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- 2018
- Inorganic perovskite quantum dots
- Stability
- Light-emitting diodes
- Optoelectronic Information Materials and Devices
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Insights into mechanism of size-controlled synthesis of CH3NH3PbBr3 perovskite quantum dots and large nanoparticles with tunable optical properties
摘要： There is a common phenomenon in the preparation of perovskite quantum dots (QDs) by reprecipitation method that large particles were always produced with desired QDs. Understanding the fabrication mechanism can contribute to improve this phenomenon. Herein, we demonstrate a two-step strategy for synthesis of perovskite QDs and large nanoparticles (LNPs), where the growth of QDs and LNPs involves two possible pathways, the quick intercalation reaction process and the dissolution-recrystallization process. Following two pathways, we have created QDs with high photoluminescence quantum yields (ca. 46–71%), tunable size (ca. 3.2–5.4 nm) and LNPs with tunable size from 25 to 300 nm, where their emission wavelength can be tuned from 500 nm to 534 nm. Importantly, based on the comprehensive insight into the formation mechanism, we have achieved the conversion from LNPs to QDs partly through adding surfactants properly, which is expected to pave the way for the development of pure production of perovskite QDs.
关键词： Surfactant ligands,Quantum dots,Optical properties,Hybrid organic-inorganic perovskite,Size-controlled
更新于2025-09-23 15:21:01
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Growth control and defect passivation toward efficient and low-temperature processed carbon based CsPbIBr2 solar cell
摘要： All-inorganic perovskite CsPbIBr2, has drawn much attention for photovoltaic (PV) application due to its excellent intrinsic stability. However, low device performance and high fabrication temperature still hamper its further progress in flexible application. Herein, Zn substitution has been used to improve the nucleation and growth process for low temperature processed a-phase CsPbIBr2 film. Zn incorporated CsPbIBr2 film exhibits good crystallinity, compact surface morphology and depressed defect state. Low temperature (100 and 160°C) processed carbon based CsPbIBr2 solar cells with improved PV performance have been prepared by using Zn incorporation and room deposited electron transport layer (ETL). A champion efficiency over 9% can be achieved through Zn substitution, which is one of the best values reported for the low temperature processed CsPbIBr2 solar cell without using hole transport layer (HTL). Efficiency over 5% can also be achieved for larger area (1 cm2) rigid and flexible CsPbIBr2 solar cells. These results would provide a new route for preparing high-performance and low temperature processed inorganic perovskite solar cell.
关键词： Carbon electrode,CsPbIBr2,Flexible,Solar cell,Low temperature,Inorganic perovskite
更新于2025-09-23 15:21:01
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Estimation of the Rashba Strength from Second Harmonic Generation in 2D and 3D Hybrid Organic-Inorganic Perovskites
摘要： The Rashba e?ect (RE), caused by concurrent spin-orbit coupling and structural inversion asymmetry (SIA), has been invoked to explain outstanding optoelectronic properties of hybrid organic inorganic perovskites (HOIPs). The SIA in HOIPs also manifests itself in second harmonic generation (SHG). Here we establish a quantitative relation between the RE strength and the low-frequency SHG value in 2D and 3D HOIPs using a newly developed e?ective-mass model. The calculated SHG, which exhibits one- and two-photon resonances between the valence and conduction bands, approaches a ?nite value at low frequencies. Using the measured SHG values in literature, the estimated RE strength is 10?3 eV?A for 3D CH3NH3PbI3 and 4 × 10?2 eV?A for 2D (C4H9NH3)2PbI4. Our results facilitate a simple and reliable determination of the RE strength of 2D and 3D HOIPs and help quantify the impact of RE on various properties in HOIPs.
关键词： second harmonic generation,Rashba effect,hybrid organic-inorganic perovskites,structural inversion asymmetry,spin-orbit coupling
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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Ethanol–water-assisted room temperature synthesis of CsPbBr3/SiO2 nanocomposites with high stability in ethanol
摘要： All-inorganic halide perovskites have attracted great attention by virtue of the merits of bright emission, tunable wavelength and narrow-band emission. Despite the excellent optical features, all-inorganic halide perovskite materials have suffered from intrinsic instability, which has limited their applications in various optoelectronic devices. To mitigate the intractable issue, we demonstrated the CsPbBr3 nanoparticles decorated with smaller SiO2 nanocrystals to passivate the surface defects; SiO2 nanoparticles were applied as a barrier layer to maintain the optical property and enhance environmental stability. A facile in situ method was proposed to prepare CsPbBr3/SiO2 nanocomposites, in which an environmental ethanol/water solvent system was needed with the addition of tetraethyl orthosilicate (TEOS) as a silicon precursor. The obtained CsPbBr3/SiO2 nanocomposites have better optical characteristic and stability than bare CsPbBr3 nanoparticles. Even 70% photoluminescence intensity of as-prepared CsPbBr3/SiO2 nanocomposites can be maintained after 168 h storage in ethanol. This newly developed synthesis will open up a new route for the fabrication of optoelectronic devices in an environmentally friendly way, and the as-obtained perovskite materials with improved stability will make them great potential for multifunctional optoelectronic devices.
关键词： Ethanol–water-assisted room temperature synthesis,All-inorganic halide perovskites,High stability,CsPbBr3/SiO2 nanocomposites,Optoelectronic devices
更新于2025-09-23 15:21:01
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Kinetics of Ion-Exchange Reactions in Hybrid Organic-Inorganic Perovskite Thin Films Studied by In Situ Real-Time X-ray Scattering
摘要： The exchange of ions in hybrid organic-inorganic perovskites with the general formula APbX3 (A = MA, FA; X = I, Cl, Br) is studied in five different systems using in situ real-time grazing incident X-ray diffraction (GIXD). In systems where the organic cation is exchanged, we find a continuous shift of the lattice parameter. The relative shift compared to the pure materials is used to quantify the exchange. Whether or not a conversion is possible, as well as the amount of exchanged cations, depends on the halide used. In the case of the interconversion of MAPbI3 and MAPbCl3, we observe a decay of the diffraction peaks of the original perovskite and the emergence of new peaks corresponding to the structure with the alternative halide. Moreover, we determined the relevant time scales of the growth and decay of the perovskite structures.
关键词： ion-exchange reactions,kinetics,in situ real-time X-ray scattering,thin films,hybrid organic-inorganic perovskites
更新于2025-09-23 15:21:01
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Higha??Efficiency CsPbI <sub/>2</sub> Br Perovskite Solar Cells with Dopanta??Free Poly(3a??hexylthiophene) Hole Transporting Layers
摘要： CsPbI2Br is emerging as a promising all-inorganic material for perovskite solar cells (PSCs) due to its more stable lattice structure and moisture resistance compared to CsPbI3, although its device performance is still much behind this counterpart. Herein, a preannealing process is developed and systematically investigated to achieve high-quality CsPbI2Br films by regulating the nucleation and crystallization of perovskite. The preannealing temperature and time are specifically optimized for a dopant-free poly(3-hexylthiophene) (P3HT)-based device to target dopant-induced drastic performance degradation for spiro-OMeTAD-based devices. The resulting P3HT-based device exhibits comparable power conversion efficiency (PCE) to spiro-OMeTAD-based devices but much enhanced ambient stability with over 95% PCE after 1300 h. A diphenylamine derivative is introduced as a buffer layer to improve the energy-level mismatch between CsPbI2Br and P3HT. A record-high PCE of 15.50% for dopant-free P3HT-based CsPbI2Br PSCs is achieved by alleviating the open-circuit voltage loss with the buffer layer. These results demonstrate that the preannealing processing together with a suitable buffer layer are applicable strategies for developing dopant-free P3HT PSCs with high efficiency and stability.
关键词： perovskite solar cells,inorganic perovskites,P3HT
更新于2025-09-23 15:19:57
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Prospects of Coupled Organica??Inorganic Nanostructures for Charge and Energy Transfer Applications
摘要： We review the field of organic-inorganic nanocomposites with a focus on materials that exhibit a significant degree of electronic coupling across the hybrid interface. These nanocomposites undergo a variety of charge and energy transfer processes, enabling optoelectronic applications in devices which exploit singlet fission, triplet energy harvesting, photon upconversion or hot charge carrier transfer. We discuss the physical chemistry of the most common organic and inorganic components. Based on those we derive synthesis and assembly strategies and design criteria on material and device level with a focus on photovoltaics, spin memories or optical upconverters. We conclude that future research in the field should be directed towards an improved understanding of the binding motif and molecular orientation at the hybrid interface.
关键词： Inorganic Nanostructures,Self-Assembly,Organic π-Systems,Optoelectronic Devices,Plasmonics
更新于2025-09-23 15:19:57
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Aa??Site Rubidium Cationa??Incorporated CsPbI <sub/>2</sub> Br Alla??Inorganic Perovskite Solar Cells Exceeding 17% Efficiency
摘要： Due to its excellent thermal stability and high performance, the inorganic cesium lead mixed-halide (ABX3, where A=Cs, B=Pb and X= I/Br)all inorganic perovskite solar cells (IPVSCs) attracted much interest in the optoelectronic applications. However, the film quality, enough absorption by desired film thickness and nature of partial replacement of cations determine the stability of the CsPbI2Br perovskite films. Here, we employed a hot air method to control the thickness and morphology of the CsPbI2Br perovskite thin film and the A-site (herein, Cs+) cation is partially incorporated by rubidium (Rb+) cation for making stable black-phase in ambient condition. The Rb-cation incorporated Cs1-xRbxPbI2Br (x=0 to 0.03) perovskite thin films exhibited high crystallinity, uniform grains, extremely dense and pinhole free morphology. The fabricated device having Cs0.99Rb0.01PbI2Br perovskite composition with poly(3-hexylthiophene-2,5-diyl) (P3HT) as a hole transporting layer (HTL) exhibited 17.16 % power conversion efficiency (PCE), which is much higher than the CsPbI2Br based IPVSCs. The fabricated Cs0.99Rb0.01PbI2Br based IPVSC devices retain > 90 % of the initial efficiency over 120 hours at 65 °C thermal stress, which is much higher than CsPbI2Br sample.
关键词： all inorganic perovskite solar cells,hot air,A-site rubidium cation incorporation
更新于2025-09-23 15:19:57
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The influence of electrode for electroluminescence devices based on all-inorganic halide perovskite CsPbBr<sub>3</sub>
摘要： Electroluminescence devices based all-inorganic halide perovskite material with the excellent luminescence performance have been studied extensively in recent years. However, the important role for the electrodes of electroluminescence devices is payed few attention by theoretical and experimental studies. Appropriate electrodes can reduce the Schottky barrier height to decrease the energy loss, and prevent the metal impurities from diffusing into the perovskite material to generate deep traps levels, which improves the luminous efficiency and lifetime of devices. In this paper, not only the interface effects between CsPbBr3 and common metal electrode (Ag, Au, Ni, Cu and Pt) are studied by first-principle calculations, but also the diffusion effects of metal electrode atom into the CsPbBr3 layer are also explored by nudged elastic band calculations. The calculated results show the metal Ag is more suitable for the cathode for CsPbBr3 electroluminescence devices, while the metal Pt is more applicable for the anode. Based on the overall consideration about the interface effects and diffusion effects of the CsPbBr3-metal electrode junctions, the essential principle provide a valuable reference how to select the suitable electrodes for other electroluminescence devices.
关键词： electroluminescence devices,diffusion effects,Schottky barrier height,CsPbBr3,all-inorganic halide perovskite,metal electrodes
更新于2025-09-23 15:19:57