• Current Photovoltaic Research
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• v.3 no.4
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• pp.126-129
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• 2015

Over the last two decades, quantum dot (QD) solar cells have attracted much attention due to the unique properties of QDs, including band gap tunability, slow hot electron cooling, and multiple exiton generation effect. However, most of the QDs employed in photovoltaic devices contain toxic heavy-metals such as cadmium or lead, which may limit the commercial application. Therefore, recently, heavy-metal-free QDs such as Cu-In-S or Cu-In-Se have been developed for application in solar cells. Here, we review the research trends in heavy-metal-free QD solar cells, mainly focusing on Cu-In-Se QD-sensitized solar cells (QDSC).

• Current Photovoltaic Research
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• v.1 no.1
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• pp.11-16
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• 2013

The current solar cell industry is experiencing a temporary plateau due to a sluggish economy and oversupply. It is expected that the solar industry can see similar growth to that of the recent past by overcoming the current situation, as there is growing demand globally for solar energy. The current situation led to restructuring of the world's solar industry, and domestic firms will need to have competitiveness through strategic approaches and proprietary technology to survive in the global solar market. Crystalline and amorphous silicon based solar cells have led the solar industry and occupied half or more of the market thus far. They will do so in the future PV market as well by playing a pivotal role in the solar industry. In this paper, the current status and prospects of silicon based solar cells, from materials to comprehensive and high efficiency technology that can emerge in the future, are discussed.

• Journal of the Korean Solar Energy Society
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• v.38 no.1
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• pp.37-44
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• 2018

Solar panels are modules made up of many cells, like the N-type monosilicon, P-type monosilicon, P-type multisilicon, amorphous thin-film silicon, and CIGS solar cells. An efficient photovoltaic (PV) power is important to use to determine what kind of cell types are used because residential solar systems receive attention. In this study, we used 3-type solar panels - such as N-type monosilicon, P-type monosilicon, and CIGS solar cells - to investigate what kind of solar panel on a house or building performs the best. PV systems were composed of 3-type solar panels on the roof with each ~1.8 kW nominal power. N-type monosilicon solar panel resulted in the best power generation when monitored. Capacity Utilization Factor (CUF) and Performance Ratio (PR) of the N-type Si solar panel were 14.6% and 75% respectively. In comparison, N-type monosilicon and CIGS solar panels showed higher performance in power generation than P-type monosilicon solar power with increasing solar irradiance.

• Current Photovoltaic Research
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• v.4 no.3
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• pp.98-107
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• 2016

Third-generation photovoltaics are of low cost based on solution processes and are targeting a high efficiency. To meet the commercial demand, however, significant improvements of both efficiency and stability are required. In this sense, interfacial engineering can be useful key to solve these issues because trap sites and interfacial energy barrier and/or chemical instability at organic/organic and organic/inorganic interfaces are critical factors of efficiency and stability degradation. Here, we thoroughly review the interfacial engineering strategies applicable to three representative third-generation photovoltaics - organic, perovskite, colloidal quantum dot solar cell devices.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.59 no.3
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• pp.293-297
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• 2010

Next generation concentrating photovoltaic technologies could have a large-scale impact on world electricity production once they will become economically attractive and grid parity will be reached. Multi-junction solar cells will be characterised by a high value of the cell economical performance index if the cells were able to operate at high concentration level. Concentrating the sunlight by optical devices like lenses or mirrors reduces the area of expensive solar cells or modules, and, moreover, increases their efficiency. Accurate and reliable tracking is an important issue to maintain high the CPV system output power. Further, for high concentration CPV systems, the actual tracker cost is about 20% of the total CPV system cost. In this paper high-concentration is defined as systems using concentration ratios well above 100 times the one sun intensity and trackerlss CPV system studied. Using sphericalness lens and parallel MJ cell connection method were suggested and achieved experiment on a clear day in summer. Development of these high performance multi-junction CPV module promises to accelerate growth in photovoltaic power generation.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.36 no.5
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• pp.442-453
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• 2023

Tandem or multijunction solar cells (MJSCs) can convert sunlight into electricity with higher efficiency (η) than single junction solar cells (SJSCs) by dividing the solar irradiance over sub-cells having distinct bandgaps. The efficiencies of various common SJSC materials are close to the edge of their theoretical efficiency and hence there is a tremendous growing interest in utilizing the tandem/multijunction technique. Recently, III-V materials integration on a silicon substrate has been broadly investigated in the development of III-V on Si tandem solar cells. Numerous growth techniques such as heteroepitaxial growth, wafer bonding, and mechanical stacking are crucial for better understanding of high-quality III-V epitaxial layers on Si. As the choice of growth method and substrate selection can significantly impact the quality and performance of the resulting tandem cell and the terminal configuration exhibit a vital role in the overall proficiency. Parallel and Series-connected configurations have been studied, each with its advantage and disadvantages depending on the application and cell configuration. The optimization of both growth mechanisms and terminal configurations is necessary to further improve efficiency and lessen the cost of III-V on Si tandem solar cells. In this review article, we present an overview of the growth mechanisms and terminal configurations with the areas of research that are crucial for the commercialization of III-V on Si tandem solar cells.

• Applied Science and Convergence Technology
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• v.23 no.5
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• pp.221-239
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• 2014

The global demand for energy has been increasing since past decades. Various technologies have been working to find a suitable alternative for the generation of sustainable energy. Photovoltaic technologies for solar energy conversion represent one of the significant routes for the green and renewable energy production. Despite of remarkable improvement in solar cell technologies, the generation of power is still suffering with lower energy conversion efficiency, high production cost, etc. The major problem in improving the PV efficiency is spectral mismatch between the incident solar spectrum and bandgap of a semiconductor material used in solar cell. Luminescent materials such as rare-earth doped phosphor materials having the quantum efficiency higher than unity can be helpful for photovoltaic applications. Quantum cutting phosphors are the most suitable candidates for the generation of two or more low-energy photons for the absorption of every incident high-energy photons. The phosphors which are capable of converting UV photon to visible and near-IR (NIR) photon are studied primarily for photovoltaic applications. In this review, we will survey various near IR quantum cutting phosphors with respective to their synthesis method, energy transfer mechanism, nature of activator, sensitizer and dopant materials incorporation and energy conversion efficiency considering their applications in photovoltaics.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.04a
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• pp.31-34
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• 2004

During the last 20 years organic semiconductors have attracted considerable attention due to their interesting physical properties followed by various technological applications in the area of electronics and opto-electronics. It has been a long time since organic solar cells were expected as a low-cost energy-conversion device. Although practical use of them has not been achieved, technological progress continues. Morphology of the materials, organic/inorganic interface, metal cathodes, molecular packing and structural properties of the donor and acceptor layers are essential for photovoltaic response. We have fabricated solar cell devices based on zinc-phthalocyanine(ZnPc) as donor(D) and fullerine$(C_{60})$ as electron acceptor(A) with doped charge transport layers, $Alq_3$ as an electron transport or injection layer. We observed the photovoltaic characteristics of the solar celt devices using the Xe lamp as a light source.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.1108-1109
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• 2008

To survive in outdoor environments, photovoltaic modules rely on packaging materials to provide requisite durability. We analyzed the properties of encapsulant materials that are important for photovoltaic module packaging. Recently, the thickness of solar cell gets thinner to reduce the quantity of silicon. And the reduced thickness make it easy to be broken while PV module fabrication process. Solar cell's micro cracks are increasing the breakage risk over the whole value chain from the wafer to the finished module, because the wafer or cell is exposed to tensile stress during handling and processing. This phenomenon might make PV module's maximum power and durability down. So, when using thin solar cell for PV module fabrication, it is needed to optimize the material and fabrication condition which is quite different from normal thick solar cell process. Normally, gel-content of EVA sheet should be higher than 80% so PV module has long term durability. But high gel-content characteristic might cause micro-crack on solar cell. In this experiment, we fabricated several specimen by varying curing temperature and time condition. And from the gel-content measurement, we figure the best fabrication condition. Also we examine the crack generation phenomenon during experiment.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.54 no.4
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• pp.188-194
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• 2005

There are many factors that affect on the system output of Photovoltaic(PV) power generation; the variation of solar radiation, temperature, energy conversion efficiency of solar cell etc. This paper suggests a methodology for calculation of PV generation output using the probability distribution function of irradiance, PV array efficiency and revision factors of solar cell conversion efficiency. Long-term irradiance data recorded every hour of the day for 11 years were used. For goodness-fit test, several distribution (unctions are tested by Kolmogorov-Smirnov(K-S) method. The calculated generation output with or without revision factors of conversion efficiency is compared with that of CMS (Centered Monitoring System), which can monitor PV generation output of each PV generation site.