• Bulletin of the Korean Chemical Society
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• 제32권8호
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• pp.2743-2750
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• 2011

Lanthanide(III)-cored complex as a wavelength conversion material has been successfully designed and synthesized for highly efficient dye-sensitized solar cells, for the first time, since light with a short wavelength has not been effectively used for generating electric power owing to the limited absorption of these DSSCs in the UV region. A black dye (BD) was chosen and used as a sensitizer, because BD has a relatively weak light absorption at shorter wavelengths. The overall conversion efficiency of the BD/WCM device was remarkably increased, even with the relatively small amount of WCM added to the device. The enhancement in $V_{oc}$ by WCM, like DCA, could be correlated with the suppression of electron recombination between the injected electrons and $I_3{^-}$ ions. Furthermore, the short-circuit current density was significantly increased by WCM with a strong UV light-harvesting effect. The energy transfer from the Eu(III)-cored complex to the $TiO_2$ film occurred via the dye, so the number of electrons injected into the $TiO_2$ surface increased, i.e., the short-circuit current density was increased. As a result, BD/WCM-sensitized solar cells exhibit superior device performance with the enhanced conversion efficiency by a factor of 1.22 under AM 1.5 sunlight: The photovoltaic performance of the BD/WCM-based DSSC exhibited remarkably high values, $J_{sc}$ of 17.72 mA/$cm^2$, $V_{oc}$ of 720 mV, and a conversion efficiency of 9.28% at 100 mW $cm^{-2}$, compared to a standard DSSC with $J_{sc}$ of 15.53 mA/$cm^2$, $V_{oc}$ of 689 mV, and a conversion efficiency of 7.58% at 100 mW $cm^{-2}$. Therefore, the Eu(III)-cored complex is a promising candidate as a new wavelength conversion coadsorbent for highly efficient dye-sensitized solar cells to improve UV light harvesting through energy transfer processes. The abstract should be a single paragraph which summaries the content of the article.

• 한국태양에너지학회 논문집
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• 제32권2호
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• pp.1-10
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• 2012

A photovoltaic/thermal (PVT)solar system is the solar technology that allows for simultaneous conversion of solar energy into both electricity and heat. This paper compared the performance of PVT system with a conventional PV module and solar collector and analyzed electrical and thermal efficiency of PVT system in terms of solar irradiance and inlet temperature of the working fluid. Based on the experimental data, thermal and electrical efficiencies of he glazed PVT system were57.9% and14.27% under zero reduced temperature condition which were lower by 13.6% than the solar thermal absorber plate and by 0.08% than the PV module respectively. For the unglazed PVT system it had lower thermal efficiency than the solar thermal absorber plate but higher electrical performance than the PV module due to the cooling effect by the working fluid. However, total efficiency of the glazed PVT system was72.2% which was higher than combined efficiencies of the solar collector and PV module. Besides, total efficiency of the PVT system would be much higher if calculated based on unit area.

• 한국전기전자재료학회논문지
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• 제30권5호
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• pp.325-330
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• 2017

We fabricated 1-D and 2-D diffraction gratings of SiOx anti-reflection (AR) film grown on a quartz substrate and integrated them into a c-Si photovoltaic (PV) submodule. The light-trapping effect of the resulting submodules was studied in terms of the oblique optical incident angle, ${\theta}_i$. As the ${\theta}_i$ increased, solar conversion efficiency, ${\eta}$, was improved as expected by the increased optical transmission caused by the grating. For ${\theta}_i{\leq}30^{\circ}$, the relative solar conversion efficiency, ${\Delta}{\eta}$, of a 1-D SiOx (t=300 nm) grating, compared to that of a flat SiOx AR-coated integrated PV submodule, was improved very little, with a small variation of within 2%, but increased markedly for ${\theta}_i{\geq}40^{\circ}$. We observed a change of ${\Delta}{\eta}$ as large as 10.7% and 9.5% for the SiOx grating of period t=800 nm and 1200 nm, respectively. For a 2-D SiOx (t=300 nm) grating integrated PV submodule, however, the optical trapping behavior was similar in terms of ${\theta}_i$ but its variation was small, within ${\pm}1.0%$.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2015년도 제49회 하계 정기학술대회 초록집
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• pp.243.1-243.1
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• 2015

To replace the based on silicon solar cells, the third generation solar cells, Dye-sensitized solar cells (DSSCs), is low fabrication than silicon solar cells, environmentally friendly and can be applied to various field. For this reason, the DSSCs have been continuously researched. But DSSCs have one drawback that is the low power conversion efficiency (PCE) than silicon solar cells. To solve the problem, we used the backr-eflector the Al foil that can be easily obtained from the surrounding in order to improve the efficiency of the DSSCs. Easily detachable Al foil back-reflector increases the photocurrent by enhancing the harvesting light because the discarded light is reused. It also leads to enhance the power conversion efficiency (PCE). In addition, we compared with the efficiency of the DSSCs that is applied and does not be applied with back-reflector according to the thickness of the TiO2 photoelectrode. When the back-reflector is applied to DSSCs, the photocurrent is increased. It leads to affect the efficiency. We used to solar simulator and Electrochemical Impedance Spectroscopy (EIS) to confirm the PCE and resistance. The DSSCs were also measured by External Quantum effect (EQE). At the same time, FE-SEM and XRD were used to confirm the thickness of layer and crystal structural of photoelectrode.

• 한국전기전자재료학회논문지
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• 제35권6호
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• pp.581-593
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• 2022

As energy depletion and environmental pollution problems are intensified, research has been conducted actively on alternative energy sources, an eco-friendly and continuous available energy conversion system. So has been organic solar cells whose efficiency is improved to 18.32%. The photoactive layer inside the solar cell is composed of a donor and a acceptor, and the combination of materials capable of effectively exchanging electrons greatly affects the efficiency of the organic solar cell. Accordingly, various researches have been conducted to improve the efficiency, and the maximum efficiency could be achieved by a solar cell with high carrier generation and low charge recombination characteristics through the introduction of a non-fullerene acceptor and material reconstruction. Organic solar cells are still difficult to commercialize due to their efficiency limitations and light stability, but if a photoactive layer consisting of a donor capable of efficiently absorbing long-wavelength light and an acceptor capable of forming an appropriate energy level is designed, the efficiency of the organic solar cell will reach 20%.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2009년도 하계학술대회 논문집
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• pp.243-244
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• 2009

The $TiO_2$ nanofiber doped $TiO_2$ electrode area applied to dye-sensitized solar cells(DSSCs). The mixtures of $TiO_2$ nanofiber to $TiO_2$ photoelectrode has larger surface area than $TiO_2$ photoelectrode. In this research added 2.5, 5 and 10wt% $TiO_2$ nanofibers and the optimum condition of 5 wt% $TiO_2$ nanofiber's high surface area contributing the improvement of short-circuit photocurrent. The open-circuit voltage was 0.7V and solar energy conversion efficiency was 5.4%.

• 전기학회논문지P
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• 제61권4호
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• pp.192-198
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• 2012

Switch losses directly affect the efficiency of power conversion systems and those have big differences according to the power consumed by load systems and the structures of power conversion circuits. In this paper, analyses for switch losses in DC link converter are performed based on the circuit structures of the DC/DC converter in photovoltaic generation system whose output power is varied according to the amount of solar radiation, temperature and partial shade on the solar modules. Boost converter is adopted as a DC link converter topology of the photovoltaic generation system and the loss analyses for the switches used in the boost converters are performed according to the circuit structures. Analyses like the things performed in this paper will be a prerequisite to designing the photovoltaic generation system whose output power is changed according to the environmental variations.

• Bulletin of the Korean Chemical Society
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• 제28권11호
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• pp.1973-1979
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• 2007

Novel organic dyes, JK-34, JK-35 and JK-36 containing bis-dimethylfluorenyl amino coumarin unit are designed and synthesized. Nanocrystalline TiO2 dye-sensitized solar cells were fabricated using these dyes. Under standard global AM 1.5 solar condition, the JK-34 sensitized cell gave a short circuit photocurrent density of 10.05 mA cm?2, open circuit voltage of 0.65 V, and a fill factor of 0.68, corresponding to an overall conversion efficiency η of 4.54%. We found that the power conversion efficiency was shown to be quite sensitive to the structural modifications of bridging thiophene moiety.

• 태양에너지
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• 제6권2호
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• pp.70-75
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• 1986

The fabrication procedure and characteristics of $Ta_2O_5/Al/SiO_2/p-Si$ MIS solar cells forming a fine grating pattern of aluminum evaporated on to p-type silicon crystal are discribed. The proper temperature for oxide growing of these cells was found to be about $450^{\circ}C$ for 20 minutes with oxygen flow. The conversion efficiency increased about 3% after $750{\AA}$ thickness of tantalium silica film spin on anti-reflective coating. The best results showed that $V_{oc}=0.545V,\;J_{sc}=34mA$ and F.F = 0.65, which represent that the conversion efficiency is 12%.

• 반도체디스플레이기술학회지
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• 제17권1호
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• pp.40-44
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• 2018

In this paper, the efficiency of the solar system is lowered due to the partial shading such as the environmental factors of the solar panel. In order to solve this problem, a DC OPTIMIZER is proposed for a maximum power generation system of a photovoltaic panel. The proposed DC OPTIMIZER is composed of a buck structure that performs the maximum power point tracking (MPPT) control of each module of the solar panel, thus maximizing the efficiency. In order to verify the proposed DC Optimizer, the efficiency was measured by varying the irradiance using a solar simulator instead of the solar panel. As a result, it showed high efficiency characteristics as the maximum energy conversion efficiency was 99.3% at $800w/m^2$, $900w/m^2$, and the average efficiency was 99.06% excluding $100w/m^2$. The maximum efficiency of MPPT was 99.97% at $200w/m^2$, efficiency showed excellent performance.