臺灣博碩士論文加值系統

高效率III-V族化合物半導體多接面太陽電池主要藉由多個子電池分別吸收不同波段的太陽光譜，以輸出比單接面太陽電池要高的電壓以及較低的電流。由於將光譜分段吸收，此種多接面太陽電池對於太陽光譜變化之反應亦較單接面太陽電池敏感，所以當計算其轉換效率時，太陽光譜的變化應該要被列入考量。此論文所敘述者係以InGaP/InGaAs/Ge三接面太陽電池為例，利用太陽模擬器分別調整在短波長(200-900 nm)和長波長(>900 nm) 的光譜強度(70-100 mW/cm2)，並將所模擬的光譜與InGaP/InGaAs/Ge三接面太陽電池的光譜響應作積分，以判斷在太陽光譜產生變化的情況下是否影響到電流限制子電池的演變以及所導致的太陽電池轉換效率變化。
結果指出，於短波長部份的光譜強度由100至70 mW/cm2的降下範圍內，造成短路電流下降達58%，而於長波長光譜強度同樣的降下範圍內只造成短路電流35%的下降，特別是，短波長光譜強度的降下甚至導致限制子電池由中間子電池轉變為頂部子電池。另一方面，開路電壓與填充因子則不隨長短波長光譜強度的改變而明顯變化。綜合上述效應，長波長光譜強度下降導致太陽能電池的轉換效率衰退約8%；而短波長光譜強度下降更造成轉換效率高達38%的掉落。

The high efficiency of III-V compound semiconductor multi-junction solar cells is achieved mainly by absorbing different bands of solar spectrum with their corresponding subcells to afford a higher output voltage and a lower output current than single junction ones. The influence of variations in solar spectrum on multi-junction solar cells is more evident than single-junction ones due to the separation of absorption ranges of solar spectrum for the former. It is therefore important to consider the effects of spectral variations when the performance of high-efficiency multi-junction solar cells is evaluated. In this study, we modulated the intensity of incident spectrum by a solar simulator and integrated it with the spectral response data of InGaP/(In)GaAs/Ge triple-junction solar cell to examine the corresponding responses of solar cell. It is suggested that short circuit current decayed because of the reduction of solar spectrum, which therefore resulted in the drop of the conversion efficiency of triple junction solar cell. Besides, current limiting cell was changed from middle subcell to top subcell when the solar spectrum irradiance at the short wavelength side reduced.

Content
摘要
English abstract
致謝
Content
Figure captions
List of tables
Chapter 1 Introduction
1.1 Why we need photovoltaics
1.2 Classification of solar cells
1.3 III-V compound-based solar cell
Chapter 2 Theory Foundation of the Solar Cell
2.1 Solar spectrum
2.2 Basic principle of solar cells
2.3 The equivalent circuit of solar cell
2.4 Fundamental solar cell parameters
2.5 Spectral response
2.6 Optical device design
2.7 Temperature and irradiance effects
Chapter 3 The measurement systems
3.1 Current-voltage (I-V) of solar cells measurement
3.2 Quantum efficiency of solar cells measurement
Chapter 4 The Experiments
4.1 Introduction
4.2 Experiment steps
Chapter 5 Results and Discussion
Chapter 6 Conclusions
References
The author brief introduction


Figure Captions
Figure 1.1 Classification of solar cells.
Figure 1.2 The development of solar cell efficiency.
Figure 2.1 Energy spectrum of sunshine in the atmosphere (AM-0) and on surface of the earth (AM-1.5)
Figure 2.2 Energy band diagrams of solar cell.
Figure 2.3 The equivalent circuit of solar cell.
Figure 2.4 The I-V characteristic of a solar cell.
Figure 2.5 Collection probability for a representative solar cell and ,shown by the dashed lines, the carrier generation profiles for three different wavelengths of light.
Figure 2.6 Corresponding quantum collection efficiency, ηQ, as a function of wavelength.
Figure 2.7 Corresponding to spectral sensitivity (A/W), also as a function of wavelength.
Figure 2.8 Spectral response of top and middle subcells of the multi junction solar cell at 24, 45 and 75℃.
Figure 3.1 Schematic of the current-voltage characteristic
measurement system: solar simulator.
Figure 3.2 Schematic of Fresnel lens
Figure 5.1 Schematic illustration of InGaP/InGaAs/Ge triple-junction solar cell.
Figure 5.2 The quantum efficiency of A1 under the illumination condition:AM1.5.
Figure 5.3 Incident light spectrum with modulated
short wavelength intensity.
Figure 5.4 Incident light spectrum with modulated
long wavelength intensity.
Figure 5.5 Variation of subcell current and short-circuit current of sample A1 as a function of Xe lamp intensity.
Figure 5.6 Variation of subcell current and short-circuit current of sample A1 as a function of Ha lamp intensity.
Figure 5.7 The power to voltage of Xe lamp intensity being adjusted.
Figure 5.8 The power to voltage of Ha lamp intensity being adjusted.
Figure 5.9 Normalized I-V curves of Xe lamp intensity being adjusted.
Figure 5.10 Normalized I-V curves of Ha lamp intensity being adjusted.
Figure 5.11 Isc and Voc of sample A1 as a function of Xe (Ha) lamp intensity.
Figure 5.12 Efficiency of sample A1 as a function of Xe (Ha) lamp intensity.
Figure 5.13 The actual spectra measured at different times.
Figure 5.14 Comparative outdoor measured spectra and indoor modulated short wavelength spectra shown in Fig. 5.3.
Figure 5.15 Comparative outdoor measured spectra and indoor modulated long wavelength spectra shown in Fig. 5.4.




List of Tables
Table 2.1 The standard of air mass versus power per unit area is determined by NASA.
Table 4.1 The summary of recent triple junction champion efficiencies.
Table 5.1 Theory calculated current of each subcells and the measured current data by modulated Xe lamp intensity.
Table 5.2 Theory calculated current of each subcells and the measured current data by modulated Ha lamp intensity.
Table 5.3 The experiment data of electrical parameters by modulated Xe lamp intensity..
Table 5.4 The experiment data of electrical parameters by modulated Ha lamp intensity.
Table 5.5 The outdoor theory calculated current of each subcells and outdoor measured current.
Table 5.6 The outdoor measured data of solar electrical parameters and DNI at 10:51 on August 27.
Table 5.7 The outdoor measured data of solar electrical parameters and DNI at 11:17 on September 13.
Table 5.8 The outdoor measured data of solar electrical parameters and DNI at 15:28 on September 16.

References
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