• Current Photovoltaic Research
• /
• 제7권3호
• /
• pp.76-84
• /
• 2019

Silicon heterojunction solar cells (SHJ) have dominated the photovoltaic market up till now but their conversion performance is practically limited to around 26% compared with the theoretical efficiency limit of 29.4%. A silicon based multi-junction devices are expected to overcome this limitation. In this report, we briefly review the state-of-art characteristic of wide-gap materials which has played a role as top sub-cells in silicon based multi-junction solar cells. In addition, we indicate significantly practical challenges and key issues of these multi-junction combination. Finally, we focus to some characteristics of III-V/c-Si tandem configuration which are reaching highly record performance in multi-junction silicon solar cells.

• 세라미스트
• /
• 제22권2호
• /
• pp.146-169
• /
• 2019

To overcome the theoretical efficiency of single-junction solar cells (> 30 %), tandem solar cells (or multi-junction solar cells) is considered as a strong nominee because of their excellent light utilization. Organic-inorganic halide perovskite has been regarded as a promising candidate material for next-generation tandem solar cell due to not only their excellent optoelectronic properties but also their bandgap-tune-ability and low-temperature process-possibility. As a result, they have been adopted either as a wide-bandgap top cell combined with narrow-bandgap silicon or CuIn_xGa_(1-x)Se₂ bottom cells or for all-perovskite tandem solar cells using narrow- and wide-bandgap perovskites. To successfully transition perovskite materials from for single junction to tandem, substantial efforts need to focus on fabricating the high quality wide- and narrow-bandgap perovskite materials and semi-transparent electrode/recombination layer. In this paper, we present an overview of the current research and our outlook regarding perovskite-based tandem solar technology. Several key challenges discussed are: 1) a wide-bandgap perovskite for top-cell in multi-junction tandem solar cells; 2) a narrow-bandgap perovskite for bottom-cell in all-perovskite tandem solar cells, and 3) suitable semi-transparent conducting layer for efficient electrode or recombination layer in tandem solar cells.

• 조명전기설비학회논문지
• /
• 제25권12호
• /
• pp.34-41
• /
• 2011

In order to understand the thermal performance of each LED chips in multi-chip LED package, a quantitative parametric analysis of the temperature evolution was investigated by thermal transient analysis. TSP (Temperature Sensitive Parameter) value was measured and the junction temperature was predicted. Thermal resistance between the p-n junction and the ambient was obtained from the structure function with the junction temperature evolution during the cooling period of LED. The results showed that, the thermal resistance of the each LED chips in 4 chip-LED package was higher than that of single chip- LED package.

• 센서학회지
• /
• 제4권2호
• /
• pp.3-6
• /
• 1995

항온 유지 장치의 온도구배를 측정하기 위한 다중 접점을 갖는 K형 열전대를 제작하였다. 이 온도계를 사용하여 $800^{\circ}C$로 유지되고 있는 전기로의 온도구배를 측정하였으며, 교정용 기준기급의 S형 열전대와 비교한 결과 K형 열전대의 허용오차 범위 내에서 일치하였다. 더 정확한 온도구배 측정을 위해서는 귀금속 열전대를 사용하는 것이 바람직하다는 것을 제안하였다.

• 진공이야기
• /
• 제1권4호
• /
• pp.4-9
• /
• 2014

About 170 years has been passed since the concept of photovoltaic has been suggested by French physicist Alexandre-Edmond Becquerel. Now the highest efficiency of solar cell has reached up to 44% by III-V multi-junction solar cells with concentrator. Those multi-junction solar cells are suitable as energy source for spaceships. On the other hand, the cell efficiency of solar cell for electric power generation as energy source for Earth has is going to be saturated although commercial solar cell efficiency is around 20%. In the part 1 of this article, the history of III-V multi-junction solar cells which have been adapted for spaceships is explained and in the part 2, new approach for the improvement of cell efficiency is suggested as the energy source for Earth.

• 전기전자학회논문지
• /
• 제25권2호
• /
• pp.356-361
• /
• 2021

파워 소자의 트레이드오프 현상을 최소화하기 위해 제시된 구조가 Super Junction 구조이다. Super Junction은 기존의 많이 사용하던 기본 구조 대비 1/5 정도의 낮은 온 저항(Ron) 특성을 가질 수 있다. Super Junction 구조의 공정 방법으로 Multi-Epi 공정과 Deep-Trench 공정 방법이 있다. Deep-Trench 공정은 실리콘 기판 상면에 깊은 트렌치 공정을 통하여 그안에 불순물이 도핑 되어 있는 폴리실리콘을 매립하여 P-Pillar를 형성 시키는 공정 방법이라 매립하는 과정에서 결함이 형성되기 쉬워서 비교적 어려운 제조 방법으로 알려져 있다. 하지만 비교적 Deep-Trench 공정으로 만들어진 구조가 낮은 온저항과 높은 항복 전압을 형성하여 좋은 효율을 보인다. 본 논문에서는 공정상의 새로운 방법을 제시하고, Charge Balance 이론을 접목시킨 구조를 설계하였다.

• Current Photovoltaic Research
• /
• 제8권3호
• /
• pp.94-101
• /
• 2020

This study was trying to focus on achieving high efficiency of multi junction solar cell with thin film silicon solar cells. The proposed thin film Si-Ge/c-Si tandem junction solar cell concept with a combination of low-cost thin-film silicon solar cell technology and high-efficiency c-Si cells in a monolithically stacked configuration. The tandem junction solar cells using amorphous silicon germanium (a-SiGe:H) as an absorption layer of upper sub-cell were simulated through ASA (Advanced Semiconductor Analysis) simulator for acquiring the optimum structure. Graded Ge composition - effect of E_g profiling and inserted buffer layer between absorption layer and doped layer showed the improved current density (J_sc) and conversion efficiency (η). 13.11% conversion efficiency of the tandem junction solar cell was observed, which is a result of showing the possibility of thin film Si-Ge/c-Si tandem junction solar cell.

• 한국진공학회:학술대회논문집
• /
• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
• /
• pp.322.1-322.1
• /
• 2014

Many research groups have studied tandem or multi-junction cells to overcome this low efficiency and degradation. In multi-junction cells, band-gap engineering of each absorb layer is needed to absorb the light at various wavelengths efficiently. Various absorption layers can be formed using multi-junctions, such as hydrogenated amorphous silicon carbide (a-SiC:H), amorphous silicon germanium (a-SiGe:H) and microcrystalline silicon (${\mu}c$-Si:H), etc. Among them, ${\mu}c$-Si:H is the bottom absorber material because it has a low band-gap and does not exhibit light-induced degradation like amorphous silicon. Nevertheless, ${\mu}c$-Si:H requires a much thicker material (>2 mm) to absorb sufficient light due to its smaller light absorption coefficient, highlighting the need for a high growth rate for productivity. ${\mu}c$-SiGe:H has a much higher absorption coefficient than ${\mu}c$-Si:H at the low energy wavelength, meaning that the thickness of the absorption layer can be decreased to less than half that of ${\mu}c$-Si:H. ${\mu}c$-SiGe:H films were prepared using 40 MHz very high frequency PECVD method at 1 Torr. SiH4 and GeH4 were used as a reactive gas and H2 was used as a dilution gas. In this study, the ${\mu}c$-SiGe:H layer for triple solar cells applications was performed to optimize the film properties.

• Journal of the Korean Society for Industrial and Applied Mathematics
• /
• 제21권2호
• /
• pp.63-73
• /
• 2017

Segmenting the image into multiple regions is at the core of image processing. Many segmentation formulations of an images with multiple regions have been suggested over the years. We consider segmentation algorithm based on the multi-phase level set method in this work. Proposed method gives the best result upon other methods found in the references. Moreover it can segment images with intensity inhomogeneity and have multiple junction. We extend our method (GLIF) in [T. Dultuya, and M. Kang, Segmentation with shape prior using global and local image fitting energy, J.KSIAM Vol.18, No.3, 225-244, 2014.] using a multiphase level set formulation to segment images with multiple regions and junction. We test our method on different images and compare the method to other existing methods.

• 한국전기전자재료학회논문지
• /
• 제33권3호
• /
• pp.173-176
• /
• 2020

This study focuses on a pillar in which is implanted a P-type maneuver under a P base. This structure is called a super junction structure. By inserting the pillar, the electric field concentrated on the P base is shared by the pillar, so the columns can be dispersed while maintaining a high breakdown voltage. Ten pillars were generated during the multi epitaxial process. The interval between pillars is varied to optimize the electric field to be concentrated on the pillar at a threshold voltage of 6 V, a yield voltage of 4,500 V, and an on-state voltage drop of 3.8 V. The density of the filler gradually decreased when the interval was extended by implanting a filler with the same density. The results confirmed that the size of the depletion layer between the filler and the N-epitaxy layer was reduced, and the current flowing along the N-epitaxy layer was increased. As the interval between the fillers decreased, the cost of the epitaxial process also decreased. However, it is possible to confirm the trade-off relationship that deteriorated the electrical characteristics and efficiency.