• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07a
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• pp.318-321
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• 2002

This paper presents a proper condition to achieve high conversion efficiency using PC1D simulator on sri-crystalline Si solar cells. Various efficiency influencing parameters such as rear surface recombination velocity and minority carrier diffusion length in the base region, front surface recombination velocity, junction depth and doping concentration in the Emitter layer, BSF thickness and doping concentration were investigated. Optimized cell parameters were given as rear surface recombination of 1000 cm/s, minority carrier diffusion length in the base region 200 $\mu\textrm{m}$, front surface recombination velocity 100 cm/s, sheet resistivity of emitter layer 100 Ω/$\square$, BSF thickness 5 $\mu\textrm{m}$, doping concentration 5${\times}$10$\^$19/ cm$\^$-3/. Among the investigated variables, we learn that a diffusion length of base layer acts as a key factor to achieve conversion efficiency higher than 19 %.

• Solar Energy
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• v.5 no.2
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• pp.54-59
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• 1985

Due to the grainboundary recombination and the poor diffusion length, the polycrystalline cell efficiency is lower than the singlecrystalline cell. In order to define the effect of grains and grain-boundaries, 2 - dimensional differential diffusion equations of minority carrier are modelled. To solve them, two theoretical formulas are derived, which can be evaluated the grainboundary recombination velocity and the grain diffusion length. Also computer-aided numerical analysis is given.

• 한국신재생에너지학회:학술대회논문집
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• 2010.11a
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• pp.50.1-50.1
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• 2010

결정질 실리콘 태양전지의 원가에서 Wafer는 60~70%의 매우 높은 비중을 차지하고 있다. 많은 연구들이 원가 절감을 위하여 Wafer의 두께를 감소시키는 것에 집중하고 있다. 그러나 Wafer 두께의 감소는 태양전지의 효율 감소와 공정 진행 중에 파손율이 상승하는 등의 문제가 발생한다. 이에 본 논문에서는 결정질 태양전지 구조 중에서 24.7% 이상의 최고 변환 효율을 갖는 PERL(Passivated Emitter, Rear Locally diffuse) 구조를 대상으로 wafer 두께 감소에 따른 변환 효율 감소의 원인과 해결 방안을 제시하고자 한다. Simulation으로 확인한 결과 370 um 두께의 wafer에서 24.2 %의 효율은 50 um 두께의 wafer에서는 20.8 %로 감소함을 확인할 수 있었다. 얇아진 wafer에서 감소한 효율을 개선하기 위하여 후면 recombination velocity, 후면 fixed charge density, 후면 산화막 두께 등을 다양화하여, 각각의 경우에 대한 cell의 효율 변화를 살펴보았다. 그 결과 후면 recombination velocity, 후면 fixed charge density, 후면 산화막 두께를 최적화 하여, 각각 2.8 %p, 1.5 %p, 2.8 %p의 효율 개선 효과를 얻었다. 위 세 가지 효과를 동시에 적용하면 50 um wafer에서 370 um wafer 효율의 결과와 근접한 24.2 %의 효율을 얻을 수 있었다. 향후에는 위의 결과를 바탕으로 실제 실험을 통하여 확인할 계획이다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.11a
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• pp.257-257
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• 2009

This paper explores a control of recombination velocity for optimization the crystalline solar cell. Using PC1D simulator, the efficiency of crystalline solar cell was measured to be about 17%. The results show that the lower the front recombination velocity is, the more efficiency of crystalline solar cell improves. The work which presented here has profound implications for studies of crystalline solar cell and someday may help solve the problem of optimization for the crystalline solar cells.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.11a
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• pp.553-556
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• 1999

This paper presents a proper condition to achieve above 19 % conversion efficiency using PC1D simulator. Cast poly-Si wafers with resistivity of 1 $\Omega$-cm and thickness of 250 ${\mu}{\textrm}{m}$ were used as a starting material. Various efficiency influencing parameters such as rear surface recombination velocity and minority carrier diffusion length in the base region, front surface recombination velocity, junction depth and doping concentration in the Emitter layer, BSF thickness and doping concentration were investigated. Optimized cell parameters were given as rear surface recombination of 1000 cm/s, minority carrier diffusion length in the base region 200 ${\mu}{\textrm}{m}$, front surface recombination velocity 100 cnt/s, sheet resistivity of emitter layer 100 $\Omega$/$\square$, BSF thickness 5 ${\mu}{\textrm}{m}$, doping concentration 5$\times$10$^{19}$ cm$^3$ . Among the investigated variables, we learn that a diffusion length of base layer acts as a key factor to achieve conversion efficiency higher than 19 %. Further details of simulation parameters and their effects to cell characteristics are discussed in this paper.

• 전기의세계
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• v.28 no.4
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• pp.53-63
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• 1979

Interface recombination velocity in $Al_{x}$G $a_{1-x}$ As-GaAs and $Al_{0.85}$, G $a_{0.15}$ As-GaA $s_{1-y}$S $b_{y}$ heterojunction systems is studied as a function of lattice mismatch. The results are applied to the design of highly efficient III-V heterojunction solar cells. A horizontal liquid-phase epitaxial growth system was used to prepare p-p-p and p-p-n $Al_{x}$G $a_{1-x}$ As-GaA $s_{1-y}$S $b_{y}$-A $l_{x}$G $a_{1-x}$ As double heterojunction test samples with specified values of x and y. Samples were grown at each composition, with different GaAs and GaAs Sb layer thicknesses. A method was developed to obtain the lattice mismatch and lattice constants in mixed single crystals grown on (100) and (111)B oriented GaAs substrates. In the AlGaAs system, elastic lattice deformation with effective Poisson ratios .mu.$_{eff}$ (100=0.312 and .mu.$_{eff}$ (111B) =0.190 was observed. The lattice constant $a_{0}$ (A $l_{x}$G $a_{1-x}$ As)=5.6532+0.0084x.angs. was obtained at 300K which is in good Agreement with Vegard's law. In the GaAsSb system, although elastic lattice deformation was observed in (111) B-oriented crystals, misfit dislocations reduced the Poisson ratio to zero in (100)-oriented samples. When $a_{0}$ (GaSb)=6.0959 .angs. was assumed at 300K, both (100) and (111)B oriented GaAsSb layers deviated only slightly from Vegard's law. Both (100) and (111)B zero-mismatch $Al_{0.85}$ G $a_{0.15}$As-GaA $s_{1-y}$S $b_{y}$ layers were grown from melts with a weight ratio of $W_{sb}$ / $W_{Ga}$ =0.13 and a growth temperature of 840 to 820 .deg.C. The corresponding Sb compositions were y=0.015 and 0.024 on (100) and (111)B orientations, respectively. This occurs because of a fortuitous in the Sb distribution coefficient with orientation. Interface recombination velocity was estimated from the dependence of the effective minority carrier lifetime on double-heterojunction spacing, using either optical phase-shift or electroluminescence timedecay techniques. The recombination velocity at a (100) interface was reduced from (2 to 3)*10$^{4}$ for y=0 to (6 to 7)*10$^{3}$ cm/sec for lattice-matched $Al_{0.85}$G $a_{0.15}$As-GaA $s_{0.985}$S $b_{0.015}$ Although this reduction is slightly less than that expected from the exponential relationship between interface recombination velocity and lattice mismatch as found in the AlGaAs-GaAs system, solar cells constructed from such a combination of materials should have an excellent spectral response to photons with energies over the full range from 1.4 to 2.6 eV. Similar measurements on a (111) B oriented lattice-matched heterojunction produced some-what larger interface recombination velocities.ities.ities.s.

• 한국신재생에너지학회:학술대회논문집
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• 2010.11a
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• pp.43.1-43.1
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• 2010

In the crystalline silicon solar cells, the full area aluminum_back surface field(BSF) is routinely achieved through the screen-printing of aluminum paste and rapid firing. It is widely used in the industrial solar cell because of the simple and cost-effective process to suppress the overall recombination at the back surface. However, it still has limitations such as the relatively higher recombination rate and the low-to-moderate reflectance. In addition, it is difficult to apply it to thinner substrate due to wafer bowing. In the recent years, the dielectric back-passivated cell with local back contacts has been developed and implemented to overcome its disadvantages. Although it is successful to gain a lower value of surface recombination velocity(SRV), the series resistance($R_{series}$) becomes even more important than the conventional solar cell. That is, it is a trade off relationship between the SRV and the $R_{series}$ as a function of the contact size, the contact spacing and the geometry of the opening. Therefore it is essential to find the best compromise between them for the high efficiency solar cell. We have investigated the optimal design for the local back contact by using PC1D simulation.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2011.05a
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• pp.702-705
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• 2011

Poly-Si wafers with resistivity of 1 [${\Omega}$-cm[ and thickness of 50 [${\mu}m$] were used as a starting material. Various efficiency influencing parameters such as rear surface recombination velocity and minority carrier diffusion length in the base region, front surface recombination velocity, junction depth and doping concentration in the Emitter layer, BSF thickness and doping concentration were investigated. Optimized cell parameters were given as rear surface recombination of 1000 [cm/sec], minority carrier diffusion length in the base region 50 [${\mu}m$], front surface recombination velocity 100 [cm/sec], sheet resistivity of emitter layer 100 [${\Omega}/{\Box}$], BSF thickness 0.5 [${\mu}m$], doping concentration $5{\times}10^{19}\;cm^{-3}$. Among the investigated variables, we learn that a diffusion length of base layer acts as a key factor to achieve conversion efficiency higher than 19.8 %. Further details of simulation parameters and their effects to cell characteristics are discussed in this paper.

• Transactions on Electrical and Electronic Materials
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• v.6 no.6
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• pp.280-283
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• 2005

The moving photocarrier grating (MPG) technique for the determination of the carrier mobilities and the recombination lifetime of $\alpha$-Se:As films has been studied. The electron and hole drift mobility and the recombination lifetime of $\alpha$-Se films with arsenic (As) additions have been obtained from measurement of the short circuit current density $j_{sc}$ as a function of grating velocity and spatial period. The hole mobility decreases due to defect density of hole traps when x exceeds 0.003, whereas the hole mobility increases for the case of low As addition (x$\le$0.003). We have found an increase in hole drift mobility and recombination lifetime, especially when As with (x = 0.003) is added into the $\alpha$-Se film.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.53 no.4
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• pp.187-191
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• 2004

In this work, we used the PCID simulator for simulation of solar cell and examined the effect of front-back surface recombination velocity, minority carrier diffusion length, junction depth and emitter sheet-resistance. As the effect of base thickness, the efficiency decreased by the increase in series resistance with the increase of the thickness and found decrease in efficiency by decrease of the current as the effect of the recombination. Also, as the effect of base resistivity, the efficiency increased somewhat with the decrease in resistivity, but when the resistivity exceeded certain value, the efficiency decreased as a increase in the recombination ratio. The optimum efficiency was obtained at the resistivity 0.5 $\Omega$-cm, and thickness $100\mu\textrm{m}$. We have successfully achieved 10.8% and 13.7% efficiency large area($103mm{\times}103mm$) mono-crystalline silicon solar cells without and with PECVD silicon nitride antireflection coating.