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[IEEE 2018 IEEE 4th International Forum on Research and Technology for Society and Industry (RTSI) - Palermo, Italy (2018.9.10-2018.9.13)] 2018 IEEE 4th International Forum on Research and Technology for Society and Industry (RTSI) - Structural and Optical Behaviour of MAPbI<inf>3</inf> Layers in Nitrogen and Humid Air
摘要： The tendency of MA+-containing perovskites to degradation under humid air is still the main challenge which limits the durability of technologies. We indeed frame the behavior of MAPbI3 layer through structural and optical characterization under thermal cycles and using the environmental composition as a variable parameter (humid air, N2, Ar, O2). Within the temperature range explored (RT-80°C) we likely approach the thermal operation of the material under the sun and find that the degradation mechanism is linked to the action of water molecules by the formation of lattice defects. They rise the lattice disorder, especially at the crossover of the tetragonal to cubic transition wherein an acceleration of the degradation kinetics is observed. Nitrogen can help rationalizing solutions to stabilize the materials even at this critical transition step, since it behaves as more than an inert species.
关键词： Spectroscopic Ellipsometry,Photovoltaics,X-ray diffraction,Hybrid Perovskites,Stability,Thermal Cycle
更新于2025-09-23 15:22:29
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Setup to Study the in Situ Evolution of Both Photoluminescence and Absorption during the Processing of Organic or Hybrid Semiconductors
摘要： In situ measurement techniques, applied during the solution processing of novel semiconductors such as organic semiconductors or hybrid perovskites, have become more and more important to understand their film formation. In that context, it is crucial to determine how the optical properties, namely photoluminescence (PL) and absorption, evolve during processing. However, until now PL and absorption have mostly been investigated independently, significantly reducing the potential insights into film formation dynamics. To tackle this issue we present the development of a detection system that allows simultaneous measurement of full absorption and PL spectra during solution processing of the investigated film. We also present a spin-coater system attachable to the detection system, where the temperature of the substrate on which the film is processed can be changed. We performed test measurements by spin coating the well-known conjugated polymer P3HT demonstrating the potential of this technique. By considering absorption and corresponding PL, we extract the PL quantum yield (PLQY) during processing, which decreases with substrate temperature. Furthermore, we identify a significant red shift of the PL just prior to the onset of the aggregation process, indicating the importance of chain planarization prior to solid film formation.
关键词： photoluminescence,in situ measurement,organic semiconductors,hybrid perovskites,spin-coating,film formation,absorption,P3HT
更新于2025-09-23 15:21:21
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Methylammonium Polyiodides in Perovskite Photovoltaics: From Fundamentals to Applications
摘要： Discovered in 2017, methylammonium polyiodides were proposed as a facile precursor for synthesis of hybrid perovskites by means of their interaction with metallic lead, which initiated further active exploration of their potential applications. Investigation of their unusual properties such as liquid state, unprecedented phase diversity and high reactivity revealed that methylammonium polyiodides are the first representatives of a new class of compounds—reactive polyhalide melts (RPM). In this review, we summarize the reported data on the unique properties of these compounds, discuss their potential for fabrication of hybrid perovskite films and describe the role of polyhalides in degradation of perovskite solar cells.
关键词： perovskites,methylammonium polyiodides,hybrid perovskites,perovskite solar cells,RPM,reactive polyiodide melts
更新于2025-09-23 15:21:01
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Transparent, flexible MAPbI3 perovskite microwire array passivated with ultra-hydrophobic supramolecular assembly for stable and high-performance photodetectors
摘要： The emergence of organic-inorganic hybrid perovskites (OHPs) has revolutionised the potential performance of optoelectronic devices, most perovskites are opaque and hence incompatible with transparent optoelectronics, and sensitive to environmental degradation. Here, a single-step fabrication of ultra-long MAPbI3 perovskite microwire array over a large-area using stencil lithography based on a sequential vacuum sublimation. The environmental stability of MAPbI3 is empowered a newly designed and synthesized transparent supramolecular self-assembly, based on a mixture of two tripodal L-Phe-C11H23/C7F15 molecules, which showed a contact angle of 105° and served as ultra-hydrophobic passivation layer for more than 45 days in ambient atmosphere. The MAPbI3 microwire array passivated with supramolecular self-assembly demonstrate for the first time both excellent transparency of ~89% at 550 nm and remarkable photoresponse with photo-switching ratio of ~104, responsivity of 789 A/W, detectivity of 1014 Jones, linear dynamic range of ~ 122 dB, and rise time of 432 μs. Furthermore, the photodetector fabricated on flexible PET substrate demonstrated robust mechanical flexibility even beyond 1200 bending cycles. Therefore, the scalable stencil lithography and supramolecular passivation approaches have the potential to deliver next-generation transparent, flexible, and stable optoelectronics.
关键词： transparency,stencil lithography,photodetectors,MAPbI3,supramolecular self-assembly,flexibility,organic-inorganic hybrid perovskites,environmental stability
更新于2025-09-23 15:21:01
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General Synthesis Principles for Ruddlesden-Popper Hybrid Perovskite Halides from a Dynamic Equilibrium
摘要： Two-dimensional (2D) Ruddlesden-Popper hybrid perovskites are a homologous series of compounds with the formula A’2An–1BnX3n+1 (A’ = bulky organic cation; A = small organic cation; B = Pb2+ or Sn2+, X = Cl–, Br–, I–; n is an integer) composed of inorganic octahedra layers separated by organic spacer cations. The octahedral layer thickness is modified by the stoichiometry of the A site cation, but limited methods exist for controlled and discriminating synthesis for all compositions. We report a general synthesis method and its principles that yield phase-pure 2D hybrid perovskites; the chemistry operates within a dynamic equilibrium established by the molar solubility of the compounds within the homologous series. A solvent-antisolvent (HI-acetic acid) pair and the common-ion effect provide selective control over the molar solubility to precipitate phase-pure compounds, as is supported by simple and predictive calculations. Here, this approach is demonstrated in detail with A’ = n-butylammonium, A = methylammonium, and n ≤ 3 and is applied to the synthesis and discovery of materials with other bulky ammonium cations (e.g., iso-butylammonium and benzylammonium).
关键词： dynamic equilibrium,Ruddlesden-Popper,molar solubility,common-ion effect,hybrid perovskites,solvent-antisolvent,synthesis
更新于2025-09-23 15:21:01
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Promoting Photocatalytic H <sub/>2</sub> Evolution on Organic–Inorganic Hybrid Perovskite Nanocrystals by Simultaneous Dual-Charge Transportation Modulation
摘要： Organic-inorganic hybrid perovskites have demonstrated great potential in solar cells fabrication due to the excellent optoelectronic properties. However, their success in solar cells has been hardly translated to producing solar fuels due to the instability issue and serious charge recombination at the nanoscale domain. Herein, we show for the first time that organic-inorganic hybrid perovskite methylammonium lead bromide (MAPbBr3) nanocrystals can be stabilized in aqueous HBr solution and achieve photocatalytic H2 production reaction under visible light. More impressively, by hybridizing MAPbBr3 with Pt/Ta2O5 and poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) nanoparticles as electron and hole transporting motifs, respectively, drastically enhanced charge transportation on MAPbBr3 together with improved catalysis were achieved. As a consequence, the rate of photocatalytic hydrogen evolution on pristine MAPbBr3 was increased by ca. 52 times by introducing dual nanoscale charge transporting highways, achieving an apparent quantum efficiency of ca. 16.4% for H2 evolution at 420 nm.
关键词： Organic-inorganic hybrid perovskites,photocatalytic H2 evolution,visible light,charge transportation,MAPbBr3 nanocrystals
更新于2025-09-23 15:21:01
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Thina??Film Morphology Improvement and Density Functional Theorya??Driven Findings for the Photovoltaic Perovskite MAPI/MAPSI
摘要： The morphology of thin films of the mixed MAPI / MAPSI material has been studied, revealing that the addition of toluene in the synthesis stage markedly improves the porosity problem of the manufactured films. The presence of crystalline domains of the two materials is verified, as reported by the X-ray diffraction patterns. The calculated band gap values from the diffuse reflectance measurements using the Tauc plots with the Kubelka-Munk transformation function confirm the presence of the two materials in the mixture. On the other hand, the results of the DFT-based computational calculations give answers to the true geometry that the SCN groups adopt within the MAPSI unit cell. The COHP analysis suggests that the most stable structure has an axial geometry for the SCN groups, which is confirmed by the analysis of non-covalent interactions (NCI), in which it is established that there is a greater number of hydrogen bond interactions for the same axial configuration, and results for Electron Localization Functions were shown (ELF), where it is found that there is indeed electron localization (at the level at which a bonding interaction is expected, ELF > 0.8) both for the SCN groups and the methyl-ammonium cations, in the same way as seen in the results of the NCI analyses.
关键词： hybrid perovskites,solar cells,thin films,SEM,DFT calculations
更新于2025-09-23 15:19:57
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High-Performance UVa??Vis Photodetectors Based on a Lead-Free Hybrid Perovskite Crystal (MV)[SbI <sub/>3</sub> Cl <sub/>2</sub> ]
摘要： Low-dimensional lead-free organic?inorganic hybrid perovskites have gained increasing attention as having low toxicity, ease of processing, and good optoelectronic properties. Seeking for lead-free and narrow band gap organic?inorganic hybrid perovskites are of great importance for the development and application of photoelectric materials. Here, we reported a Sb-based organic?inorganic hybrid perovskite (MV)[SbI3Cl2], which has one-dimensional inorganic frameworks of the I-sharing double octahedra. (MV)[SbI3Cl2] shows a narrow direct band gap of 1.5 eV, and displays obvious photoresponse for the 532 nm light with rapid response speed of trise = 0.69 s, tdecay = 0.28 s. With an illumination power of 5 mW and a 50 V bias, the responsivities (R) and external quantum e?ciency (EQE) for (MV)[SbI3Cl2] photodetector under 532 nm laser are 29.75 mA/W and 6.69% respectively. This Sb-based halide double perovskite material will provide an alternative material for photodetector devices.
关键词： organic?inorganic hybrid perovskites,Sb-based,narrow band gap,photodetectors,lead-free
更新于2025-09-23 15:19:57
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Investigation of Dimethylammonium Solubility in MAPbBr <sub/>3</sub> Hybrid Perovskite: Synthesis, Crystal Structure, and Optical Properties
摘要： The possible existence of mixed methylammonium (MA)/dimethylammonium (DMA) lead bromide hybrid perovskites of general formula MA1?xDMAxPbBr3 (0 ≤ x ≤ 1) was investigated. A combined X-ray di?raction and solid-state nuclear magnetic resonance approach indicates that DMA can be incorporated up to about x = 0.30 while retaining the cubic lattice of MAPbBr3. By increasing the DMA content (x), the absorption shows a progressive blue shift and the band gap moves from about 2.17 eV (x = 0) to about 2.23 (x = 0.30) with a concomitant slightly faster recombination in the mixed cation powders.
关键词： X-ray diffraction,hybrid perovskites,optical properties,mixed methylammonium,solid-state nuclear magnetic resonance,lead bromide,dimethylammonium
更新于2025-09-23 15:19:57
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Tailoring properties of hybrid perovskites by domain-width engineering with charged walls
摘要： Charged ferroelectric domain walls are fascinating electrical topological defects that can exhibit unusual properties. Here, in the search for novel phenomena, we perform and analyze first-principles calculations to investigate the effect of domain width on properties of domains with charged walls in the photovoltaic material consisting of methylammonium lead iodide hybrid perovskite. We report that such domains are stable and have rather low domain wall energy for any investigated width (that is, up to 13 lattice constants). Increasing the domain width first linearly decreases the electronic band gap from ?1.4 eV to about zero (which therefore provides an efficient band-gap engineering), before the system undergoes an insulator-to-metal transition and then remains metallic (with both the tail-to-tail and head-to-head domain walls being conductive) for the largest widths. All these results can be understood in terms of: (i) components of polarization along the normal of the domain walls being small in magnitude; (ii) an internal electric field that is basically independent of the domain width; and (iii) rather negligible charge transfer between walls. These findings deepen the knowledge of charged ferroelectric domain walls and can further broaden their potential for applications, particularly in the context of halide perovskites for photovoltaics.
关键词： charged ferroelectric domain walls,hybrid perovskites,photovoltaic materials,band-gap engineering,insulator-to-metal transition
更新于2025-09-23 15:19:57