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Hayato Kawasaki

Bio: Hayato Kawasaki is an academic researcher from Kaneka Corporation. The author has contributed to research in topics: Solar cell & Silicon. The author has an hindex of 4, co-authored 16 publications receiving 1785 citations.

Papers
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Journal ArticleDOI
TL;DR: In this paper, a silicon heterojunction with interdigitated back contacts was presented, achieving an efficiency of 26.3% and a detailed loss analysis to guide further developments.
Abstract: The efficiency of silicon solar cells has a large influence on the cost of most photovoltaics panels. Here, researchers from Kaneka present a silicon heterojunction with interdigitated back contacts reaching an efficiency of 26.3% and provide a detailed loss analysis to guide further developments.

2,052 citations

Journal ArticleDOI
TL;DR: In this paper, a heterojunction interdigitated back contact solar cell with conversion efficiency of 26.6% was developed, which was independently confirmed by Fraunhofer Institute for Solar Energysystem Callab.

394 citations

Patent
20 Sep 2017
TL;DR: In this paper, the first and second electrodes are spaced apart from each other, and the first electrodes include a plurality of regions isolated from one another by the second electrodes disposed there.
Abstract: A solar cell includes: first conductivity-type layers and second conductivity-type layers each provided on a rear surface of a semiconductor substrate; first electrodes provided on the first conductivity-type layers; and second electrodes provided on the second conductivity-type layers The first electrodes and the second electrodes are spaced apart from each other, and the first electrodes include a plurality of regions isolated from one another by the second electrodes disposed therebetween Each of the plurality of regions of the first electrodes includes a non-mounting electrode section and a wiring-mounting electrode section having a larger electrode height than the non-connection electrode section In two adjacent first electrode regions, an imaginary line connecting the top of the wiring-mounting electrode section of one of the regions and the top of the wiring-mounting electrode section of the other region does not cross the second electrode disposed between the two regions

8 citations

Patent
09 Nov 2015
TL;DR: In this paper, a method of manufacturing a crystal silicon solar battery that has a conduction type single crystal silicon substrate 1, an inverse conduction-type silicon-based layer 3a and a first transparent electrode layer 4a which are provided on a first primary face of the substrate in this order, and a second primary face side electrode layer 8 at a secondprimary face side side.
Abstract: PROBLEM TO BE SOLVED: To provide a silicon solar battery that can reduce leak current and increase a conversion efficiency, and a manufacturing method for the same.SOLUTION: A method of manufacturing a crystal silicon solar battery that has a conduction type single crystal silicon substrate 1, an inverse conduction type silicon-based layer 3a and a first transparent electrode layer 4a which are provided on a first primary face of the substrate in this order, and a second primary face side electrode layer 8 at a second primary face side, comprises: a first transparent electrode layer forming step for forming a first transparent electrode layer on the first primary face of the inverse conduction type silicon-based layer, and a cleaving step of cleaving a crystal silicon solar battery product having a first transparent electrode layer in progress into plural parts in this order. The method further comprises an opening area forming step of forming a first transparent electrode layer opening area having no first transparent electrode layer on the first primary face side surface of the substrate before the cleaving step. The cleaving step preferably contains a laser irradiating step of irradiating the first transparent electrode layer opening area with a laser beam so that at least a part of the substrate is exposed from the first primary face side.

4 citations

Patent
15 Jun 2016
TL;DR: In this paper, a solar cell module having a crystalline silicon solar cell (4) and an interconnector (3) that is electrically connected to the solar cell is presented.
Abstract: Provided is a solar cell module having a crystalline silicon solar cell (4) and an interconnector (3) that is electrically connected to the crystalline silicon solar cell. The interconnector has a width of greater than or equal to 50 µm and less than 400 µm, and is disposed so as to electrically connect a plurality of finger electrodes while crossing the same. The crystalline silicon solar cell has a plurality of finger electrodes (9) that are provided in parallel arrangement on a photoelectric conversion unit (50), and is provided with an insulating layer (8) so as to cover a primary surface of the photoelectric conversion unit and the finger electrodes. In portions where the finger electrodes intersect with the interconnector, the finger electrodes and the interconnector are electrically connected through an opening provided in the insulating layer between each finger electrode and the interconnector.

3 citations


Cited by
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Journal ArticleDOI
TL;DR: In this paper, an organic halide salt phenethylammonium iodide (PEAI) was used on HC(NH2)2-CH3NH3 mixed perovskite films for surface defect passivation.
Abstract: In recent years, the power conversion efficiency of perovskite solar cells has increased to reach over 20%. Finding an effective means of defect passivation is thought to be a promising route for bringing further increases in the power conversion efficiency and the open-circuit voltage (VOC) of perovskite solar cells. Here, we report the use of an organic halide salt phenethylammonium iodide (PEAI) on HC(NH2)2–CH3NH3 mixed perovskite films for surface defect passivation. We find that PEAI can form on the perovskite surface and results in higher-efficiency cells by reducing the defects and suppressing non-radiative recombination. As a result, planar perovskite solar cells with a certificated efficiency of 23.32% (quasi-steady state) are obtained. In addition, a VOC as high as 1.18 V is achieved at the absorption threshold of 1.53 eV, which is 94.4% of the Shockley–Queisser limit VOC (1.25 V). Planar perovskite solar cells that have been passivated using the organic halide salt phenethylammonium iodide are shown to have suppressed non-radiative recombination and operate with a certified power conversion efficiency of 23.3%.

3,064 citations

Journal ArticleDOI
14 Sep 2018-Science
TL;DR: In this article, a semi-empirical model analysis and using the tandem cell strategy to overcome the low charge mobility of organic materials, leading to a limit on the active-layer thickness and efficient light absorption was performed.
Abstract: Although organic photovoltaic (OPV) cells have many advantages, their performance still lags far behind that of other photovoltaic platforms. A fundamental reason for their low performance is the low charge mobility of organic materials, leading to a limit on the active-layer thickness and efficient light absorption. In this work, guided by a semi-empirical model analysis and using the tandem cell strategy to overcome such issues, and taking advantage of the high diversity and easily tunable band structure of organic materials, a record and certified 17.29% power conversion efficiency for a two-terminal monolithic solution-processed tandem OPV is achieved.

2,165 citations

Journal ArticleDOI
10 Nov 2017-Science
TL;DR: Because photocurrents are near the theoretical maximum, the focus is on efforts to increase open-circuit voltage by means of improving charge-selective contacts and charge carrier lifetimes in perovskites via processes such as ion tailoring.
Abstract: The efficiencies of perovskite solar cells have gone from single digits to a certified 22.1% in a few years' time. At this stage of their development, the key issues concern how to achieve further improvements in efficiency and long-term stability. We review recent developments in the quest to improve the current state of the art. Because photocurrents are near the theoretical maximum, our focus is on efforts to increase open-circuit voltage by means of improving charge-selective contacts and charge carrier lifetimes in perovskites via processes such as ion tailoring. The challenges associated with long-term perovskite solar cell device stability include the role of testing protocols, ionic movement affecting performance metrics over extended periods of time, and determination of the best ways to counteract degradation mechanisms.

1,371 citations

Journal ArticleDOI
TL;DR: An optimized two-step deposition process allows the formation of uniform layers of metal halide perovskites on textured silicon layers, enabling tandem silicon/perovskite solar cells with improved optical design and efficiency.
Abstract: Tandem devices combining perovskite and silicon solar cells are promising candidates to achieve power conversion efficiencies above 30% at reasonable costs. State-of-the-art monolithic two-terminal perovskite/silicon tandem devices have so far featured silicon bottom cells that are polished on their front side to be compatible with the perovskite fabrication process. This concession leads to higher potential production costs, higher reflection losses and non-ideal light trapping. To tackle this issue, we developed a top cell deposition process that achieves the conformal growth of multiple compounds with controlled optoelectronic properties directly on the micrometre-sized pyramids of textured monocrystalline silicon. Tandem devices featuring a silicon heterojunction cell and a nanocrystalline silicon recombination junction demonstrate a certified steady-state efficiency of 25.2%. Our optical design yields a current density of 19.5 mA cm−2 thanks to the silicon pyramidal texture and suggests a path for the realization of 30% monolithic perovskite/silicon tandem devices.

990 citations