Analysis and Control of the Performance-Limiting Defects in HEM-Grown Silicon for Solar Cells

AbstractMulticrystalline silicon ingots of 55 cm × 55 cm cross section, 100 kg have been grown by the Heat Exchanger Method (HEM). Controlled growth features have been used to produce large grain size, vertically oriented grain boundaries, large areas of twins with low defect density and rejection of impurities to the top of the ingot. Ambient control has reduced C, N, and O concentration and minimized precipitates with no detectable metallic impurities. High performance solar cells have ben fabricated, and further improvements can be achieved by minimizing dislocation tangles and impurities in localized regions.

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Grain size control for high-performance formamidinium-based perovskite solar cells via suppressing heterogenous nucleation

Journal of Materials Chemistry C ◽

10.1039/d0tc04833j ◽

2021 ◽

Vol 9 (1) ◽

pp. 208-213

Author(s):

Xiaoxiao Xu ◽

Yuhai Sun ◽

Dingchao He ◽

Zheng Liang ◽

Guozhen Liu ◽

...

Keyword(s):

Grain Size ◽

Solar Cells ◽

Homogeneous Nucleation ◽

High Performance ◽

Defect Density ◽

Perovskite Solar Cells ◽

Size Control ◽

Precursor Solution ◽

Grain Size Control ◽

Heterogenous Nucleation

By introducing ED and TAP into precursor solution, homogeneous nucleation is encouraged to occur and films with large grain size and lower defect density were obtained.

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Ambient Air Temperature Assisted Crystallization for Inorganic CsPbI2Br Perovskite Solar Cells

Molecules ◽

10.3390/molecules26113398 ◽

2021 ◽

Vol 26 (11) ◽

pp. 3398

Author(s):

Yi Long ◽

Kun Liu ◽

Yongli Zhang ◽

Wenzhe Li

Keyword(s):

Solar Cells ◽

Air Temperature ◽

High Performance ◽

Defect Density ◽

Perovskite Solar Cells ◽

Ambient Air ◽

Dark Phase ◽

High Quality ◽

Ambient Air Temperature ◽

Air Atmosphere

Inorganic cesium lead halide perovskites, as alternative light absorbers for organic–inorganic hybrid perovskite solar cells, have attracted more and more attention due to their superb thermal stability for photovoltaic applications. However, the humid air instability of CsPbI2Br perovskite solar cells (PSCs) hinders their further development. The optoelectronic properties of CsPbI2Br films are closely related to the quality of films, so preparing high-quality perovskite films is crucial for fabricating high-performance PSCs. For the first time, we demonstrate that the regulation of ambient temperature of the dry air in the glovebox is able to control the growth of CsPbI2Br crystals and further optimize the morphology of CsPbI2Br film. Through controlling the ambient air temperature assisted crystallization, high-quality CsPbI2Br films are obtained, with advantages such as larger crystalline grains, negligible crystal boundaries, absence of pinholes, lower defect density, and faster carrier mobility. Accordingly, the PSCs based on as-prepared CsPbI2Br film achieve a power conversion efficiency of 15.5% (the maximum stabilized power output of 15.02%). Moreover, the optimized CsPbI2Br films show excellent robustness against moisture and oxygen and maintain the photovoltaic dark phase after 3 h aging in an air atmosphere at room temperature and 35% relative humidity (R.H.). In comparison, the pristine films are completely converted to the yellow phase in 1.5 h.

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Suppressing Vacancy Defects and Grain Boundaries via Ostwald Ripening for High‐Performance and Stable Perovskite Solar Cells

Advanced Materials ◽

10.1002/adma.201904347 ◽

2019 ◽

Vol 32 (7) ◽

pp. 1904347 ◽

Cited By ~ 31

Author(s):

Yuqian Yang ◽

Jihuai Wu ◽

Xiaobing Wang ◽

Qiyao Guo ◽

Xuping Liu ◽

...

Keyword(s):

Solar Cells ◽

Grain Boundaries ◽

High Performance ◽

Ostwald Ripening ◽

Perovskite Solar Cells ◽

Vacancy Defects

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Modulating the grain size, phase and optoelectronic quality of perovskite films with cesium iodide for high-performance solar cells

Journal of Materials Chemistry C ◽

10.1039/c8tc02923g ◽

2018 ◽

Vol 6 (29) ◽

pp. 7880-7889 ◽

Cited By ~ 10

Author(s):

Siraj Sidhik ◽

Andrea Cerdán Pasarán ◽

Christopher Rosiles Pérez ◽

Tzarara López-Luke ◽

Elder De la Rosa

Keyword(s):

Grain Size ◽

Solar Cells ◽

High Performance ◽

Smooth Surface ◽

Cesium Iodide

The role of cesium in retarding perovskite crystallization for enhanced grain size and ultra-smooth surface giving an efficiency of ∼19%.

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Enhanced Grain Size and Crystallinity in CH3NH3PbI3 Perovskite Films by Metal Additives to the Single-Step Solution Fabrication Process

MRS Advances ◽

10.1557/adv.2018.413 ◽

2018 ◽

Vol 3 (55) ◽

pp. 3237-3242 ◽

Cited By ~ 9

Author(s):

Zahrah S. Almutawah ◽

Suneth C. Watthage ◽

Zhaoning Song ◽

Ramez H. Ahangharnejhad ◽

Kamala K. Subedi ◽

...

Keyword(s):

Grain Size ◽

Solar Cells ◽

High Performance ◽

High Efficiency ◽

Perovskite Solar Cells ◽

Precursor Solution ◽

Single Step ◽

Fabrication Process ◽

Lead Iodide ◽

Methylammonium Lead Iodide

ABSTRACTMethods of obtaining large grain size and high crystallinity in absorber materials play an important role in fabrication of high-performance methylammonium lead iodide (MAPbI3) perovskite solar cells. Here we study the effect of adding small concentrations of Cd2+, Zn2+, and Fe2+salts to the perovskite precursor solution used in the single-step solution fabrication process. Enhanced grain size and crystallinity in MAPbI3 films were obtained by using 0.1% of Cd2+ or Zn2+in the precursor solution. Consequently, solar cells constructed with Cd- and Zn-doped perovskite films show a significant improvement in device performance. These results suggest that the process may be an effective and facile method to fabricate high-efficiency perovskite photovoltaic devices.

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Can Grain Boundaries Improve the Performance of Cu(In,Ga)Se2 Solar Cells?

MRS Proceedings ◽

10.1557/proc-1012-y09-01 ◽

2007 ◽

Vol 1012 ◽

Author(s):

Uwe Rau ◽

Uwe Rau

Keyword(s):

Solar Cells ◽

Grain Boundary ◽

Grain Boundaries ◽

High Performance ◽

Band Offset ◽

Device Performance ◽

Localized Defects ◽

Recombination Centers ◽

Numerical Device ◽

Large Charge

AbstractTwo-dimensional numerical device simulations investigate the influence of grain boundaries on the performance of Cu(In,Ga)Se2 solar cells focussing on the question whether or not grain boundaries can improve the efficiency of those devices. The results unveil the following statements: (i) The mere introduction of a grain boundary by adding localized defects into a device that has a high performance from the beginning is not beneficial. (ii) Polycrystalline solar cells can outperform monocrystalline ones, if the total number of defects is equal in both devices. I.e. a given number of recombination centers is better dealt with if these defects are concentrated at the grain boundary rather than homogeneously distributed in the bulk. (iii) A significant improvement of carrier collection via the grain boundaries is found if the bulk of the devices is assumed as relatively poor. In this situation, addition of defects that are not much recombination ac-tive but provide a large charge density at the grain boundaries can improve the device performance. (iv) Passivation of grain boundaries by an internal band offset in the valence band is effective only if the internal barrier amounts at least to 300 meV.

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Study of Metallurgy and Mechanical Property on Japanese Sword

Materials Science Forum ◽

10.4028/www.scientific.net/msf.738-739.222 ◽

2013 ◽

Vol 738-739 ◽

pp. 222-227 ◽

Cited By ~ 4

Author(s):

Muneo Yaso ◽

Yoshihiro Minagi ◽

Toshifumi Takaiwa ◽

Kunichika Kubota ◽

Tsuyoshi Kanaizumi ◽

...

Keyword(s):

Grain Size ◽

Cross Section ◽

High Performance ◽

Bending Strength ◽

Lath Martensite ◽

Bending Test ◽

Sharp Edge ◽

Tool Steels ◽

The Difference ◽

The Ideal

Japanese sword has finer grain size and lath martensite in the microstructure of sharp edge amazingly. Nowadays these structures are considered to be one of the ideal structure at which are greatly aimed to strengthen or improve toughness of steels. Though the carbon content of its sharp edge is 0.70 mass %, there are no lenticular martensite and no micocracking in that area. As a result of bending test by actual sword specimen, one sword was finally bent, the other sword was broken. However it is found the sharp edge in Japanese sword has such a large bending strength 2500, 4600MPa respectively as modern, high performance tool steels and the difference of crack propagation under bending depends on the microstructure distribution and the grain size in cross section of Japanese sword.

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Nucleation and Grain Boundaries in Thin Film CdTe/CdS Solar Cells

MRS Proceedings ◽

10.1557/proc-1165-m06-01 ◽

2009 ◽

Vol 1165 ◽

Cited By ~ 4

Author(s):

Jon D Major ◽

Yuri Y Proskuryakov ◽

Ken Durose

Keyword(s):

Grain Size ◽

Solar Cells ◽

Grain Boundaries ◽

Early Stage ◽

Formation Mechanisms ◽

Island Growth ◽

Secondary Nucleation ◽

Island Nucleation ◽

Equivalent Circuit Parameters ◽

Sublimation Growth

AbstractThe early stage formation mechanisms operating during the sublimation growth of CdTe films on CdS has been evaluated using a growth interrupt methodology for deposition under 100 Torr of N2. Key stages of the growth were identified and are discussed in terms of the processes of island nucleation, island growth/coalescence, channel formation and secondary nucleation that have been reported for other materials systems. It was demonstrated that the grain size could be manipulated by means of controlling the gas pressure in the range 2 – 200 Torr, with the grain diameter increasing with pressure linearly as D (μm) = 0.027(± 0.011) × P (Torr) + 0.90(± 0.31). For a series of solar cells made using such material, the performance parameters were seen to increase with grain size up to a plateau corresponding to grains of ∼4 μm in this case. Equivalent circuit parameters for resistive components arising from grain boundaries, and the contact to the CdTe, were measured. It is considered that grain boundary barriers in CdTe are harmful to PV performance, and that the plateau in performance occurs when the grain size is increased to the level where the contact resistance is greater than that due to grain boundaries.

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Defect Study of Polycrystalline–silicon Seed Layers made by Aluminum Induced Crystallization

MRS Proceedings ◽

10.1557/proc-1153-a16-02 ◽

2009 ◽

Vol 1153 ◽

Author(s):

Srisaran Venkatachalam ◽

Dries Van Gestel ◽

Ivan Gordon

Keyword(s):

Thin Film ◽

Solar Cells ◽

Grain Boundaries ◽

Seed Layer ◽

Polycrystalline Silicon ◽

Defect Density ◽

Sem Images ◽

Induced Crystallization ◽

Seed Layers ◽

Aluminum Induced Crystallization

AbstractA polycrystalline silicon (pc-Si) thin film with large grains on a low-cost non-Si substrate is a promising material for thin-film solar cells. One possibility to grow such a pc-Si layer is by aluminum-induced crystallization (AIC) followed by epitaxial thickening. The best cell efficiency we have achieved so far with such an AIC approach is 8%. The main factor that limits the efficiency of our pc-Si solar cells at present is the presence of many intra-grain defects. These intra-grain defects originate within the AIC seed layer. The defect density of the layers can be determined by chemical defect etching. This technique is well suited for our epitaxial layers but relatively hard to execute directly on the seed layers. This paper presents a way to reveal the defects present in thin and highly-aluminum-doped AIC seed layers by using defect etching. We used diluted Schimmel and diluted Wright etching solutions. SEM pictures show the presence of intra-grain defects and grain boundaries in seed layers after defect etching, as verified by EBSD analyses. The SEM images of diluted Wright etched pc-Si seed layer shows that grain boundaries become much better visible than with diluted Schimmel etch.

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