• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.387.2-387.2
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• 2016

Glass texturing is a sufficient method for changing the surface morphology to enhance the light trapping. In this study, glass texturing was applied to the perovskite solar cell for improving the current density. Glass substrates (back-side glass of FTO coated glass substrate) were textured by randomly structure assisted wet etching process using diluted HF solution at a constant concentration of etchants (HF:H2O=1:1). Then, the light trapping properties of suitable films were controlled over a wide range by varying the etching time (1, 2, 3, 4 and 5 min.). The surface texturing changed the reflected light in an angle that it can be reflected by substrate glass surface. As a result, Current density and cell efficiency were affected by light trapping layer using glass texturing method in perovskite solar cells.

• Current Photovoltaic Research
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• v.2 no.3
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• pp.95-102
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• 2014

Light trapping techniques can change the propagation direction of incident light and keep the light longer in the absorption layers of solar cells to enhance the power conversion efficiency. In thin film silicon (Si) solar cells, the thickness of absorption layer is generally not enough to absorb entire available photons because of short carrier life time, and light induced degradation effect, which can be compensated by the light trapping techniques. These techniques have been adopted as textured transparent conduction oxide (TCO) layers randomly or periodically textured, intermediate reflection layers of tandem and triple junction, and glass substrates etched by various patterning methods. We reviewed the light trapping techniques for thin film Si solar cells and mainly focused on the commercially available techniques applicable to textured TCO on patterned glass substrates. We described the characterization methods representing the light trapping effects, texturing of TCO and showed the results of multi-scale textured TCO on etched glass substrates. These methods can be used tandem and triple thin film Si solar cells to enhance photo-current and power conversion efficiency of long term stability.

• Transactions on Electrical and Electronic Materials
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• v.17 no.5
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• pp.275-279
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• 2016

This is a brief review on light trapping in Si based thin film solar cells with textured surfaces and transparent conducting oxide front electrodes. The light trapping scheme appears to be essential in improving device efficiency over 10%. As light absorption in a thin film solar cells is not sufficient, light trapping becomes necessary to be effectively implemented with a textured surface. Surface texturing helps in the light trapping, and thereby raises short circuit current density and its efficiency. Such a scheme can be adapted to single junction as well as tandem solar cell, amorphous or micro-crystalline devices. A tandem cell is expected to have superior performance in comparison to a single junction cell and random surface textures appears to be preferable to a periodic structures.

• 한국신재생에너지학회:학술대회논문집
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• 2010.11a
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• pp.58.1-58.1
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• 2010

Stainless Steel의 유연한 기판을 사용하여 ZnO:Al/Ag의 후면전극에서 Ag 증착 실험조건 변화를 통해서 light trapping을 개선한 n-i-p 구조의 플렉서블 미세결정질 실리콘 박막 태양전지를 제작하였다. 실험 방법으로 마그네트론 스퍼터를 사용하여 Stainless Steel 기판 위에 ZnO:Al/Ag를 증착하여 후면전극으로 사용되는 back reflector를 제작하였으며 그 위에 미세결정질 실리콘 박막을 증착하였다. Back reflector에서 Ag 박막의 증착 온도가 증가할수록 표면결정 성장으로 roughness가 증가하여 반사도를 증가하였다. 또한, Ag 박막 증착 두께와 압력 변화에 따른 광학적 특성변화를 Atomic Force Microscope(AFM), Scanning Electron Microscopy(SEM),UV-visible-nIR spectrometry로 조사하여 최적의 조건을 찾았으며 개선된 back reflector의 특성이 n-i-p 구조의 플렉서블 미세결정질 실리콘 박막 태양전지에 적용하여 light trapping의 증가가 태양전지에서 광학적인 특성 변화 및 효율 향상에 영향을 주는지 Photo IV와 EQE(External Quantum Efficiency)를 통하여 조사하였다.

• Journal of Information Display
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• v.9 no.2
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• pp.14-17
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• 2008

A charge trapping host structure was developed to improve the light-emitting efficiency of green phosphorescent organic light-emitting diodes. N, N'-dicarbazolyl-3,5-benzene(mCP) and a spirobifluorene based triplet host(PHl) were co-deposited as hosts in the emitting layer and the device performance was examined according to the composition mCP and PH1. The results showed that the quantum efficiency could be improved by 30 % using a mixed host of mCP and PH1.

• Journal of the Semiconductor & Display Technology
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• v.18 no.3
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• pp.19-24
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• 2019

In this study, the Ag nano-dots structure was applied to the textured wafer surface to improve the light trapping effect of crystalline silicon solar cell. The Ag nano-dots structure was formed by the annealing of Ag thin film. Ag thin film deposition was performed using a thermal evaporator. The effect of light trapping was compared and analyzed through light reflectance measurements. The optimization process of the Ag nano-dots structure was made by varying the thickness of Ag thin film, the annealing temperature and time. The thickness of Ag thin films was in the range of 5 ~ 20 nm. The annealing temperature was in the range of 450~650℃ and the annealing time was in the range of 30 ~ 60 minutes. As a result, the light reflectance of 10 nm Ag thin film annealed at 650℃ for 30 minutes showed the lowest value of about 9.67%. This is a value that is about 3.37% lower than the light reflectance of the sample that has undergone only the texturing process. Finally, the change of the light reflectance by the HF treatment of the sample on which the Ag nano-dots structure was formed was investigated. The HF treatment time was in the range of 0 ~ 120 seconds. As a result, the light reflectance decreased by about 0.41% due to the HF treatment for 75 seconds.

• Current Photovoltaic Research
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• v.4 no.1
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• pp.1-7
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• 2016

Among the various types of solar cells, silicon based two terminal tandem solar cell is one of the most popular one. It is designed to split the absorption of incident AM1.5 solar radiation among two of its component cells, thereby widening the wavelength range of external quantum efficiency (EQE) spectra of the device, in comparison to that of a single junction solar cell. In order to improve the EQE spectra further and raise short circuit current density ($J_{sc}$) an optimization of the tradeoff between the top and bottom cell is needed. In an optimized cell structure, the $J_{sc}$ and hence efficiency of the device can further be enhanced with the help of light trapping scheme. This can be achieved by texturing front and back surface as well as a back reflector of the device. In this brief review we highlight the development of light trapping in the silicon based tandem solar cell.

• Journal of Electrochemical Science and Technology
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• v.7 no.3
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• pp.218-227
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• 2016

The light harvesting efficiency is counted as an important factor in the power conversion efficiency of DSSCs. There are two measures to improve this parameter, including enhancing the dye-loading capacity and increasing the light trapping in the photoanode structure. In this paper, these tasks are addressed by introducing a macro-porous silicon (PSi) substrate as photoanode. The effects of the novel photoanode structure on the DSSC performance have been investigated by using energy dispersive X-ray spectroscopy, photocurrent-voltage, UV-visible spectroscopy, reflectance spectroscopy, and electrochemical impedance spectroscopy measurements. The results indicated that bigger porosity percentage of the PSi structure improved the both anti-reflective/light-trapping and dye-loading capacity properties. PSi based DSSCs own higher power conversion efficiency due to its remarkable higher photocurrent, open circuit voltage, and fill factor. Percent porosity of 64%, PSi(III), resulted in nearly 50 percent increment in power conversion efficiency compared with conventional DSSC. This paper showed that PSi can be a good candidate for the improvement of light harvesting efficiency in DSSCs. Furthermore, this study can be considered a valuable reference for more investigations in the design of multifunctional devices which will profit from integrated on-chip solar power.

• Current Photovoltaic Research
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• v.4 no.3
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• pp.119-123
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• 2016

We discussed various cover glass substrates available for photovoltaic (PV) modules, and investigated the fabrication methods of light trapping structures for the efficiency enhancement of PV modules: wet and dry etching or laser and direct patternings. We also introduced the analysis of haze at etched glass surfaces as a function of wavelength and also presented a anti-reflection coating technology for PV module.

• Journal of the Optical Society of Korea
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• v.18 no.1
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• pp.9-14
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• 2014

We numerically investigate the effect of sunlight polarization on the absorption efficiency of V-shaped organic solar cells (VOSCs) using the finite element method (FEM). The spectral distribution of absorbance and the spatial distribution of power dissipation are calculated as a function of the folding angle for s-and p-polarized light. The absorption enhancement caused by the light-trapping effect was more pronounced for s-polarized light at folding angles smaller than $20^{\circ}$, where s-polarized light has a relatively larger reflectance than p-polarized light. On the other hand, the absorption efficiency for p-polarized light is relatively larger for folding angles larger than $20^{\circ}$, where the smaller reflectance at the interface of the VOSC is more important in obtaining high absorption efficiency.