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N-type microcrystalline silicon carbide (μc-SiC:H(n)) is a wide bandgap material that is very promising for the use on the front side of crystalline silicon (c-Si) solar cells. It offers a high optical transparency and a suitable refractive index that reduces parasitic absorption and reflection losses, respectively. In this work, we investigate the potential of hot wire chemical vapor deposition (HWCVD)–grown μc-SiC:H(n) for c-Si solar cells with interdigitated back contacts (IBC). We demonstrate outstanding passivation quality of μc-SiC:H(n) on tunnel oxide (SiO2)–passivated c-Si with an implied open-circuit voltage of 742 mV and a saturation current density of 3.6 fA/cm2. This excellent passivation quality is achieved directly after the HWCVD deposition of μc-SiC:H(n) at 250°C heater temperature without any further treatments like recrystallization or hydrogenation. Additionally, we developed magnesium fluoride (MgF2)/silicon nitride (SiNx:H)/silicon carbide antireflection coatings that reduce optical losses on the front side to only 0.47 mA/cm2 with MgF2/SiNx:H/μc-SiC:H(n) and 0.62 mA/cm2 with MgF2/μc-SiC:H(n). Finally, calculations with Sentaurus TCAD simulation using MgF2/μc-SiC:H(n)/SiO2/c-Si as front side layer stack in an IBC solar cell reveal a short-circuit current density of 42.2 mA/cm2, an open-circuit voltage of 738 mV, a fill factor of 85.2% and a maximum power conversion efficiency of 26.6%.

Eriocitrin, a main flavonoid in lemons, possesses strong antioxidant, lipid-lowering and anticancer activities and has long been used in food, beverages and wine. However, its metabolism in vivo and in vitro is still unclear. In this study, an efficient strategy was developed to detect and identify metabolites of eriocitrin by using ultra-high-performance liquid chromatography coupled with hybrid triple quadrupole time-of-flight mass spectrometry (UHPLC-Q-TOF-MS) based on online data acquisition and multiple data processing techniques. A total of 32 metabolites in vivo and 27 metabolites in vitro were obtained based on the above method. Furthermore, the main metabolic pathways of eriocitrin included reduction, hydrogenation, N-acetylation, ketone formation, oxidation, methylation, sulfate conjugation, glutamine conjugation, glycine conjugation, desaturation and demethylation to carboxylic acid. This study will lay a foundation for further studies on the metabolic mechanisms of eriocitrin.

Summary In order to compensate the insufficient conductance of heterojunction thin films, transparent conductive oxides (TCO) have been used for decades in both sides of contacted crystalline silicon heterojunction (SHJ) solar cells to provide lateral conduction for carrier collection. In this work, we substitute the TCO layers by utilizing the lateral conduction of c-Si absorber, thereby enabling a TCO-free design for SHJ solar cells achieving a low series resistivity of 0.32 Ωcm2 and a good fill factor of 80.7% with a conventional finger pitch of 1.8 mm. Achieving high efficiencies in TCO-free SHJ solar cells requires suppressing deterioration of the passivation quality induced by the direct metal-to-a-Si:H contacts. We show that an ozone treatment at the a-Si:H/metal interface suppresses the metal diffusion into the a-Si:H layer and improves the passivation without increasing the contact resistivity. SHJ solar cells with TCO-free front contacts and ozone treatment achieve efficiencies of >22%.

Nature energy (2021). doi:10.1038/s41560-021-00806-9, Published by Nature Publishing Group, London

Conductive hydrogenated silicon carbide (SiCx:H) is discovered as a promising hydrogenation material for tunnel oxide passivating contacts (TOPCon) solar cells. The proposed SiCx:H layer enables a good passivation quality and features a good electrical conductivity, which eliminates the need of etching back of SiNx:H and indium tin oxide (ITO)/Ag deposition for metallization and reduces the number of process steps. The SiCx:H is deposited by hot wire chemical vapor deposition (HWCVD) and the filament temperature (Tf) during deposition is systematically investigated. Via tuning the SiCx:H layer, implied open-circuit voltages (iVoc) up to 742 ± 0.5 mV and a contact resistivity (ρc) of 21.1 ± 5.4 mΩ·cm2 is achieved using SiCx:H on top of poly-Si(n)/SiOx/c-Si(n) stack at Tf of 2000 °C. Electrochemical capacitance–voltage (ECV) and secondary ion mass spectrometry (SIMS) measurements were conducted to investigate the passivation mechanism. Results show that the hydrogenation at the SiOx/c-Si(n) interface is responsible for the high passivation quality. To assess its validity, the TOPCon stack was incorporated as rear electron selective-contact in a proof-of-concept n-type solar cells featuring ITO/a-Si:H(p)/a-Si:H(i) as front hole selective-contact, which demonstrates a conversion efficiency up to 21.4%, a noticeable open-circuit voltage (Voc) of 724 mV and a fill factor (FF) of 80%.

A highly transparent front contact layer system for crystalline silicon (c-Si) solar cells is investigated and optimized. This contact system consists of a wet-chemically grown silicon tunnel oxide, a hydrogenated microcrystalline silicon carbide [SiO2/µc-SiC:H( n )] prepared by hot-wire chemical vapor deposition (HWCVD), and a sputter-deposited indium doped tin oxide. Because of the exclusive use of very high bandgap materials, this system is more transparent for the solar light than state of the art amorphous (a-Si:H) or polycrystalline silicon contacts. By investigating the electrical conductivity of the µc-SiC:H( n ) and the influence of the hot-wire filament temperature on the contact properties, we find that the electrical conductivity of µc-SiC:H( n ) can be increased by 12 orders of magnitude to a maximum of 0.9 S/cm due to an increased doping density and crystallite size. This optimization of the electrical conductivity leads to a strong decrease in contact resistivity. Applying this SiO2/µc-SiC:H( n ) transparent passivating front side contact to crystalline solar cells with an a-Si:H/c-Si heterojunction back contact we achieve a maximum power conversion efficiency of 21.6% and a short-circuit current density of 39.6 mA/cm2. All devices show superior quantum efficiency in the short wavelength region compared to the reference cells with a-Si:H/c-Si heterojunction front contacts. Furthermore, these transparent passivating contacts operate without any post processing treatments, e.g., forming gas annealing or high-temperature recrystallization.

The purpose of this study is to develop semi-transparent perovskite solar cells using graphene electrodes for high-efficiency tandem application. Two layers of graphene was considered optimum for perovskite solar cells, and this was confirmed by evaluating the optical and electrical performance. The tandem cells were further studied by controlling the thickness of perovskite films using different spin speeds, and 3000 rpm was considered the optimum speed. The bandgap of Cl-doped perovskite thin films was 1.59 eV. Measurement of morphology and crystal structure confirmed a good level of crystallinity. This study also examined both the optical and electrical performance of the semi-transparent perovskite solar cells, to optimize the power conversion efficiency (PCE) of the tandem application using silicon solar cells. To the best of our knowledge, the tandem cells demonstrated a total PCE of 18.1%, which is the highest value among those of other cells that have the same structure as that of tandem cells.

In 2 O 3 thin films were prepared by reactive evaporation with post-annealing treatment at forming gas of N 2 and H 2 . After post-annealing treatment, the films annealed at forming gas achieved lowest resistivity of 2.70 × 10 −4 Ω cm. The XRD results show that the In 2 O 3 films annealed in forming gas and N 2 with good recrystallization. In the forming gas annealing process, hydrogen plays a key role in the generation of oxygen vacancies and enhances the formation of In–OH bond which may influence the electrical and optical properties of the In 2 O 3 films.

The morphology, optical and composition properties of Zinc sulfide (ZnS) thin films prepared by thermal evaporation method were investigated. The as-deposited ZnS thin films exhibited good smoothness and showed (1 1 1) preferential orientation. The atomic concentrations of Zn = 49.98% and S = 50.02% were calculated from the XPS spectrum. Band-gap of 3.72 eV was deduced from the optical transmittance spectra. The power conversion efficiency (PCE) of the hydrogen doped AZO (HAZO)/ZnS/textured p-Si heterojunction solar cells was η = 8.83%, which is the best so far to our knowledge. The solar cell without encapsulation exhibited no degradation for more than 2400 h, indicating the good stability of the device.

The transition metal-oxide thin films of WO 3 have been prepared by thermal evaporation at a low deposition rate. The material characterization shows that the thin films have stoichiometric composition and the tungsten ions were fully oxidised into W 6+ . The surface of the WO 3 thin films became smoother when the thickness increased. The results show that the deposition of WO 3 thin film follows island growth. The flatband voltage of WO 3 /Si was extracted. The values on n-Si and p-Si were about 0.75 eV and 0 eV, respectively. It was also found that large amounts of negative charges were accumulated at the interface of WO 3 /n-Si because of electron transfer.

Hot-wire chemical vapor deposition was used to deposit in situ-doped amorphous silicon layers for poly-Si/SiOx passivating contacts at a high deposition rate of 42 nm/min. We investigated the influence of a varied phosphine gas (PH3) concentration during deposition on (i) the silicon film properties and (ii) the passivating contact performances. The microstructural film properties were characterized before and after a high-temperature crystallization step to transform amorphous silicon films into polycrystalline silicon films. Before crystallization, the silicon layers become less dense as the PH3 concentrations increase. After crystallization, an increasing domain size is derived for higher PH3 concentrations. Sheet resistance is found to decrease as domain size increased, and the correlation between mobility and domain size was discussed. The performances of the passivating contact were measured, and a firing stable open circuit voltage of 732 mV, a contact resistivity of 8.1 mΩ·cm2, and a sheet resistance of 142 Ω/□ could be achieved with the optimized PH3 concentration. In addition, phosphorous doping tails into the crystalline silicon were extracted to evaluate the Auger recombination of the passivating contact.

The purpose of this work is to investigate the passivating and conducting layers of crystalline silicon solar cells. The Al 2 O 3 /Ag/Al 2 O 3 stack was chosen because of the free carrier injection effect of this structure. A resistivity as low as 2.81 × 10 − 5 Ω cm was achieved with a 16 nm Ag interlayer. The current-voltage measurements indicate that the current density increases with the increasing thickness of the Ag layers. The passivation properties of the stacks were examined by effective minority carrier lifetime measurements. The annealing process was applied to study the thermal stability of the thin film stacks. The best sample yielded an effective surface recombination velocity of approximately 50 cm/s and a resistivity of approximately 3.0 × 10 − 5 Ω cm. Moreover, the fixed charges of the investigated structures varied according to the thickness of the Ag layers. The experimental results demonstrated the promising potential of Al 2 O 3 /Ag/Al 2 O 3 stacks as passivating and conducting layers for crystalline silicon solar cells.

Hot-wire chemical vapor deposition (HWCVD) was utilized to develop a fast and high quality a-Si:H thin film fabrication method for poly-Si/SiOx carrier selective passivating contacts targeting at n-type passivated emitter rear totally diffused crystalline silicon solar cells. The microstructure and hydrogen content of the a-Si:H thin films were analyzed by Fourier-transform infrared spectroscopy in order to understand the influence of film properties on passivation and conductivity. Dense layers were found to be beneficial for good passivation. On the other hand, blistering appeared as a-Si:H layers became more and more dense. However, by adjusting the SiH4 flow rate and the substrate heater temperature, blistering of a-Si:H could be avoided. A suitable process window was found and firing-stable implied open circuit voltage (iVoc) of up to 738 mV was achieved. In addition to high iVoc, a low contact resistivity of 0.034 Ω cm2 was also achieved. The deposition rate of the a-Si:H layers was 7 A/s by using HWCVD, which is one order of magnitude higher than the deposition rate reported using other deposition methods.Hot-wire chemical vapor deposition (HWCVD) was utilized to develop a fast and high quality a-Si:H thin film fabrication method for poly-Si/SiOx carrier selective passivating contacts targeting at n-type passivated emitter rear totally diffused crystalline silicon solar cells. The microstructure and hydrogen content of the a-Si:H thin films were analyzed by Fourier-transform infrared spectroscopy in order to understand the influence of film properties on passivation and conductivity. Dense layers were found to be beneficial for good passivation. On the other hand, blistering appeared as a-Si:H layers became more and more dense. However, by adjusting the SiH4 flow rate and the substrate heater temperature, blistering of a-Si:H could be avoided. A suitable process window was found and firing-stable implied open circuit voltage (iVoc) of up to 738 mV was achieved. In addition to high iVoc, a low c...