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%.

Surface passivation of perovskite film for efficient solar cells

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.

https://science.sciencemag.org/content/sci/early/2018/08/08/science.aat2612.full.pdf

Organic and solution-processed tandem solar cells with 17.3% efficiency

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.

Silicon heterojunction solar cell with interdigitated back contacts for a photoconversion efficiency over 26

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.

http://science.sciencemag.org/content/sci/358/6364/739.full.pdf

Promises and challenges of perovskite solar cells

ZnS nanostructures: From synthesis to applications

PROBLEM TO BE SOLVED: To enhance the conversion efficiency of a solar cell, and to reduce the manufacturing cost of a solar cell module.SOLUTION: A solar cell has a photoelectric conversion part, and a collector electrode 7 on one principal surface of the photoelectric conversion part. The collector electrode includes a first conductive layer 71 and a second conductive layer 72, in this order, from the photoelectric conversion part side, and includes an insulation layer 9 having an opening between the first conductive layer and second conductive layer. The first conductive layer is covered with the insulation layer, and a part of the second conductive layer conducts with the first conductive layer through the opening of the insulation layer. Preferably, following relationship is satisfied; Ra2=1.0-10.0 μm, Ra1>Ra2, where Ra1 and Ra2 are the surface roughness of the first conductive layer and second conductive layer.

Solar cell and manufacturing method therefor, and solar cell module

PROBLEM TO BE SOLVED: To improve the conversion efficiency of a solar battery.SOLUTION: A solar battery comprises a photoelectric conversion part, and a collecting electrode on one principal surface of the photoelectric conversion part. The photoelectric conversion part has a reverse conductive type silicon-based thin film and a first transparent electrode layer in that order on the first principal surface of one conductive crystal silicon substrate, and has one conductive type silicon-based thin film and a back surface electrode layer in that order on the second principal surface of the substrate. The photoelectric conversion part has, on the first principal surface and a side face thereof, an insulation area from which a short-circuit between the first transparent electrode layer on the first principal surface side and the rear surface electrode layer on the second principal surface side is eliminated. The insulation area satisfies W1<W2 if the width of the first principal surface and second principal surface of the photoelectric conversion part are represented by W1 and W2 respectively. Additionally, it is preferable that the insulation area have a shoulder structure over the peripheral edge parts and side faces of the first principal surface of the photoelectric conversion part so as to expose the substrate.

Solar battery, manufacturing method for the same, and solar battery module

29.2%-conversion efficiency of a two-terminal (2T) perovskite/crystalline Si heterojunction tandem solar cell using 145 μm thick industrial Czochralski (CZ) Si wafer is obtained. The structural optimization, such as surface passivation of the perovskite layer and better light management techniques, improved power conversion efficiency (PCE). To our knowledge, this PCE is the best in 2T-tandem solar cells using CZ wafers. Towards industrialization, crucial issues with the 2T tandem solar cells with crystalline Si bottom cell are discussed. Four-terminal (4T) tandem solar cells are evaluated as an approach to avoid the crucial issues. Examining our base technologies which realize 22.2%-conversion efficiency perovskite single junction solar cell module and 26%-heterojunction back-contact solar cells, we clarified that the based technologies were ready to realize 30%-conversion efficiency 4T perovskite/heterojunction crystalline Si tandem solar cells with approximately quarter size of an industrial crystalline Si solar cell (∼64 cm2).

https://iopscience.iop.org/article/10.35848/1347-4065/acc593/pdf

High efficiency perovskite/heterojunction crystalline silicon tandem solar cells: towards industrial-sized cell and module

Provided is a method for producing a solar cell, which enables simplification of the production of solar cells, while suppressing decrease in the performance of the solar cells A method for producing a solar cell according to the present invention is a method for producing a backside electrode type solar cell 1 which is provided with a semiconductor substrate 11, an intrinsic semiconductor layer 23, a first conductivity type semiconductor layer 25, a second conductivity type semiconductor layer 35, a first electrode layer 27 and a second electrode layer 37 This method for producing a solar cell comprises: a first conductivity type semiconductor layer formation step wherein after the formation of a first conductivity type semiconductor material film on the intrinsic semiconductor layer 23 on one main surface of the semiconductor substrate 11, parts of the first conductivity type semiconductor material film and the intrinsic semiconductor layer 23 in the film thickness direction are removed by plasma etching with use of a mask, said parts corresponding to the opening of the mask; and a second conductivity type semiconductor layer formation step wherein the second conductivity type semiconductor layer 35 is formed on the intrinsic semiconductor layer 23 corresponding to the opening of the mask on the one main surface side of the semiconductor substrate 11

Method for producing solar cell, and solar cell

Provided is a solar cell manufacturing method, which can simplify the formation of a transparent electrode layer. The method of manufacturing a solar cell comprises, in the following order: a step for forming conductive semiconductor layers (25, 35) on the rear surface side of a substrate (11); a step for forming transparent conductive films on the conductive semiconductor layers (25, 35); a step for forming metal electrode layers (29, 39) on the conductive semiconductor layers (25, 35); and a step for forming transparent electrode layers (28, 38) by patterning the transparent conductive films. In the metal electrode layer forming step, a printing material is printed and cured to form resin films (40) obtained by unevenly distributing a resin material on the peripheries of the metal electrode layers (29, 39). In the metal electrode layers (29, 39), the proportion of a metal material contained in the printing material of upper metal electrode layers (29u, 39u) is smaller than that of lower metal electrode layers (29l, 39l). In the transparent electrode layer forming step, a transparent conductive film is patterned using, as a mask, the metal electrode layer (29), the resin film (40) on the periphery of the metal electrode layer (29), the metal electrode layer (39), and the resin film (40) on the periphery of the metal electrode layer (39).

Daisuke Adachi

Papers

Solar cell and manufacturing method therefor, and solar cell module

Solar battery, manufacturing method for the same, and solar battery module

High efficiency perovskite/heterojunction crystalline silicon tandem solar cells: towards industrial-sized cell and module

Method for producing solar cell, and solar cell

Solar cell manufacturing method and solar cell