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We investigated the effect of the B2H6plasma treatment on p-type hydrogenated amorphous silicon (p-a-Si:H) surfaces for high-performance silicon heterojunction (SHJ) solar cells. Secondary ion mass spectroscopy measurements revealed that the boron concentration at the p-a-Si:H surface is increased by employing the B2H6plasma treatment. Furthermore, specific contact resistance is decreased by about one-third after the B2H6plasma treatment. No degradation of passivation performance is induced by the B2H6plasma treatment. The power conversion efficiency of the SHJ solar cells with the B2H6plasma treatment is improved by the increase in fill factor (FF) due to decreased series resistance and increased shunt resistance. From numerical simulations, the upward band bending is enhanced at the heterointerface between transparent conductive oxide (TCO) and p-a-Si:H by the B2H6plasma treatment, which is responsible for the improved FF owing to facilitated tunneling holes from c-Si to p-a-Si:H layers and the TCO/p-a-Si:H heterointerface.

Functional carbon materials have recently attracted attention as positive electrode active materials for Al rechargeable batteries in conjunction with an Al negative electrode and a chloroaluminate ionic liquid electrolyte. This study explores a new carbon material, a graphene-decorated activated carbon fiber cloth (ACFC), for the positive electrode. Graphene-decorated ACFCs can be used in a binder-free manner and will directly contribute to increased gravimetric capacity of the whole electrode [mAh (gelectrode)[?]1, not per the active material]. Specifically, the positive electrode behaviors of three types of ACFC-based electrodes are examined in a Lewis acidic AlCl3[?]1-ethyl-3-methylimidazolioum chloride ([C2mim]Cl) room-temperature ionic liquid. Uncoated and low-loading graphene-coated ACFC electrodes show an electric double layer capacitor (EDLC)-like behavior, whereas the intercalation/deintercalation reaction of chloroaluminate anion (e.g., [AlCl4][?]) is observed for the high-loading graphene-coated one. These electrodes exhibit a good cyclability and satisfactory coulombic efficiency up to 800 cycles at a current density of 500 mA g[?]1.

Within this work, first bifacial silicon heterojunction solar cells with rotary screen printed front‐ and rear‐side metallization are demonstrated. The high‐throughput metallization process is carried out using an innovative rotary printing demonstrator machine with short process cycle times down to 0.65 s cell−1. Furthermore, a very low total silver consumption of only 6–9 mg Wp−1for the fully metallized bifacial silicon heterojunction solar cells is demonstrated. Using a newly developed screen simulation approach, the utilized fine line rotary and flatbed screens are analyzed regarding their suitability for fine line metallization and verified using in‐depth analysis of the geometrical and electrical properties of printed and cured metallization. The best group of fully rotary screen printed cells obtains a mean conversion efficiency of ηRSP,avg= 21.7% which is close to the flatbed screen printed reference group with ηFSP,avg= 22.1%. Using a hybrid approach with a rotary screen printed grid on the rear side and flatbed screen printed grid on the front side, a mean conversion efficiency of ηhyb,avg= 22.0% is obtained with a very low total silver consumption of only 9 mg Wp. This work successfully demonstrates a high‐throughput rotary screen printing process for the metallization of silicon heterojunction (SHJ) solar cells. Silver paste laydown is reduced by up to 70% while maintaing a closely similar I–Vperformance of the SHJ cells to the reference. A substantial reduction of the cycle time per wafer compared to the reference process is demonstrated. Image of rotary screen and mesh with permission from Gallus Group.

We evaluated the fill factor (FF) degradation mechanism in silicon heterojunction (SHJ) solar cells with high mobility In2O3film as a high carrier mobility transparent conductive oxide (TCO) film. In particular, we focused on the electrode formation using a high productive screen-printing technique. We found the In2O3film is easier to be reduced than the traditional TCO such as tin-doped indium oxide (ITO). Thus, the Ag atom inside the electrode is easily oxidized during the cure annealing process and results in higher contact resistance at electrode/TCO interface and deteriorate FF characteristic. We introduced novel cation catalyst additive for paste polymerization which is less reactive with In2O3and improve the contact resistance by suppressing the silver oxidation. We also demonstrated SHJ cell fabrication and prove the effect of the developed silver paste.

We investigated the interface phenomena between the electrode by a low fire-through electrode paste and the silicon substrate in a crystalline silicon solar cell. Oblique polishing was used to evaluate the chemical bonding states in the depth direction. From the evaluation by X-ray photoelectron spectroscopy (XPS) and the hard X-ray photoelectron spectroscopy (HAXPES), we found changes in the chemical bonding states of Ag 3d, Si 2p, O 1s, and N 1s at the electrode-silicon interface. In addition, it was possible to confirm the reduction of Ag induced by the heat treatment at the interface. Thus, it became possible to evaluate the chemical bonding states at the interface between the electrode and the silicon substrate by adapting oblique polishing and XPS measurement.

Functional carbon materials have recently attracted attention as positive electrode active materials for Al rechargeable batteries in conjunction with an Al negative electrode and a chloroaluminate ionic liquid electrolyte. This study explores a new carbon material, a graphene-decorated activated carbon fiber cloth (ACFC), for the positive electrode. Graphene-decorated ACFCs can be used in a binder-free manner and will directly contribute to increased gravimetric capacity of the whole electrode [mAh (gelectrode)−1, not per the active material]. Specifically, the positive electrode behaviors of three types of ACFC-based electrodes are examined in a Lewis acidic AlCl3−1-ethyl-3-methylimidazolioum chloride ([C2mim]Cl) room-temperature ionic liquid. Uncoated and low-loading graphene-coated ACFC electrodes show an electric double layer capacitor (EDLC)-like behavior, whereas the intercalation/deintercalation reaction of chloroaluminate anion (e.g., [AlCl4]−) is observed for the high-loading graphene-coated one. These electrodes exhibit a good cyclability and satisfactory coulombic efficiency up to 800 cycles at a current density of 500 mA g−1.

Ascorbic acid (AA) is a biologically friendly compound and exists in many products such as sports drinks, fruit, and even in human blood. Thus, a miniaturized and flexible ascorbic acid fuel cell (AAFC) is expected be a power source for portable or implantable electric devices. In this study, we fabricated an AAFC with anode and cathode dimensions of 3 x 10 mm2 made of a graphene-coated carbon fiber cloth (GCFC) and found that GCFC electrodes significantly improve the power generated by the AAFC. This is because the GCFC has more than two times the effective surface area of a conventional carbon fiber cloth and it can contain more enzymes. The power density of the AAFC in a phosphate buffer solution containing 100 mM AA at room temperature was 34.1 uW/cm2 at 0.46 V. Technical issues in applying the AAFC to portable devices are also discussed.

In this work, we fabricated flexible electrodes for a miniaturized, simple structured, and flexible glucose biofuel cell (BFC) using a graphene-coated carbon fiber cloth (GCFC). The areas of the anode and cathode electrodes were 3 x 10 mm2. The anode area was coated with the enzyme glucose oxidase, and the cathode area was coated with the enzyme bilirubin oxidase. No ion-exchange film was needed because glucose oxidase selectively oxidizes glucose and bilirubin oxidase selectively reduces oxygen. The power density of the BFC with GCFC electrodes in a phosphate buffer solution of 200 mM glucose solution at room temperature was 34.3 uW/cm2 at 0.43 V. The power density of a BFC using carbon fiber cloth (CFC) without graphene modification was 18.5 uW/cm2 at 0.13 V. The BFC with the GCFC electrode continued to function longer than 24 h with a power density higher than 5 uW/cm2. These effects were attributed to the much larger effective surface areas of the GCFC electrodes that maintain more enzymes than those of the CFC electrodes.

We have successfully fabricated a filament-less X-ray tube using a graphene flower cloth (GFC) field emission cathode. The GFC has numerous nanoprotrusions formed by self-standing graphene structures. The field emission current and the field enhancement factor ? were 500 µA and 5600, respectively. The stability of voltage defined as a variance coefficient (?/mean) of voltage was calculated to be 0.04% while maintaining the X-ray tube current of 300 µA. We applied our X-ray tube with the GFC field emitter to the X-ray fluorescence (XRF) analysis of stainless steel.