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- 2018
- Inorganic perovskite quantum dots
- Stability
- Light-emitting diodes
- Optoelectronic Information Materials and Devices
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Spin-Controlled Charge Recombination Pathways across the Inorganic/Organic Interface
摘要： Charge transfer and recombination across the inorganic/organic interface in nanocrystal or quantum dot (QD)-molecule hybrid materials has been extensively studied. Principles of controlling charge transfer and recombination via energetics and electronic coupling have been established. However, the use of electron spin to control transfer and recombination pathways in such systems remains relatively underexplored. Here we use CdS QD-alizarin (AZ) as a model system to demonstrate this principle. Using time-resolved spectroscopy, we found that the charge separated states (QD--AZ+) created by selectively exciting AZ molecules mostly recombined to regenerate ground state complexes, whereas the apparently “same” charge separated states created by exciting QDs recombined to produce AZ molecular triplet states. Such a difference can be traced to the distinct spin configurations between excited QDs (QD*, with an ill-defined spin) and AZ (1AZ*, spin singlet) and the asymmetric electron and hole spin-flip rates in II-VI group QDs. The transferability of such a principle was confirmed by similar observations obtained for CdS QD-tetracene complexes. Opening an avenue of controlling charge transfer and recombination pathways via electron spin is potentially important for applications such as artificial photosynthesis.
关键词： CdS QD-alizarin,artificial photosynthesis,quantum dot,inorganic/organic interface,triplet states,electron spin,recombination,time-resolved spectroscopy,Charge transfer
更新于2025-09-23 15:19:57
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Enhanced photovoltaic performance and stability of perovskite solar cells by interface engineering with poly(4-vinylpyridine) and Cu2ZnSnS4&CNT
摘要： Organic-inorganic perovskite solar cells (PSCs) are emerging candidates for next generation photovoltaic devices. In the last decade, PSCs have depicted a rapid development in device performance, meanwhile, the issue of utilizing low-cost, non-toxic materials with chemical stability as well as long term device stabilities are still lacking. To address these issues, an inexpensive, eco-friendly, and environmentally stable nanostructure of the quaternary chalcogenide Cu2ZnSnS4 (CZTS) as an inorganic hole transport material (HTM) has been investigated. Moreover, simultaneously two strategies has been employed to optimize the photovoltaic parameters. First, an interlayer of poly(4-vinylpyridine) (PVP) has been applied between the perovskite and the hole transport layer (HTL). Second, single-walled carbon nanotubes (CNTs) is incorporated into the CZTS HTL. While, the latter only result in higher short circuit current density (Jsc) from 18.3 to 20 mA cm?2, by using both of the strategies an increase in open circuit voltage (Voc) from 0.98 to 1.05 V as well as Jsc from 18.3 to 20.5 mA cm?2 has been observed. The power conversion efficiency (PCE) of the record device reached to 15.2%, fill factor (FF) increased up to 70% and also demonstrated low hysteresis of 2.3%. The formation of hydrophobic CNT webs among the sphere-like CZTS nanostructures and the presence of the PVP polymeric interlayer results in highly stable devices, which retained more than 98% of the initial PCE at room temperature and 40–45% humidity after 30 days. Thus, our results show that the combination of PVP interlayer and CZTS&CNT HTL offer an opportunity for the scalability of PSCs.
关键词： Cu2ZnSnS4,Inorganic hole transport materials,Stability,Carbon nanotubes,Poly(4-vinylpyridine)
更新于2025-09-23 15:19:57
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Combustion-processed NiO/ALD TiO2 bilayer as a novel low-temperature electron transporting material for efficient all-inorganic CsPbIBr2 solar cell
摘要： Low-temperature ALD TiO2 electron transporting layers (ETLs) are promising for all-inorganic perovskite solar cells (PSCs), such as the CsPbIBr2-based ones. However, the non-ideal interfacial level-alignment between ALD TiO2 and CsPbIBr2, as well as the concomitant defects in ALD TiO2 during preparation of upper CsPbIBr2 film severely limit the performance of final PSC. We report herein a new design of ETL by combining ALD TiO2 with low-temperature combustion-processed NiO. Although the underlying NiO layer has a p-type conductivity and is known as a hole transporting layer (HTL), the NiO/ALD TiO2 bilayer can serve as an ETL with fewer traps, larger conduction band minimum (CBM) offset with CsPbIBr2 film, along with the similar optical transmittance, in contrast with individual ALD TiO2 ETL. Consequently, the resulting optimized CsPbIBr2 PSC yields the superior efficiency of 9.71% and photovoltage of 1.272 V, both of which exceed those of the one based on individual ALD TiO2 ETL and even so-gel TiO2 ETL. Our work verifies the great applicability of NiO/ALD TiO2 ETL for CsPbIBr2 PSC and thereby explores a promising way to develop more low-temperature ETLs by combining conventional HTLs with ALD TiO2 layers.
关键词： NiO/TiO2 bilayer,ALD,Low temperature,All-inorganic CsPbIBr2 solar cells,Solution combustion,Electron transporting material
更新于2025-09-23 15:19:57
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Vacuum-Controlled Growth of CsPbI <sub/>2</sub> Br for Highly Efficient and Stable All-Inorganic Perovskite Solar Cells
摘要： A high temperature annealing process (> 250°C) is always needed to obtain high-quality CsPbI2Br perovskite films, which makes it a challenge in the manufacture and application of flexible photovoltaic devices. In this work, a vacuum-controlled growth (VCG) that can effectively control the crystallization of perovskite and obtain high-quality films with larger grain size and low defect density at lower temperature is demonstrated. Besides a facile introduction of polyethyleneimine (PEIE) interlayer improves the charge extraction and suppresses carrier recombination. Therefore, the power conversion efficiency (PCE) of all-inorganic CsPbI2Br perovskite solar cell (PSC) reaches 12.32%. The unencapsulated PSCs with VCG treatment and PEIE modification show outstanding stabilities with retaining over 95% of initial PCE after being stored in N2 glove-box for over 1000h. This low temperature crystallization method and cheap transport material introduction drive the development for future commercialization of all inorganic perovskite solar cells.
关键词： vacuum controlled growth,interface modification,All inorganic perovskite solar cells,crystallization control,low temperature,film fabrication
更新于2025-09-23 15:19:57
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Cesium Lead Bromide Quantum Dot Light-Emitting Field-Effect Transistors
摘要： Solution processible perovskite quantum dots are considered as promising optical materials for light emitting optoelectronics. The light-emitting field-effect transistors that can be operated under relatively lower potential with an efficient energy conversion efficiency have yet to be realized with the perovskite quantum dot. Here, we present the CsPbBr3 quantum dot-based light-emitting field-effect transistor (LEFET). Surprisingly, unipolar transport characteristics with strong electroluminescence was observed at the interface of the CsPbBr3 QD-LEFET along with the exceptionally wide recombination zone of 80 μm, an order of magnitude larger than that of organic/polymer light-emitting field-effect transistors. Based on the systematic analysis for the electroluminescence of the CsPbBr3 NC-LEFET, we revealed that the increased diffusion length determined by the majority carrier mobility and the lifetime well explains the remarkably wide recombination zone. Furthermore, it was found that the energy-level matching and transport geometry of the hetero-structure also determine the charge distribution and recombination, substantially affecting the performance of the CsPbBr3 QD LEFET.
关键词： Organic/inorganic hybrid field-effect-transistor,Light emitting field-effect-transistor,Wide recombination zone,Diffusion length,CsPbBr3 quantum dots
更新于2025-09-23 15:19:57
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Thin silica-based microsheets with controlled geometry
摘要： A high demand for materials with defined geometry and size is required in a wide range of fields. Inorganic compounds, especially silica-based, arise as a cheap source and chemically flexible for the purpose. Silica display unique properties, like easy functionalization and good optical to manipulate. In this work, we developed a method to create thin silica microsheets with defined size and high-fidelity shape using superhydrophobic-hydrophilic microarrays. These microstructures were produced through sol-gel process using biomimetic superhydrophobic surfaces decorated with wettable spots. The results confirm the manufacture of porous silica microstructures with defined design (squares and circles) and thickness around 7 μm. The methodology applied in this work enables the high throughput fabrication of shaped silica materials in a single step, unlocking an extensive number of applications in areas that require miniaturization, like microelectronics or in fields like sensing and biomedicine.
关键词： Silica microsheets,High-fidelity shape,Inorganic materials,High throughput,Sol-gel process
更新于2025-09-23 15:19:57
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Self-driven all-inorganic perovskite microplatelet vertical Schottky junction photodetectors with a tunable spectral response
摘要： Wavelength-selective perovskite photodetectors (PDs) have many applications in optoelectronic field, such as machine vision, imaging and full-color display. However, the instability of organo-inorganic hybrid perovskite material severely limits the commercialization of perovskite-based PDs. In this work, a more stable all-inorganic perovskite, CsPbBr(3-x)Clx (x = 0, 1, 2, 3) microplatelets (MPs), were employed to fabricate Schottky PDs with a simple vertical structure of ITO/MP/Au. The optimized CsPbBr3 MP Schottky PDs exhibit rapid response speed (75 μs) and very low dark current (2 pA) at zero bias. Meanwhile, the device shows a high on/off ratio (>106), a large specific detectivity (>1012 Jones) and linear dynamic range (LDR = 137 dB) with excellent thermal and long-term stability. Furthermore, a tunable spectral response covering from the ultraviolet to visible range is also demonstrated. These results provide a simple avenue to realize self-driven and spectral tunable all-inorganic perovskite Schottky PDs with good stability.
关键词： all-inorganic perovskite,high temperature tolerance,tunable spectral response,vertical structure Schottky photodetector,weak-light sensitivity
更新于2025-09-23 15:19:57
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Effect of temperature on the performance of perovskite solar cells
摘要： The poor stability of perovskite solar cells is a crucial obstacle for its commercial applications. Here, we investigate the thermal stability of the mixed cation organic–inorganic lead halide perovskites (FAPbI3)1?xMAPb(Br3?yCly)x films and devices in air atmosphere. The results show that with the increase of heat treatment from 25 to 250 °C, the MA-perovskite decomposed into PbI2 firstly and the efficiency of corresponding solar cells reduced linearly. For the perovskite film, the increased heat treatment temperature can bring the redshift of the absorption edge leading to the decrease of band gap from 1.569 to 1.508 eV and increase of defect density from 3.87 × 1017 cm?3 to 9.03 × 1017 cm?3. However, a proper heat treatment time (10 min) at certain temperature (85 °C) can passivate defects effectively and improve the efficiency to 16.50%, realizing a 15% relative improvement of average efficiency. This work reveals a detailed thermal decomposition behavior of perovskite material and solar cells, which may provide insights into the stability of perovskite solar cells.
关键词： defect passivation,heat treatment,perovskite solar cells,thermal stability,mixed cation organic–inorganic lead halide perovskites
更新于2025-09-23 15:19:57
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Tailoring optoelectronic properties of CH3NH3PbI3 perovskite photovoltaics using al nanoparticle modified PC61BM layer
摘要： In photovoltaics, light harvesting is one of the critical factors for the enhancement of power conversion efficiency (PCE). Photon harvesting can be carried out by various methods in perovskite photovoltaic. The improved light harvesting can also be achieved by trapping the light by incorporating metallic nanoparticles at the interface or in the perovskite active layer itself. Either light is absorbed or scattered by metallic nanoparticles depending on the particle size. When light is absorbed by the nanoparticles (size < 20 nm), it behaves like a sub-wavelength antenna due to localized surface plasmon resonance (LSPR) excitation and hence near field effect of plasmonic particle will be interacting to CH3NH3PbI3 active layer. Larger particles (> 20 nm) act as sub-wavelength scattering centers of light and help in trapping incident light. In order to make use of dual effect poly-dispersed spherical aluminium nanoparticles (AlNPs) (size – 20–70 nm) were incorporated in the CH3NH3PbI3 perovskite solar cell at the PC61BM/Al electrode interface. As a result, there is an increase in the optical absorption in the AlNPs embedded device. A detailed study of optical absorption, absorbed light emission characteristics charge trap density and carrier concentration studies, photovoltaic property measurements indicates, improvement in power conversion efficiency arise due to enhancement in JSC. Evaluated device properties indicate that enhancement in JSC arises due to improvement in the active layer photon absorption by both scattering and plasmonic effect in addition to reduced series resistance.
关键词： Trap states,Organic-inorganic halide perovskite solar cell,Ultraviolet plasmonic resonance,Plasmonic nanoparticle current density,Metal nanoparticles
更新于2025-09-23 15:19:57
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Ambient-Processed, Additive-Assisted CsPbBr3 Perovskite Light-Emitting Diodes with Colloidal NiOx Nanoparticles for Efficient Hole Transporting
摘要： In this study, the electrically driven perovskite light-emitting diodes (PeLEDs) were investigated by hybridizing the organic polyethylene oxide, 1,3,5-tris (N-phenylbenzimiazole-2-yl) benzene (TPBi), and bis(3,5-di?uoro-2-(2-pyridyl)phenyl-(2-carboxypyridyl) iridium III (FIrpic) with CsPbBr3 in the emission layer and adopting the colloidal NiOx nanoparticle (NP) hole transport layer. The synthesized NiOx NPs, having an average size of ~5 nm, can be spin-coated to become a smooth and close-packed ?lm on the indium–tin–oxide anode. The NiOx NP layer possesses an overall transmittance of ~80% at 520 nm, which is about the peak position of electroluminescence (EL) spectra of CsPbBr3 emission layer. The coating procedures of NiOx NP and CsPbBr3 layers were carried out in ambient air. The novel PeLED turned on at 2.4 V and emitted bright EL of 4456 cd/m2 at 7 V, indicating the remarkable nonradiative-related defect elimination by organic additive addition and signi?cant charge balance achieved by the NiOx NP layer.
关键词： colloidal NiOx nanoparticles,organic additives,ambient-process,perovskite light-emitting diodes (PeLEDs),inorganic lead halide perovskites
更新于2025-09-23 15:19:57