance in LEDs. We fabricate PeLEDs with and without the LiF interlayer and link these materials and electronic phenomena to the device light-current-voltage characteristics. X-ray photoelectron spectroscopy obtained in sputter profiling of PeLEDs corroborates the dissociation of LiF.
关键词： LEDs,interface dipoles,metal-halide perovskites,photoelectron spectroscopy,band alignment
更新于2025-09-23 15:21:01
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Photoluminescencea??Based Characterization of Halide Perovskites for Photovoltaics
摘要： Photoluminescence spectroscopy is a widely applied characterization technique for semiconductor materials in general and halide perovskite solar cell materials in particular. It can give direct information on the recombination kinetics and processes as well as the internal electrochemical potential of free charge carriers in single semiconductor layers, layer stacks with transport layers, and complete solar cells. The correct evaluation and interpretation of photoluminescence requires the consideration of proper excitation conditions, calibration and application of the appropriate approximations to the rather complex theory, which includes radiative recombination, non-radiative recombination, interface recombination, charge transfer, and photon recycling. In this article, an overview is given of the theory and application to specific halide perovskite compositions, illustrating the variables that should be considered when applying photoluminescence analysis in these materials.
关键词： halide perovskites,photoluminescence,photovoltaics,charge carriers,recombination kinetics
更新于2025-09-23 15:21:01
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Dual-site mixed layer-structured FA <sub/>x</sub> Cs <sub/>3a??x</sub> Sb <sub/>2</sub> I <sub/>6</sub> Cl <sub/>3</sub> Pb-free metal halide perovskite solar cells
摘要： Structure engineering of trivalent metal halide perovskites (MHPs) such as A3Sb2X9 (A ? a monovalent cation such as methyl ammonium (MA), cesium (Cs), and formamidinium (FA) and X ? a halogen such as I, Br, and Cl) is of great interest because a two dimensional (2D) layer structure with direct bandgap has narrower bandgap energy than a zero dimensional (0D) dimer structure with indirect bandgap. Here, we demonstrated 2D layer structured FACs2Sb2I6Cl3 MHP by dual-site (A and X site) mixing. Thanks to the lattice-symmetry change by I–Cl mixed halide, the shortest ionic radius of Cs, and the lower solution energy due to dual-site mixing, the FACs2Sb2I6Cl3 MHP had 2D layer structure and thereby the MHP solar cells exhibited improved short-circuit current density.
关键词： metal halide perovskites,2D layer structure,bandgap engineering,dual-site mixing,solar cells
更新于2025-09-23 15:21:01