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Copper sulfide nanoparticles as hole-transporting-material in a fully-inorganic blocking layers n-i-p perovskite solar cells: Application and working insights
摘要： One of the challenges in the field of perovskite solar cells (PSC) is the development of inorganic hole-transporting-materials (HTM) suitable for solution-processed deposition, in order to have cheaper, more stable and scalable devices. Herein, we report the synthesis and characterization of p-type copper sulfide nanoparticles for their application for the first time as a low-cost, fully-inorganic HTM in mesoscopic n-i-p PSC. By employing CuS combined with two different perovskites, CH3NH3PbI3 (MAPbI3) and (FAPbI3)0.78(MAPbBr3)0.14(CsPbI3)0.08 (CsFAMAPbIBr), very high current densities and fill-factors are observed, suggesting an effective hole-extraction happening at the CuS interface. Noticeable, our cells exhibit one of the highest power conversion efficiencies (PCE) in n-i-p configuration employing a sole solution-processed inorganic HTM via non-toxic solvents, leading to 13.47% and 11.85% for MAPbI3 and CsFAMAPbIBr, respectively. As a remark, such PCE values are only limited by a reduced open-circuit voltage around 0.8 V, due to different phenomena occurring at perovkite/CuS interface such as an increased non-radiative recombination, caused by considerable difference in valence band value, and the effect of CuS metallic character. Overall, these findings highlight CuS as an extremely cheap alternative to common organic HTMs and pave the way to new improvements employing this material in full-inorganic blocking layers PSC.
关键词： perovskite solar cells.,Copper sulfide,interfaces,inorganic hole-transporting-material
更新于2025-10-22 19:40:53
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Hole Blocking Layer-Free Perovskite Solar Cells with High Efficiencies and Stabilities by Integrating Subwavelength-Sized Plasmonic Alloy Nanoparticles
摘要： Perovskite solar cells hold great promise as prospective alternatives of renewable power sources. Recently hole blocking layer-free perovskite solar cells, getting rid of complex and high-temperature fabrication processes, have engaged in innovative designs of photovoltaic devices. However, the elimination of the hole blocking layer constrains the energy conversion efficiencies of perovskite solar cells, and severely degrades the stabilities. In this paper a simple approach (without energy-consuming and time-consuming procedures) for the fabrication of hole blocking layer-free perovskite solar cells has been demonstrated by an integration of copper-silver alloy nanoparticles, which are synthesized by wet chemical method with controllable diameters and elemental compositions. The rear-side integration of the subwavelength-sized silver-copper alloy particles (200 nm diameter), through a spraying/drying method, realizes a pronounced absorption enhancement of the perovskite layer by effectively light scattering in a broadband wavelength range, and achieves a series resistance decrease of the solar cell due to high electrical conductivities of the alloy particles. The particle integration achieves the highest efficiency of 18.89% due to the significant improvement in both optical and electrical properties of solar cells, making this device one of the highest-performing blocking layer-free perovskite solar cells and plasmonic perovskite solar cells. Moreover, the copper-based nanoparticles prevent the perovskite from diffusing into metal back electrodes. Because the diffusion can lead to a severe corrosion of the Au electrode and thus an efficiency degradation, the alloy nanoparticle integration between the perovskite and the electrode results in 80% and 200% improvements in the long-term stability and the photostability of solar cells, respectively. Through the proposed simple and effective fabrication process, our results open up new opportunities in the manufacturability of perovskite solar cells.
关键词： light scattering,Perovskite solar cells,plasmonic,subwavelength-sized,alloy,hole blocking layer,stability
更新于2025-10-22 19:40:53
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Fabrication of highly efficient and stable hole‐transport material free perovskite solar cells through morphology and interface engineering: full ambient process
摘要： Carbon based hole-transport material (HTM) free perovskite solar cells (PVSCs) with low cost and high stability have attracted research interests. Here, we report a facile way to improve the performance of HTM free PVSCs by employing two strategies: firstly, adding a small amount of tetrahydrofuran (THF) in lead iodide (PbI2)/N,N-dimethylformamide (DMF) solution to improve the quality of perovskite film; secondly, introducing an ultra-thin Al2O3 film at the interface of TiO2/perovskite to reduce charge recombination. THF is found to facilitate the formation of homogenous perovskite films with better coverage, while the ultra-thin Al2O3 layer will avoid the direct contact of TiO2 with CH3NH3PbI3. The Al2O3 layer can effectively block holes and prevents charge recombination, thus lead to a dramatic improvement of open circuit voltage and fill factor in PVSCs. Moreover, our PVSCs show excellent long term stability with no degradation for 1000 hours under ambient conditions. We provide a facile way for the future commercialization of efficient low-cost HTM-free PVSCs.
关键词： hole conductor free,interface engineering,perovskite solar cells,high stability
更新于2025-10-22 19:40:53
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Tin( <scp>ii</scp> ) thiocyanate Sn(NCS) <sub/>2</sub> – a wide band gap coordination polymer semiconductor with a 2D structure
摘要： Semiconductors based on tin(II) show promising hole-transport characteristics due to the 5s electrons that form the valence band. In this paper, we report the synthesis and comprehensive characterization of tin(II) thiocyanate [Sn(NCS)2] and identify it as a novel transparent coordination polymer semiconductor. The single crystal X-ray analysis reveals covalently-bonded 1D polymeric chains that form a 2D structure through Sn–S tetrel bonds. Density functional theory calculations also confirm the importance of the van der Waals interactions between the 2D sheets. Furthermore, we show that the s character of Sn(II) is maintained at the top of the valence band, resulting in dispersed states with a small hole effective mass. The coordination with NCS ligands also leads to a conduction band which is high in energy, giving rise to a wide band gap and excellent transparency in the visible spectrum. This is the first report on the electronic properties of Sn(NCS)2 which highlights the potential of developing new transparent semiconductors based on thiocyanate coordination polymers.
关键词： hole transport,band gap,tin(II) thiocyanate,transparent,semiconductor,coordination polymer
更新于2025-10-22 19:40:53
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Projector-based renormalization approach to electron-hole-photon systems in their nonequilibrium steady state
摘要： We present an extended version of the projector-based renormalization method that can be used to address not only equilibrium but also nonequilibrium situations in coupled fermion-boson systems. The theory is applied to interacting electrons, holes, and photons in a semiconductor microcavity, where the loss of cavity photons into vacuum is of particular importance. The method incorporates correlation and fluctuation processes beyond mean-field theory in a wide parameter range of detuning, Coulomb interaction, light-matter coupling, and damping, even in the case when the number of quasiparticle excitations is large. This enables the description of exciton and polariton formation and their possible condensation through spontaneous phase symmetry breaking by analyzing the ground-state, steady-state, and spectral properties of a rather generic electron-hole-photon Hamiltonian, which also includes the coupling to two fermionic baths and a free-space photon reservoir. Thereby, the steady-state behavior of the system is obtained by evaluating expectation values in the long-time limit by means of the Mori-Zwanzig projection technique. Tracking and tracing different order parameters, the fully renormalized single-particle spectra and the steady-state luminescence, we demonstrate the Bose-Einstein condensation of excitons and polaritons and its smooth transition when the excitation density is increased.
关键词： exciton condensation,nonequilibrium steady state,semiconductor microcavity,projector-based renormalization method,electron-hole-photon systems,Bose-Einstein condensation,polariton condensation
更新于2025-09-23 15:23:52
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Combined effects of unsteady wake and free-stream turbulence on turbine blade film cooling with laid-back fan-shaped holes using PSP technique
摘要： Detailed film cooling effectiveness distribution for a gas turbine blade under the effects of unsteady wakes and oncoming free-stream turbulence intensities was obtained using pressure sensitive paint (PSP) technique. Tests were performed on a linear cascade at Reynolds number of 3.85 × 10^5 based on the blade chord at cascade exit. Upstream unsteady wakes were simulated using a spoke-wheel type wake generator. The test blade has three rows of compound angled cylindrical film holes at the leading edge, five rows of laid-back fan-shaped holes on the pressure surface and three rows of laid-back fan-shaped holes on the suction surface. The wake Strouhal number was varied from 0 to 0.36 and three mass flux ratios were determined. The oncoming free-stream turbulence intensities are 2.7% and 26.9%, respectively. Results show that the effect of the mass flux ratio on the film cooling effectiveness decreases under the high turbulence intensity and unsteady wake conditions. In most regions of the blade surface, the film cooling effectiveness decreases with the increase of wake Strouhal number, and the free-stream turbulence superimposed on the unsteady wake reduces the film cooling effectiveness further. The effect of the unsteady wake decreases under the high free-stream turbulence conditions.
关键词： Turbulence intensity,Film cooling effectiveness,PSP,Wake,Mass flux ratio,Turbine blade,Strouhal number,Laid-back fan-shaped hole
更新于2025-09-23 15:23:52
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Bound states in the continuum in the double-period rectangular hole arrays perforated in one layer of photonic crystal slab in the visible wavelength region
摘要： We investigate optical bound states in the continuum (BICs) supported by a photonic crystal (PhC) slab penetrated with two periodic rectangular hole arrays embedded each other parallelly and vertically. It proves that the tunable off-Γ BICs can be found in the structure of both types, but the at-Γ BICs can only be obtained in the parallel structure. Quality factors (Q-factor) are obtained extremely high exceeding 105 for both types of structures. The tunable off-Γ BICs can be modulated by the structure parameters. Especially, the sensitivity of the resonant wavelength on the surrounding medium refractive index change is very large for the structure in both types, and tunable off-Γ BICs can be tuned by varying the environmental index. The results above accord well from the finite difference time domain method (FDTD) and the temporal coupled mode theory (CMT), which are beneficial to design practical resonance elements based on optical BICs in various new optical applications.
关键词： Double-periodic rectangular hole arrays,Photonic crystal,Fano resonance,Bound state in the continuum
更新于2025-09-23 15:23:52
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Evidence and Influence of Copper Vacancies in p-Type CuGaO <sub/>2</sub> Mesoporous Films
摘要： Delafossite CuGaO2 nanocrystals were hydrothermally synthesized and characterized spectroscopically and electrochemically as mesoporous thin films. The nanocrystals demonstrate a preferred orientation within the film structure, as shown by enhancement of the (00l) peaks via two-dimensional powder X-ray diffraction. Annealing conditions of low and high temperature (i.e., 100?300 °C), with oxygen and/or argon atmospheres, were investigated, and the resulting effect on the thin film electrochemistry was measured. Cyclic voltammetry showed an increase in non-faradaic current with higher annealing temperatures and demonstrated a quasi-reversible redox feature (E1/2 = 0.1 V vs Fc+1/0). This feature is assigned to a CuII/CuI redox couple associated with surface defects. X-ray photoelectron and energy dispersive spectroscopies provide evidence for CuII surface defects and copper vacancies. Electrochemical impedance spectroscopy revealed that CuGaO2 films were highly conductive with σ ～ 10?5 Ω?1 cm?1, consistent with a large density of hole carriers induced by copper vacancies. The significance of synthesis, film preparation, and annealing conditions on the presence of surface defects and large hole densities is discussed. The prevalence of such defects in delafossite CuGaO2 is expected to have a large impact on the use of this material as a hole transport layer in solar cell architectures.
关键词： p-type metal oxide,delafossite,hole transport,heterojunction solar cell,CuGaO2
更新于2025-09-23 15:23:52
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Full waveform inversion based on inequality constraint for cross-hole radar
摘要： Cross-hole radar is an effective method for geophysical exploration of underground geological conditions. Besides cross-hole radar, some geological information can be obtained by other methods, such as preliminary geological survey, geologic drilling and long-distance geophysical prospecting. This information can work as priori information to help interpret cross-hole radar detection data. Full waveform inversion (FWI) is an advanced inversion method for cross-hole radar, having higher resolution than the ray tomography method. However, traditional FWI for cross-hole radar takes less advantage of the prior information. Therefore, the introduction of the priori information into FWI is worthy of in-depth study to improve information and improve the accuracy and stability of FWI. The reasonable value inversion quality. Here we use a special penalty function to impose inequality constraint on the objective function, and then calculate a new update step length value different from the traditional FWI. We use this method to introduce the priori range of weight coefficients is discussed, which can control the strength of inequality constraint. Several inversion examples are designed to validate the effect of this improved FWI method. The inversion examples for synthetic and field data show that FWI based on inequality constraint for cross-hole radar has better inversion effect than the traditional FWI. To a certain extent, the introduction of inequality constraint can constrain inversion process, improve the inversion stability and provide higher precision inversion results.
关键词： Inequality constraint,Inverse theory,Cross-hole radar,Full waveform inversion,Priori information
更新于2025-09-23 15:23:52
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-doped two-dimensional semiconductor quantum wells
摘要： We present a theoretical study of photoabsorption in n-doped two-dimensional (2D) and quasi-2D semiconductors that takes into account the interaction of the photocreated exciton with Fermi-sea (FS) electrons through (i) Pauli blocking, (ii) Coulomb screening, and (iii) excitation of FS electron-hole pairs—that we here restrict to one. The system we tackle is thus made of one exciton plus zero or one FS electron-hole pair. At low doping, the system ground state is predominantly made of a 'trion-hole'—a trion (two opposite-spin electrons plus a valence hole) weakly bound to a FS hole—with a small exciton component. As the trion is poorly coupled to photon, the intensity of the lowest absorption peak is weak; it increases with doping, thanks to the growing exciton component, due to a larger coupling between two-particle and four-particle states. Under a further doping increase, the trion-hole complex is less bound because of Pauli blocking by FS electrons, and its energy increases. The lower peak then becomes predominantly due to an exciton dressed by FS electron-hole pairs, that is, an exciton-polaron. As a result, the absorption spectra of n-doped semiconductor quantum wells show two prominent peaks, the nature of the lowest peak turning from trion-hole to exciton-polaron under a doping increase. Our work also nails down the physical mechanism behind the increase with doping of the energy separation between the trion-hole peak and the exciton-polaron peak, even before the anticrossing, as experimentally observed.
关键词： Fermi sea,trion-hole complex,exciton-polaron,photoabsorption,Pauli blocking,n-doped semiconductors,Coulomb screening
更新于2025-09-23 15:23:52