- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Defects anomaly in cobalt-doped ZnO nanostructures using optical and charge transient analysis
摘要： The significant effect of electrically active defects present in the device, which limits the carrier mobility, generated due to cobalt doping via the co-precipitation technique in a ZnO matrix, has been investigated on the basis of its structural, optical and charge transient behaviours. The variations observed in the absorbance and extinction coefficients as a function of wave length reveal the presence of defect states, a range of localized states and structural disorder. The presence of a non-uniform trap centre density in the material has been measured on the basis of different operational modes in charge-deep level transient spectroscopic analysis. A disparity of such a kind in the structures at the nanoscale will provide for a remarkable approach to improve the performance and reliability of the smart electronic, optoelectronics, photonics and sensing devices.
关键词： absorption coefficient,ZnO,Defect density,Q-DLTS,Nano structures,extinction coefficient
更新于2025-09-23 15:22:29
-
High Phase Stability in CsPbI <sub/>3</sub> Enabled by Pba??I Octahedra Anchors for Efficient Inorganic Perovskite Photovoltaics
摘要： CsPbI3 inorganic perovskite has exhibited some special properties particularly crystal structure distortion and quantum confinement effect, yet the poor phase stability of CsPbI3 severely hinders its applications. Herein, the nature of the photoactive CsPbI3 phase transition from the perspective of PbI6 octahedra is revealed. A facile method is also developed to stabilize the photoactive phase and to reduce the defect density of CsPbI3. CsPbI3 is decorated with multifunctional 4-aminobenzoic acid (ABA), and steric neostigmine bromide (NGBr) is subsequently used to further mediate the thin films’ surface (NGBr-CsPbI3(ABA)). The ABA or NG cation adsorbed onto the grain boundaries/surface of CsPbI3 anchors the PbI6 octahedra via increasing the energy barriers of octahedral rotation, which maintains the continuous array of corner-sharing PbI6 octahedra and kinetically stabilizes the photoactive phase CsPbI3. Moreover, the added ABA and NGBr not only interact with shallow- or deep-level defects in CsPbI3 to significantly reduce defect density, but also lead to improved energy-level alignment at the interfaces between the CsPbI3 and the charge transport layers. Finally, the champion NGBr-CsPbI3(ABA)-based inorganic perovskite solar cell delivers 18.27% efficiency with excellent stability. Overall, this work demonstrates a promising concept to achieve highly phase-stabilized inorganic perovskite with suppressed defect density for promoting its optoelectronic applications.
关键词： inorganic perovskite,phase stability,PbI6 octahedra anchors,CsPbI3,defect density
更新于2025-09-23 15:21:01
-
Simulation and optimization of CH3NH3SnI3 based inverted perovskite solar cell with NiO as Hole transport material
摘要： A planar perovskite solar cell (PSC) with p-i-n inverted structure is modeled and simulated using SCAPS software to determine the power output characteristics under illumination. The inverted structure is NiO/CH3NH3SnI3/PCBM where NiO is the hole transport layer (HTL), CH3NH3SnI3 is the perovskite absorber layer and PCBM is the electron transport layer (ETL). Simulation efforts are focused on thickness of three layers, defect density of interfaces, density of states, and metal work function effect on power conversion ef?ciency (PCE) of solar cell. For optimum parameters of all three layers, ef?ciency of 22.95% has been achieved. From the simulations, an alternate lead free inverted perovskite solar cell is introduced.
关键词： Electron transport material,Transparent conducting oxide,Inverted perovskite solar cell,Hole transport material,Device simulation,Defect density
更新于2025-09-23 15:19:57
-
Binary synergetic ions reduce defect density in ambient air processed perovskite solar cells
摘要： At present, significant research efforts are being concentrated on enhancing the performance and stability of perovskite solar cells (PSC) by lowering defect traps. In this study, NH4+ and SCN- binary ions as additive were incorporated into perovskite precursor to control the crystal growth. Our best performance based on the devices fabricated under fully open air condition was improved from 15.67 to 18.75%, boosting by 20%. The stability results display that devices containing additive maintained ~90% of the initial efficiency for 400 h in ambient air with a humidity of 30%. We first study the fundamentals of defect properties and carrier recombination kinetics behind the multifaceted role of mixed NH4+ and SCN- ions. Compared to using a single active specie as additive, mixed-ions devices exhibit effective bifacial trap passivation as well as lowered defect density in not only perovskite bulk material but also interfaces significantly, leading to facilitated electron transport. Our work can manifest a simple ambient air based approach by the mixed binary ions as additives in order to potentially promote the commercial prospects of PSCs.
关键词： Ambient air process,Performance and stability,Defect density,Binary synergetic ions,Perovskite solar cell
更新于2025-09-23 15:19:57
-
Efficient Nanorod Arrays Perovskite Solar Cells: A Suitable Structure for High Strontium-Substitution in a Nature Environment
摘要： Organic-inorganic hybrid perovskite solar cells (PSCs) have become a research hotspot because of their excellent power conversion efficiency (PCE), but the presence of toxic lead (Pb) in perovskite film has significantly limited their commercial application. In this study, using a TiO2 nanorod arrays (TNRAs) as the electron transport layer (ETL), strontium chloride (SrCl2) was chosen to fabricate lead-less PSCs in air environment (relative humidity, RH=50%) by a simple two-step spin-coating method. The influence of introduced strontium (Sr) on the perovskite films and cell properties was systematically investigated by various characterization methods. With increasing Sr substitution amount from 0 to 15 mol%, the formed perovskite films with a compact structure and a large crystalline size essentially remained invariable, while residual PbI2 was reduced, which is beneficial for the cell performance. The optimal PCE of 16.08% (average PCE = 15.37%) was obtained for the 5 mol% Sr-substituted PSCs because of the enhanced charge extraction from the perovskite film to the TNRAs and the suppressed charge recombination in the PSC. Both the humidity and thermal stability of the Sr-substituted PSCs were improved. More importantly, the 15 mol% Sr-substituted PSCs still exhibited a PCE of 15.09% in air (RH = 50%), maintaining 99% of the cell efficiency of the pristine (0 mol% Sr) PSC (15.27%), suggesting that the TNRAs structure is suitable for synthesis of high Sr-substituted lead-less PSCs.
关键词： Lead-less perovskite solar cells,TiO2 nanorod arrays,Defect density,Strontium substitution,Recombination
更新于2025-09-19 17:13:59
-
Efficient and Stable Inverted Perovskite Solar Cells Incorporating Secondary Amines
摘要： Large-bandgap perovskites offer a route to improve the efficiency of energy capture in photovoltaics when employed in the front cell of perovskite–silicon tandems. Implementing perovskites as the front cell requires an inverted (p–i–n) architecture; this architecture is particularly effective at harnessing high-energy photons and is compatible with ionic-dopant-free transport layers. Here, a power conversion efficiency of 21.6% is reported, the highest among inverted perovskite solar cells (PSCs). Only by introducing a secondary amine into the perovskite structure to form MA1?xDMAxPbI3 (MA is methylamine and DMA is dimethylamine) are defect density and carrier recombination suppressed to enable record performance. It is also found that the controlled inclusion of DMA increases the hydrophobicity and stability of films in ambient operating conditions: encapsulated devices maintain over 80% of their efficiency following 800 h of operation at the maximum power point, 30 times longer than reported in the best prior inverted PSCs. The unencapsulated devices show record operational stability in ambient air among PSCs.
关键词： defect density,perovskite solar cells,inverted structure,secondary amine,stability
更新于2025-09-19 17:13:59
-
Defect Density-Dependent Electron Injection From Excited-State Ru(II) Tris-Diimine Complexes Into Defect- Controlled Oxide Semiconductors
摘要： Dye-sensitized solar cells and photocatalysts that consist of a light absorbing dye and a wide gap oxide semiconductor substrate have been studied extensively as a means of solar energy conversion. Although defects existing at an oxide surface have a significant impact on the electron injection efficiency from the excited state dye-molecule into the oxide, the effects of defects on the electron injection process has not been fully understood in any dye-sensitized system. In this study, we present a systematic evaluation of electron injection into defects using emissive Ru(II) complexes adsorbed on oxide substrates (HCa2Nb3O10 nanosheets and nonstoichiometric SrTiO3—"), which had different defect densities. Using these oxides, electron injection from adsorbed Ru(II) complexes was observed by time-resolved emission spectroscopy. It was shown that electron injection from the excited state Ru(II) complex into an oxide was influenced by the defect density of the oxide as well as by the excited state oxidation potential (Eox*) of the Ru(II) complex. Electron injection was clearly accelerated with increasing defect density of the oxide, and was inhibited with increasing electron density of the oxide because of a trap-filling effect. Even though the Eox* of the Ru(II) complex was more positive than the conduction band edge potential of the oxide, electron injection into defects could be identified when a defective oxide was employed. The electron injection event is discussed in detail, on the basis of the defect density and the energy levels of oxides as well as the Eox* values of Ru(II) complexes. Overall the results suggest that it is possible to estimate the potential of surface defect states in an oxide by changing Eox* of an emissive complex dye.
关键词： Dye-sensitized solar cells,defect density,electron injection,Ru(II) complexes,time-resolved emission spectroscopy,photocatalysts
更新于2025-09-11 14:15:04
-
Two-level system damping in a quasi-one-dimensional optomechanical resonator
摘要： Nanomechanical resonators have demonstrated great potential for use as versatile tools in a number of emerging quantum technologies. For such applications, the performance of these systems is restricted by the decoherence of their fragile quantum states, necessitating a thorough understanding of their dissipative coupling to the surrounding environment. In bulk amorphous solids, these dissipation channels are dominated at low temperatures by parasitic coupling to intrinsic two-level system (TLS) defects; however, there remains a disconnect between theory and experiment on how this damping manifests in dimensionally reduced nanomechanical resonators. Here, we present an optomechanically mediated thermal ringdown technique, which we use to perform simultaneous measurements of the dissipation in four mechanical modes of a cryogenically cooled silicon nanoresonator, with resonant frequencies ranging from 3–19 MHz. Analyzing the device’s mechanical damping rate at fridge temperatures between 10 mK and 10 K, we demonstrate quantitative agreement with the standard tunneling model for TLS ensembles con?ned to one dimension. From these ?ts, we extract the defect density of states (P0 ～ 1?4 × 1044 J?1 m?3) and deformation potentials (γ ～ 1–2 eV), showing that each mechanical mode couples on average to less than a single thermally active defect at 10 mK.
关键词： Quantum technologies,Nanomechanical resonators,Optomechanical,Mechanical damping rate,Deformation potentials,Tunneling model,Defect density of states,Two-level system (TLS) defects,Silicon nanoresonator
更新于2025-09-09 09:28:46