• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.427-427
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• 2016

Organic-inorganic hybrid perovskite have attracted significant attention as a new revolutionary light absorber for photovoltaic device due to its remarkable characteristics such as long charge diffusion lengths (100-1000nm), low recombination rate, and high extinction coefficient. Recently, power conversion efficiency of perovskite solar cell is above 20% that is approached to crystalline silicon solar cells. Planar heterojunction perovskite solar cells have simple device structure and can be fabricated low temperature process due to absence of mesoporous scaffold that should be annealed over 500 oC. However, in the planar structure, controlling perovskite film qualities such as crystallinity and coverage is important for high performances. Those controlling methods in one-step deposition have been reported such as adding additive, solvent-engineering, using anti-solvent, for pin-hole free perovskite layer to reduce shunting paths connecting between electron transport layer and hole transport layer. Here, we studied the effect of alkali metal halide to control the fabrication process of perovskite film. During the morphology determination step, alkali metal halides can affect film morphologies by intercalating with PbI2 layer and reducing $CH3NH3PbI3{\cdot}DMF$ intermediate phase resulting in needle shape morphology. As types of alkali metal ions, the diverse grain sizes of film were observed due to different crystallization rate depending on the size of alkali metal ions. The pin-hole free perovskite film was obtained with this method, and the resulting perovskite solar cells showed higher performance as > 10% of power conversion efficiency in large size perovskite solar cell as $5{\times}5cm$. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and inductively coupled plasma optical emission spectrometry (ICP-OES) are analyzed to prove the mechanism of perovskite film formation with alkali metal halides.

• Korean Journal of Materials Research
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• v.25 no.5
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• pp.233-237
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• 2015

Silicon oxynitride that can be deposited two times faster than general SiNx:H layer was applied to fabricate the passivation protection layer of atomic layer deposition (ALD) $Al_2O_3$. The protection layer is deposited by plasma-enhanced chemical vapor deposition to protect $Al_2O_3$ passivation layer from a high temperature metallization process for contact firing in screen-printed silicon solar cell. In this study, we studied passivation performance of ALD $Al_2O_3$ film as functions of process temperature and RF plasma effect in plasma-enhanced chemical vapor deposition system. $Al_2O_3$/SiON stacks coated at $400^{\circ}C$ showed higher lifetime values in the as-stacked state. In contrast, a high quality $Al_2O_3$/SiON stack was obtained with a plasma power of 400 W and a capping-deposition temperature of $200^{\circ}C$ after the firing process. The best lifetime was achieved with stack films fired at $850^{\circ}C$. These results demonstrated the potential of the $Al_2O_3/SiON$ passivated layer for crystalline silicon solar cells.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.36 no.4
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• pp.332-340
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• 2023

Crystalline silicon solar cells have attracted great attention for their various advantages, such as the availability of raw materials, high-efficiency potential, and well-established processing sequence. Tunnel oxide passivated contact (TOPCon) solar cells are widely regarded as one of the most prospective candidates for the next generation of high-performance solar cells because an efficiency of 26% has been achieved in small-area solar cells. Compared to n-type TOPCon solar cells, the photo conversion efficiency (PCE) of p-type TOPCon is slightly higher. The highest PCEs of p-type TOPCon and n-type TOPCon solar cells are 26.0% and 25.8%, respectively. Despite the highest efficiency in small-area cells, limited progress has been achieved in p-type TOPCon solar cells for large are due to their lower carrier lifetime and inferior surface passivation with the boron-doped c-Si wafer. Nevertheless, it is of great importance to promoting the p-type TOPCon technology due to its lower price and well-established manufacturing procedures with slight modifications in the PERC solar cells production lines. The progress in different approaches to increase the efficiencies of p-type TOPCon solar cells has been reported in this review article and is expected to set valuable strategies to promote the passivation technology of p-type TOPCon, which could further increase the efficiency of TOPCon solar cells.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.25 no.12
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• pp.1009-1014
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• 2012

Hydrogenated amorphous silicon (${\alpha}$-Si:H) layers deposited by plasma enhanced chemical vapor deposition (PECVD) are investigated for use in silicon hetero-junction solar cells employing n-type crystalline silicon (c-Si) substrates. The optical and structural properties of silicon hetero-junction devices have been characterized using spectroscopy ellipsometry and high resolution cross-sectional transmission electron micrograph (HRTEM). In addition, the effective carrier lifetime is measured by the quasi-steady-state photocoductance (QSSPC) method. We have studied on the correlation between the order of ${\alpha}$-Si:H and the passivation quality at the interface of ${\alpha}$-Si:H/c-Si. Base on the result, we have fabricated a silicon hetero-junction solar cell incorporating the ${\alpha}$-Si:H passivation layer with on open circuit voltage ($V_{oc}$) of 637 mV.

• 한국신재생에너지학회:학술대회논문집
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• 2010.06a
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• pp.72.1-72.1
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• 2010

Thin film a-Si solar cells deposited by PECVD have many advantages compared to the traditional crystalline Si solar cells. They do not require expensive Si wafer, the process temperature is relatively low, possibility of scaling up for mass production, etc. In order to produce thin film solar cells, understanding the relationship between the material characteristics and deposition conditions is important. It has been reported by many groups that the band gap of the a-Si material and the deposition rate has an linear relationship, when RF power is used to control both. However, when the process pressure is changed in order to control the deposition rate and the band gap, a diversion from the well known linear relationship occurs. Here, we explain this diversion by the deposition condition crossing different plasma regions in the Paschen curve with a simple model. This model will become a guide to which condition a-Si thin films must be fabricated in order to get a high quality film.

• Journal of the Korean Solar Energy Society
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• v.29 no.6
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• pp.88-93
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• 2009

This study was conducted to improve the power of PV module using a surface cooling system One of the unique characteristics of PV module is power drop as a module surface temperature increases due to the characteristics of crystalline silicon used in a solar cell. To overcome the output power reduction by temperature effect, module surface cooling using water circulation was performed. By cooling effect, module surface temperature drops maximally $20.3^{\circ}C$ predicting more than 10% power enhancement. Maximum deviation of voltage and current between a control and cooled module differed by 5.1 V and O.9A respectively. The maximum power enhancement by cooling system was 12.4% compared with a control module. In addition, cooling system can wash the module surface by water circulation so that extra power up of PV module can be achieved by removing particles on the surface which interfere solar radiation on the cells. Cooling system, besides, can reduce the maintenance cost and prevent accidents as a safety precaution while cleaning works. This system can be applied to the existing photovoltaic power generation facilities without any difficulties as well.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.32 no.3
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• pp.187-191
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• 2019

Advances in laser technology have enabled ultra-high-speed ultra-precise processing, thus expanding potential applications to the semiconductor, medical, and photovoltaic industries. In particular, laser scribing technology has been applied to the production of shingled solar modules. In this work, we analyze the effect of laser scribing conditions, e.g., scribing depth, on the characteristics of the resulting divided solar cells. When the scribing depth was greater than $100{\mu}m$, the solar cells were well separated. In addition, the desired scribing depths were reached in fewer scans when the laser spot overlap was 100%. The efficiency of the divided cells decreased due to the high series resistance at scribing depths of less than $100{\mu}m$. However, at scribing depths of approximately $100{\mu}m$, the series resistance was low and efficiency reduction was minimized.

• New & Renewable Energy
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• v.4 no.2
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• pp.68-73
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• 2008

It is very important that constitution of good hetero-junction interface with a high quality amorphous silicon thin films on very cleaned c-Si wafer for making high efficiency hetero-junction solar cells. For achieving the high efficiency solar cells, the inspection and management of c-Si wafer surface conditions are essential subjects. In this experiment, we analyzed the c-Si wafer surface very sensitively using Spectroscopic Ellipsometer for < ${\varepsilon}2$ > and u-PCD for effective carrier life time, so we accomplished < ${\varepsilon}2$ > value 43.02 at 4.25eV by optimizing the cleaning process which is representative of c-Si wafer surface conditions very well. We carried out that the deposition of high quality hydrogenated silicon amorphous thin films by RF-PECVD systems having high density and low crystallinity which are results of effective medium approximation modeling and fitting using spectroscopic ellipsometer. We reached the cell efficiency 12.67% and 14.30% on flat and textured CZ c-Si wafer each under AM1.5G irradiation, adopting the optimized cleaning and deposition conditions that we made. As a result, we confirmed that spectroscopic ellipsometry is very useful analyzing methode for hetero-junction solar cells which need to very thin and high quality multi layer structure.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.24 no.3
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• pp.240-244
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• 2011

The high cost of crystalline silicon solar cells has been considered as one of the major obstacles to their terrestrial applications. Spin on doping (SOD) is presented as a useful process for the manufacturing of low cost solar cells. Phosphorus (P509) was used as an n-type emitters of solar cells. N-type emitters were formed on p-type EFG ribbon Si wafers by using a SOD at different spin speed (1,000~4,000 rpm), diffusion temperatures ($800^{\circ}C{\sim}950^{\circ}C$), and diffusion time (5~30 min) in $N_2+O_2$ atmosphere. With optimum condition, we were able to achieve cell efficiency of 14.1%.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.18 no.5
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• pp.195-199
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• 2008

Production of the silicon feedstock for the semiconductor industry cannot meet the requirement for the solar cell industry because the production volume is too small and production cost is too high. This situation stimulates the solar cell industry to try the lower grade silicon feedstock like UMG (Upgraded Metallurgical Grade) silicon of 5$\sim$6 N in purity. However, this material contains around 1 ppma of dopant atoms like boron or phosphorous. Calculation of the composition profile of these impurities using segregation coefficient during crystal growth makes us expect the change of the type from p to n : boron rich area in the early solidified part and phosphorous rich area in the later solidified part of the silicon ingot. It was expected that the change of the growth speed during the silicon crystal growth is effective in controlling the amount of the metal impurities but not effective in reducing the amount of dopants.