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The silicon heterojunction (SHJ) solar cell has long been considered as one of the most promising candidates for the next-generation PV market. Transition metal oxides (TMOs) show good carrier selectivity when combined with c-Si solar cells. This has led to the rapid demonstration of the remarkable potential of TMOs (especially MoO x ) with high work function to replace the p-type a-Si:H emitting layer. MoO x can induce a strong inversion layer on the interface of n-type c-Si, which is beneficial to the extraction and conduction of holes. In this paper, the radio-frequency (RF) magnetron sputtering is used to deposit MoO x films. The optical, electrical and structural properties of MoO x films are measured and analyzed, with focus on the inherent compositions and work function. Then the MoO x films are applied into SHJ solar cells. When the MoO x works as a buffer layer between ITO/p-a-Si:H interface in the reference SHJ solar cell, a conversion efficiency of 19.1% can be obtained. When the MoO x is used as a hole transport layer (HTL), the device indicates a desirable conversion efficiency of 17.5%. To the best of our knowledge, this current efficiency is the highest one for the MoO x film as HTL by RF sputtering.

The pulsations and translations of cavitation bubbles obey combined ordinary differential equations, and their nonlinearities are studied by the bifurcation diagram and the phase diagram in a strong ultrasonic field. Bubble pulsation can change regularly or irregularly with changing driving pressure in the time domain. The bifurcation diagrams of the pulsation versus driving pressure show that the pulsations and translations of bubbles have nonlinear characteristics, and the nonlinear translations of bubbles can disorder the pulsations for certain parameters. Disorder of the pulsation can also be caused by nonlinear pulsation itself. In addition, the phase diagrams also show that the nonlinear translations make a large contribution to the pulsations. The same result can also be obtained when the ambient radii of two bubbles are different.

Stone–Wales (SW) defects are possibly formed in graphene and other two-dimensional materials, and have multiple influence on their physical and chemical properties. In this study, the transition state of SW defects in graphene is determined with the fully discrete Peierls theory. Furthermore, the atomic formation process is investigated by means of ab-initio simulations. The atomic structure change and energetics of the SW transformation are revealed. It is found that the transition state is at the SW bond rotation of 34.5° and the activation energy barrier is about 12 eV. This work provides a new method to investigate SW transformations in graphene-like materials and to explore unknown SW-type defects in other 2D materials.

Coper thiocyanate (CuSCN) is generally considered as a very hopeful inorganic hole transport material (HTM) in semitransparent perovskite solar cells (ST-PSCs) because of its low parasitic absorption, high inherent stability, and low cost. However, the poor electrical conductivity and low work function of CuSCN lead to the insufficient hole extraction and large open-circuit voltage loss. Here, 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4TCNQ) is employed to improve conductivity of CuSCN and band alignment at the CuSCN/perovskite (PVK) interface. As a result, the average power conversion efficiency (PCE) of PSCs is boosted by ≈ 11%. In addition, benefiting from the superior transparency of p-type CuSCN HTMs, the prepared bifacial semitransparent n–i–p planar PSCs demonstrate a maximum efficiency of 14.8% and 12.5% by the illumination from the front side and back side, respectively. We believe that this developed CuSCN-based ST-PSCs will promote practical applications in building integrated photovoltaics and tandem solar cells.

Hydrogenated amorphous silicon oxide (a-SiO x :H) is an attractive passivation material to suppress epitaxial growth and reduce the parasitic absorption loss in silicon heterojunction (SHJ) solar cells. In this paper, a-SiO x :H layers on different orientated c-Si substrates are fabricated. An optimal effective lifetime (τ eff) of 4743 μs and corresponding implied open-circuit voltage (i V oc) of 724 mV are obtained on 〈100〉-orientated c-Si wafers. While τ eff of 2429 μs and i V oc of 699 mV are achieved on 〈111〉-orientated substrate. The FTIR and XPS results indicate that the a-SiO x :H network consists of SiO x (Si-rich), Si– OH, Si– O– SiH x , SiO2≡Si– Si, and O3 ≡S– Si. A passivation evolution mechanism is proposed to explain the different passivation results on different c-Si wafers. By modulating the a-SiO x :H layer, the planar silicon heterojunction solar cell can achieve an efficiency of 18.15%.

The pulsation and translation of two cavitation bubbles are studied numerically in sound field. The results show that bubbles’ pulsation driven by the sound makes them translate. Different pulsations lead to different translations. Two bubbles will be mutually attractive to each other if they pulsate in phase, while they will be repulsive if out of phase. Furthermore, the secondary Bjerknes force for small phase difference is attractive, and it becomes repulsive for other phase differences up to π phase difference due to the nonlinear effect, although the attractive strength between two bubbles is much larger than the repulsive strength. Finally, one bubble pulsation and the other bubble stationary make the bubbles repel each other.

Phosphorous-doped hydrogenated nanocrystalline silicon oxide (n-nc-SiO x :H) films are prepared via radio frequency plasma enhanced chemical vapor deposition (RF-PECVD). Increasing deposition power during n-nc-SiO x :H film growth process can enhance the formation of nanocrystalline and obtain a uniform microstructure of n-nc-SiO x :H film. In addition, in 20s interval before increasing the deposition power, high density small grains are formed in amorphous SiO x matrix with higher crystalline volume fraction (I c) and have a lower lateral conductivity. This uniform microstructure indicates that the higher I c can leads to better vertical conductivity, lower refractive index, wider optical band-gap. It improves the back reflection in a-Si:H/a-SiGe:H tandem solar cells acting as an n-nc-SiO x :H back reflector prepared by the gradient power during deposition. Compared with the sample with SiO x back reflector, with a constant power used in deposition process, the sample with gradient power SiO x back reflector can enhance the total short-circuit current density (J sc) and the initial efficiency of a-Si:H/a-SiGe:H tandem solar cells by 8.3% and 15.5%, respectively.

tics by varying the interaction length when pumping a PPLN crystal with fs pulses. (22) We studied the phase mismatched phenomenon resulting from the dispersion effect, by period- ically changing the polarity of crystal to obtain the optimal squeezing condition, and obtained the characteristic of EPR entanglements. (23) In this paper, we discuss the influence of the dispersion effect, find the solution of the time-dependent FPE with the dispersion, and investigate the entanglement characteristics for N = 2-5 partite. The investigation is es- pecially important for the pulse OPO and the quantum charac- teristics of pulse frequency combs.

An improved method of fitting point-by-point is proposed to determine the absorption coefficient from infrared (IR) transmittance. With no necessity of empirical correction factors, the absorption coefficient can be accurately determined for the films with thin thicknesses. Based on this method, the structural properties of the hydrogenated amorphous silicon oxide materials (a-SiOx:H) are investigated. The oxygen-concentration-dependent variation of the Si—O—Si and the Si—H related modes in a-SiOx:H materials is discussed in detail.

Three-dimensional (3D) nanostructures in thin film solar cells have attracted significant attention due to their applications in enhancing light trapping. Enhanced light trapping can result in more effective absorption in solar cells, thus leading to higher short-circuit current density and conversion efficiency. We develop randomly distributed and modified ZnO nanorods, which are designed and fabricated by the following processes: the deposition of a ZnO seed layer on substrate with sputtering, the wet chemical etching of the seed layer to form isolated islands for nanorod growth, the chemical bath deposition of the ZnO nanorods, and the sputtering deposition of a thin Al-doped ZnO (ZnO:Al) layer to improve the ZnO/Si interface. Solar cells employing the modified ZnO nanorod substrate show a considerable increase in solar energy conversion efficiency.

We investigate the dynamic characteristics of oil—gas—water three-phase flow in terms of chaotic attractor comparison. In particular, we extract a statistic to characterize the dynamical difference in attractor probability distribution. We first take time series from Logistic chaotic system with different parameters as examples to demonstrate the effectiveness of the method. Then we use this method to investigate the experimental signals from oil—gas—water three-phase flow. The results indicate that the extracted statistic is very sensitive to the change of flow parameters and can gain a quantitatively insight into the dynamic characteristics of different flow patterns.

The effects of annealing rate and morphology of sol—gel derived zinc oxide (ZnO) thin films on the performance of inverted polymer solar cells (IPSCs) are investigated. ZnO films with different morphologies are prepared at different annealing rates and used as the electron transport layers in IPSCs. The undulating morphologies of ZnO films fabricated at annealing rates of 10 °C/min and 3 °C/min each possess a rougher surface than that of the ZnO film fabricated at a fast annealing rate of 50 °C/min. The ZnO films are characterized by atomic force microscopy (AFM), optical transmittance measurements, and simulation. The results indicate that the ZnO film formed at 3 °C /min possesses a good-quality contact area with the active layer. Combined with a moderate light-scattering, the resulting device shows a 16% improvement in power conversion efficiency compared with that of the rapidly annealed ZnO film device.

In this paper, a-Si:H/a-SiGe:H/μc-SiGe:H triple-junction solar cell structure is proposed. By the analyses of microelectronic and photonic structures (AMPS-1D) and our TRJ-F/TRJ-M/TRJ-B tunneling-recombination junction (TRJ) model, the most preferably combined bandgap for this structure is found to be 1.85 eV/1.50 eV/1.0 eV. Using more realistic material properties, optimized thickness combination is investigated. Along this direction, a-Si:H/a-SiGe:H/μc-SiGe:H triple cell with an initial efficiency of 12.09% (Voc = 2.03 V, FF = 0.69, Jsc = 8.63 mA/cm2, area = 1 cm2) is achieved in our laboratory.

Hexagonal β-NaYF4 co-doped with Yb3+ and Er3+ is directly synthesized under mild conditions using a hydrothermal method. The variation of the ratio of Ln3+ to F− and ethylenediaminetetraacetic acid (EDTA) causes the shape of the microcrystal to change from microplate to microcolumn. The NaYF4 powder is mixed with polydimethylsiloxane (PDMS) to create an up-converter for thin film amorphous silicon solar cells so as to evaluate the effectiveness of the synthesized material as an up-converter. In order to overcome the difficulty in measuring the effectiveness of up-conversion material, a new method of using near infrared illumination to measure the short circuit current densities of solar cells both with and without up-converters is developed. An up-converter with pure hexagonal NaYF4:Yb3+/Er3+ microcrystal produces a high current output. Emission intensity data obtained by photoluminescence suggest that pure hexagonal NaYF4:Yb3+/Er3+ microcrystals are more efficient than nanocrystals when used as up-converting phosphors.